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NY110 Insecticidal control of cane weevil in palms Keith Halfpapp, et al QLD Department of Primary Industries

NY110 This report is published by the Horticultural Research and Development Corporation to pass on information concerning horticultural research and development undertaken for the nursery industry. The research contained in this report was funded by the Horticultural Research and Development Corporation with the financial support of the nursery industry. All expressions of opinion are not to be regarded as expressing the opinion of the Horticultural Research and Development Corporation or any authority of the Australian Government. The Corporation and the Australian Government accept no responsibility for any of the opinions or the accuracy of the information contained in this report and readers should rely upon their own enquiries in making decisions concerning their own interests. Cover price: $20.00 HRDC ISBN 1 86423 680 9 Published and distributed by: Horticultural Research & Development Corporation Level 6 7 Merriwa Street Gordon NSW 2072 Telephone: (02) 9418 2200 Fax: (02) 9418 1352 E-Mail: [email protected] © Copyright 1997

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HORTICULTURAL RESEARCH & DEVELOPMENT CORPORATION Partnership in horticulture

Index Contents

1. INDUSTRY SUMMARY 2. INTRODUCTION 3. MATERIALS AND METHODS 3.1 Beetle culture 3.2 Study sites 3.2.1 Insecticide Screening - Bio-assay. 3.2.2 Insecticide Screening - Glasshouse Trials 3.2.3 Insecticide Residual Efficacy - Glasshouse 3.3.4 Insecticide Macro Trunk Injection - Field. 3.3.5 Mauget Micro-Trunk Injection of Insecticide - Glasshouse. 3.3.6 Modified Tree Wound Dressing to Inhibit Oviposition 4. RESULTS 4.1 Insecticide Screening - Bio-assay. 4.1.1 Insecticide Screening - Glasshouse Trials 4.1.2 Insecticide Residual Efficacy - Glasshouse. 4.1.3 Insecticide Macro Trunk Injection - Field. 4.1.4 Mauget Micro-Trunk Injection of Insecticide - Glasshouse. 4.1.5 Modified Tree Wound Dressing to Inhibit R. obscurus Oviposition. 5. SURVEY 6. DISCUSSION 7. TECHNICAL SUMMARY 8. BIBLIOGRAPHY 9. PHOTOGRAPHS 1 2 7 7 7 7 8 8 9 9 10 11 11 12 13 14 15 15 16 21 23 25 27

1

1. INDUSTRY SUMMARY

The first inquiry received indicating that sugarcane weevil borer was a pest of palms was an attack on coconut palms in Cairns in 1977. The number of reports of damage from this insect have increased since that time. Sugarcane weevil bore attacks potted and landscaping sized native and exotic palms. Infested palms are unsuitable for sale and in severe infestations the palms may die. This insect poses a serious threat to the palm industry, estimated to be worth $3.8 million in north Queensland in 1988 (Sing, pers. comm.). -A project to research control methods for this insect was initiated in response to a request from the north Queensland branch of the QNI A. A range of insecticides and application methods were trailed against sugarcane weevil borer in palm trees in north Queensland under glasshouse and field conditions. Non-insecticidal control measures including hygiene and painting the palm trunks with a water based acrylic paint were also evaluated. Field studies of the biology/ecology of the sugarcane weevil borer were undertaken. A survey of the coastal area from Cooktown to the Gold Coast in March 1993 confirmed the presence of sugarcane weevil borer and palm weevil in this area. An insecticide screening technique developed for testing chemicals against a related pest, the banana weevil borer, was used to evaluate chemicals for field trialing. Three emulsifiable concentrate formulations and four systemic granular insecticides were selected for field trials set up at two locations in the Edmonton/Wright's Creek area. No conclusive results were obtained from these trials as the level of infestation by the weevil was virtually nil. Five systemic granular insecticides and three EC formulations were used in glasshouse trials. Chlorpyrifos (Lorsban), prothiophos (Tokuthion) and bifenthrin (Talstar) were the most effective insecticides. A glasshouse trial to evaluate the residual efficacy of the successful insecticides was also carried out. Both chlorpyrifos and prothiophos were active for eight weeks, killing adult beetles placed on treated plants. Direct trunk injection was tested to reduce disruption to insect predators and reduce environmental and user hazard. Of the insecticides tested, Folimat gave the best control of larvae. However, the technique cannot be recommended because of the introduction of rots at the injection site. (Fig. 17). Subsequent to this study the following recommendations can be made to aid in the control of sugarcane weevil borer in palms: 1. Spray seedlings and small plants ( t o one metre) with 5 mL/L (larger plants with 10 mL/L) of product containing 500 g/L chlorpyrifos. Spray to the point of run-off and ensure that the insecticide finds its way behind leaf bases. Also spray the ground around the base of the palm. Two spray applications one month apart should be made during the period March-April, July-August and December-January to coincide with peak weevil activity. Do not use bagasse in a potting medium or as a mulch around the base of potted or inground trees, as female beetles are attracted to this material. As adult beetles shelter behind leaf bases during daylight remove and destroy old and dead fronds. Do not sell infested plants and destroy any heavily infested ones. All plants leaving a nursery should be checked for obvious signs of infestation.

2. 3. 4.

2 2. I N T R O D U C T I O N In recent years the cultivation of ornamental palms has increased markedly in Queensland and in 1988 the estimated value was $3.8 million (Sing, pers. comm.). Several insects proved to be important pests, particularly the sugarcane weevil borer Rhabdoscelus obscurus (Boisduval). The larvae of this weevil feed on a number of palm species making the plants unsaleable. Death or lodging of older plants may also result. Numerous reports of severe damage to palms have been received from tourist resorts at Port Douglas, the Whitsunday Islands and the Gold Coast. As most of the palms used in landscaping at these locations came from north Queensland, twenty-two growers and their nurseries were surveyed for the presence of sugarcane weevil borer. This survey was carried out in late 1989 (Halfpapp & Storey, 1991). Due to the unrestricted movement of infested palms, sugarcane weevil borer has been recorded in palms as far south as Newcastle. As well as the damage incurred in landscaping areas it is estimated that sugarcane weevil borer causes annual losses to the nursery industry in the order of $200,000, with a further $65,000 added to the cost of production due to chemical costs and their application. In response to a letter from the Cairns branch of QNIA asking for help in controlling this insect a successful application for funding was obtained and research initiated in 1991. The second part of project NY110 is to determine the pest status and distribution of palm weevil borer Diocalandra frumenti (Fabricius) in coastal Queensland was undertaken in response to a request from nurseryman in central Queensland. The recent death of mature specimens of the Canary Island Date Palm, Phoenix canariensis, in the Rockhampton area in 1991 prompted this survey (figures 18 & 19). Reports were also received of D. frumenti damage occurring to coconut palms on the Whitsunday Islands. The survey was subsequently broadened to include observations on the distribution of R. obscurus. The precise pest status of D. frumenti is open to dispute. Hill (1983) stated that "some entomologists believe that the damage is primary and results in appreciable crop losses, but others maintain that this damage is purely secondary". In December 1991 this species was found to be the primary cause of death of century old P. canariensis in the Rockhampton Botanical Gardens and the Rockhampton Grammar School (R.J. Elder 1991, pers. comm.). It had also been recorded damaging coconut palms on Hamilton Island and a number of palm species on the Southbank development in Brisbane (R. Parker 1993, pers. comm.). Although its presence had been recorded in north Queensland 1939 (Brooks, 1969) this insect had not been previously associated with primary damage to palms. In north Queensland it had been collected by K. Halfpapp on a number of occasions where it was causing secondary damage to palms following infestation by R. obscurus The following information on distribution, life history, local & overseas hosts and natural enemies of R. obscurus is an extract from a report published by Halfpapp and Storey (1991). Distribution ofR. obscurus Zimmerman (1968) believed that the sugarcane weevil borer was probably native to Papua and has since spread, its distribution ranging from the Celebes through New Guinea, south and east to Queensland, Polynesia and Micronesia and north to Hawaii. Its spread is almost certainly due to the transport of sugarcane by man.

3 Mungomery (1953) was of the opinion that sugarcane weevil borer entered Queensland in infested cane directly from New Guinea about 1896. Jarvis (1927) stated that it was first noticed in the Mossman and Johnstone Rivers sugarcane areas in 1907, spreading rapidly between mill areas as far south as Mackay through the unrestricted movement of seedcane. By the mid 1930's sugarcane weevil borer was second only to cane beetle (Scarabeidaei: Lepidiota and other genera) as a pest of sugarcane in Queensland. Mungomery (1953) believed that R. obscurus only reached a negligible status in the sugar industry when preharvest burning of the crop became almost universal. This practice destroyed most emerging adults and milling killed most larvae and pupae. R. obscurus was first recorded as a pest of palms in northern Queensland after an attack on coconut palms in Cairns in 1977. Since that time reports of damage by this insect to palms has increased markedly. This increase in activity coincides with the trend back to green harvest of sugarcane. Life History of R. obscuras Most literature on the life history of if. obscurus relates to sugarcane, especially from Hawaii where the weevil is still a major pest. The following information is largely from Nampompeth et al. (1972). The adult female chews a cavity about 3 mm deep in the sugarcane stalk, usually in adult feeding scars or cracks, sometimes at internodes or in leaf sheaths. A single egg is then laid, which hatches in 3-7 days (mean 4.6). The developing larva feeds on the pith (not the fibres), tunnelling up and down the stalk, occasionally breaking through to the surface leaving characteristic windows. The larval stage, which has about 6 instars, lasts from 45-61 days (mean 54.3). It then enters a prepupal stage of about 7 days, finally pupating in a cocoon made of a spirally woven mass of fibres and frass. After 17-25 days (mean 21) the adults emerge. Adult beetles are variable in colour, with about 6 distinct patterns of light and dark markings. Each adult weevil is 10.0 + 3.0 mm in length and 3.5 ±1.1 mm in width, while weight varies from 21.3 - 118.2 mg (mean 66.1 in males, 67.8 in females). Adults are long lived, surviving up to 70 months in captivity, but probably less in the wild. Beetles fly infrequently and are most active around dawn and especially dusk. Van Zwaluwenburg and Rosa (1940) found that R. obscurus can move considerable distances (mainly by flight), marked and released specimens being taken up to 0.5 km from release sites. They concluded that wind was probably the main environmental influence on field movement and that most infestations in new fields came from adjacent fields, rather than carrying over from crop to crop. One female can lay up to 176 eggs, 90% of which are laid in the first 25 weeks (laboratory conditions). Eggs are not laid continuously but in short periods of activity. Dharmajaju et al. (1979) discussed the weevil's life history in coconut palms. Eggs are laid in the epidermis of 4-6 years old trees. Up to several hundred larvae were found developing within the trunk of a single tree. Pink sap which exudes from wounds attracts other adults. Cocoons are found inside the trunk, the weevils leaving exit holes as they emerge. Heavy infestations weaken the trunk and the tree may fall over and die. Damage mostly occurs up to 1 metre above the ground. Overseas Hosts of/?, obscurus R. obscurus is considered to be primarily a pest of sugarcane, although Muir and Swezey (1916) believed that the original hosts were likely to have been palms and bananas.

4 Table 1. Hosts of R. obscurus reported from overseas. Host Zea mays Carica papaya Ravenala madagascariensis Strelitzia reginae Archontophoenix alexandrae Areca catechu Caryota urens Cocos nucifera Metroxylon sagu Pritchardia martii Ptychosperma elegans Roystonea elata Sabal palmetto Erianthus spp. Inocarpus fagifer * 1. Nampompeth et al. (1972) *2. Zimmerman (1968) Australian Hosts The majority of available records prior to this project in Australia are for sugarcane. Mungomery (1937) stated that he knew of no authentic record of R. obscurus feeding on bananas in Queensland. He did record Archontophoenix alexandrae as a host, the cocoons being present in felled wild trees. Table 2. Host species for R. obscurus recorded in Australia (from Halfpapp and Storey, 1991). Species Coryphoidaee Licuala spp. Phoenix canariensis Hort. Ex Chabaud Calamoideae Metroxylon salomonense (Warb.) Becc. Pigafetta filaris (Giseke) Becc. Ceroxyloideae Hyophorbe lagenicaulis (L.H. Bailey) H.E. Moore Arecoideae Caryota mitis Lour. Chrysalidocarpus madagascariensis Becc. Chrysalidocarpus lutescens H.A. Wendl. Neodypsis decaryi H. Jumelle Phloga nodifera Noronha ex. Salomon Dypsis sp. Common name Licuala Palms Canary Island Date Palm * Source

2 2

Solomon Sago Palm Pigafetta Palm

Bottle Palm

Clustered Fishtail Palm Green Cane Palm Golden Cane Palm Triangle Palm Dypsis Palms

5 Euterpe spp. Assari Palms Roystonea regia (Kunth) O.F. Cook Cuban Royal Palm Archontophoenix alexandrae (F.v. Mueller) Alexandra Palm H.A. Wendl. & Drude Bangalow Palm Archonophoenix cunninghamiana (H.A. Wendl.) H.A. Wendl. & Drude Carpentaria Palm Carpentaria acuminata (H.A. Wendl. & Drude) Becc. Normanbya normanbyi (W. Hill) L.H. Bailey , Black Palm Wodyetia bifurcata A.K. Irvine Foxtail Palm Solitaire Palm Ptychosperma elegans (R.Br.) Blume Areca catechu Ln. Betel-nut Palm Princess Palm Dictyosperma album (Bory) H.A. Wendl & Drude ex Scheff. Coconut Palm Cocos nucifera L. Queen Palm Syagrus romanzoffiana (Chamisso) Glassman Aiphanes caryotifolia (Kunth) H.A. Wendl. Coyure Palm Bactris gasipaes Kunth Peach Palm Palm classification after Uhl and Dransfield (1987). Natural Enemies A tachinid parasite of R. obscurus, Lixophaga sphenophori (Villeneuve), was successfully introduced from Papua New Guinea by Jarvis, working with the Hawaiians Muir and Kershaw, in 1910 (Mungomery, 1953). By 1918 it was well established in the Mossman area and was then reared in numbers at the Meringa laboratories of the Bureau of Sugar Experiment Stations and widely released between Proserpine and Cairns. Mungomery (1953) stated that parasitism, rates rarely exceeded 5% which he attributed to the removal of available hosts by the yearly harvest. Wilson (1960) however, noted that L. sphenophori did exercise a high degree of control of R. obscurus where conditions were favourable, such as the Tully and Mossman mill areas. In addition to L. sphenophori, Muir & Swezey (1916)) listed the following as natural enemies of R. obscurus (except where indicated). Plaesius javanus Erichson (Histeridae) Larvae and adults of this large beetle live inside weevil infested palms and bananas, feeding on weevil adults and larvae, especially on Cosmopolites and Sphenophorus (other weevil genera related to R. obscurus) in bananas. P. javanus was released in Cooran, southeast Queensland to control Cosmopolites sordidus (Germar), the banana weevil borer, in 1928 (Weddell 1932). One Plaesius larva can consume up to 34 weevil larvae per day, an adult averaging 8 per day. Waterhouse and Norris (1987) stated that despite several attempts to introduce this species into southeast Queensland and New South Wales from both Java and Fiji (where it had been successfully introduced), it failed to become established. Platysoma abruptum Erichson (Histeridae) This species is similar to P. javanus but smaller. Simodactylus sp. (Elateridae) Larvae feed on R. obscurus in palms, especially the pupal stage. Chrysopilus sp. (Rhagionidae) Larvae of these flies feed on beetle and other fly larvae in palms and bananas. Waterhouse and Norris (1987) noted the introduction into Australia in 1928 of Chrysopilus ferruginosus Wiedemann against C. sordidus. Like the histerid Plaesius javanus it failed to establish. Zimmerman (1968) lists the elaterid, Conoderus exul (Sharp)

6 and "various ants, mites, fungi and some other predators and parasites" as affecting R. obscurus numbers. Other agents are also recorded as parasites or predators of R. obscurus, including rats which will eat the cocoons and Bufo marinus Linnaeus, the cane toad, which commonly preys on R. obscurus adults (Wilson 1960). Wilson (1960) also reported that the green muscardine fungus Metarrhizium anisopliae attacks R. obscurus in Queensland and that the species was considered for biological control in 1923-4. He also reported the introduction of an unspecified entomogenous fungus from the Philippines in 1928. It was then cultured on media and transmitted to R. obscurus, but no further information is available on its success or otherwise. Zimmermann (1968) believed that satisfactory biocontrol of R. obscurus would be exceedingly difficult Current project undertaken Initially two replicated field trials using potted palms were set up at two locations south of Cairns in the Edmonton/Wrights creek area. For the nine month duration of the trials, light trapping, pit fall traps and multi-directional sticky traps were maintained at one site to obtain information on the insects ecology. Further trials, were conducted in a glasshouse at QDPI Mareeba. Three bio-assay trials, two insecticide screening trials and one trial to establish insecticide residual efficacy were conducted. One trial to determine the efficacy of painting palm trunks with a modified acrylic paint to prevent oviposition and trials to determine the efficacy of a micro and macro trunk injection technique for pesticide application were evaluated. A survey to determine the incidence and distribution of R. obscurus and D. frumenti in coastal Queensland was conducted in March 1993.

7

3. MATERIALS AND METHODS

3.1 Beetle culture

To ensure an adequate supply of beetles for use in laboratory and glasshouse testing, adult beetles were field collected from infested sugarcane plantations. Traps were prepared by splitting 30 cm long billets and wrapping twenty split pieces in black plastic sheeting, leaving both ends open (Anon, 1982). These parcels were then placed ten metres apart in alternate rows of cane known to be infested with the weevil. Weevils were attracted to the bait and were collected ten days later. Up to two hundred baits would be prepared and laid at any one time and would yield from 200-1,000 adult beetles. The ratio of male to female in a natural population is 2:1. The adults were brought back to the laboratory where they were maintained on pieces of split cane and housed in 30cm2 aluminium cages (figure 15). The food and water source were replaced at four day intervals and any dead insects removed. Breeding the insect in the laboratory was only partially successful. Infested pieces of cane along with healthy pieces were placed in 60 L plastic rubbish bins. The insects did reproduce, but the resulting progeny were much smaller than the original adults and considered unsuitable for use in experiments. A plot of sugar cane was planted at Walkamin Research Station to provide a food source for the cultures maintained in the laboratory. 3.2 Study sites

Experiments were undertaken at two commercial nurseries south of Cairns in the Edmonton/Wrights'creek area and in a glasshouse and laboratory at QDPI Mareeba. 3.2.1 Insecticide Screening - Bio-assay.

A technique developed for testing chemicals against the banana weevil borer was used (B. Pinese and K. Halfpapp, unpublished) to screen suitable insecticides for field testing. The following insecticides were evaluated in three glasshouse bio-assay trials at Mareeba. Trade Name Temik Furadan Rugby Disyston Thimet Counter Miral Tokuthion Lorsban Talstar Common Name aldicarb carbofuran cadusafos disulfoton phorate terbufos isazophos prothiofos chlorpyrifos bifenthrin Formulation 150G 100G 100G 50G 100G 100G 100G 500EC 500EC 100EC Rate of a.i. 4 gai/m2 4 gai/m2 4 gai/m2 4 gai/m2 4 gai/m2 4 gai/m2 4 gai/m2 2.5 gai/m2 5.0 gai/m2 0.2 gai/m2

Systemic granular insecticides with known activity against weevils were used in trials 1 and 2. Selected granular insecticides along with EC formulations were used in trial 3. Plastic trays (35 x 29 x 6 cm) were filled with a kraznozem soil and used as individual plots. Chemicals were applied to the soil surface at rates recommended for field use. Following chemical treatment plots were kept in a glasshouse where they were watered daily. All plots

8 were randomised and replicated four times. The soil was lightly watered prior to the initial treatment and if required before soil samples were collected. For each liquid formulation 200 mis of solution was applied evenly to the soil surface using a small watering can. Granular formulations were premixed with 10 grams of fine washed sand and applied with a shaker pack. A 70 x 70 x 10 mm soil sample was taken from each treated plot 4 weeks after treatment. Samples were sieved and placed in 250mL screw top plastic jars. Ten adult weevils, 5 of each sex, were placed on the soil surface which had been wetted with lOmL of water. After 24 hours a small piece of sugarcane which acted as an attractant and food was placed in the container. At 48 hours the weevils were removed and placed in a petri dish on moist filter paper and assessed for mortality. Mortality was recorded at 48 and 96 hours after the initial exposure. Weevils were placed dorsally on filter paper and were considered dead if they failed to right themselves after 30 minutes. Weevils were maintained on moist filter paper at 25° ± 1°C for the period of the test. 3.2.2 Insecticide Screening - Glasshouse Trials

Because of the extremely low levels of infestation experienced in the field trials, glasshouse screening of pesticides was undertaken. Cuban Royal palms Roystonea regia were used in all glasshouse trials. These single trunk palms are readily available and are a popular host for R. obscurus. Plants were fertilised with Osmocote® and weeds controlled by the application of Ronstar®. Irrigation was applied for one hour each morning and for ten minutes at 1300 hrs by an automatic watering system. Plants were grown in 200mm pots and were 1.75 - 2.0m tall when used in experiments. Cadusafos, terbufos and disulfoton were not included in the insecticide screening trials. Mocap lOOg (ethoprophos) at 4 gai/m2 was included. Treatments were replicated four times in two completely randomised experiments. To ensure an adequate larval population, six adult beetles (three of each sex) were caged on individual plants. Cages were constructed from a synthetic mosquito net and fitted around the top of pots and secured by a drawstring around the palm trunk (Fig. 14). Insecticide treatments were applied 6-8 weeks after caging of adults to allow time for an adequate larval population to develop. Cracking of the trunk and the appearance of a jelly-like exudate (Fig. 9) were signs used to indicate the presence of a population (Halfpapp and Storey, 1991). EC formulations were applied with a 15L knapsack sprayer and the granular formulations mixed with fine clean sand and applied with a shaker pack. Plants were sprayed to the point of run-off. The soil surface was also sprayed. Plants were removed from the glasshouse before the application of EC formulations and allowed to dry before being replaced. Four weeks after application plants were destructively sampled and the number of living and dead larvae recorded. 3.2.3 Insecticide Residual Efficacy - Glasshouse

Although chlorpyrifos was selected as the chemical most suitable for registration, bifenthrin and prothiophos were included in a glasshouse trial to evaluate their residual properties. This information will be of use in the future should resistance to chlorpyrifos develop.

9 Chlorpyrifos (5.0 gai/L and 2.5 gai/L), bifenthrin (0.1 gai/L and 0.2 gai/L) and prothiofos (2.5 gai/L and 1.25 gai/L) were evaluated for residual efficacy. All chemicals were applied at 8, 4 and 2 weeks before adult weevils were placed on the palms. Six adult weevils were caged on each plant and the number of living and dead individuals recorded two weeks later. Treatments were replicated four times in a completely randomised experiment. 3.3.4 Insecticide Macro Trunk Injection - Field.

Trunk injection of trees with systemic chemicals to control a number of insect pests has been an accepted practice for a number of years. The use of this technique is highly desirable as a means of insect control as toxic chemicals do not enter the environment and are wholly contained within the tree. This method of insecticide use has application where trees are either too high for conventional spray technology or treatment would cause unacceptable levels of pollution. A number of insecticide injection treatments are currently recommended by the Queensland Department of Primary Industries for use on a range of pests attacking ornamental trees. In 1991 the Northern Territory Department of Primary Industries and Fisheries conducted trunk injection trials to control Parlatoria scale, Parlatoria blanchardii (Tarz) on the date palm Pheonix dactylifera and in 1992 to control Palm leaf beetle, Brontispa longissima (Gestro) on the coconut palm Cocus nucifera (S. Smith, pers. comm.). Specimens of Phoenix canariensis, estimated to be worth $10,000.00 each at a resort in the Whitsunday Islands (Resort Management, pers. comm.) were known to be infested with R. obscurus. This knowledge, plus reports from Rockhampton of D. frumentii damaging the same species prompted the testing of this technique. A 10mm hole was drilled in the base of landscaping size Royal palms and the chemical injected using a 200ml disposable syringe. After injection the holes were sealed. The following insecticides were evaluated in a field trial at Mossman. Trade Name Common Name Formulation Rate of ai/cm of trunk circumference 0.8 gai 0.35 gai 0.50 gai 0.40 gai 0.75 gai

Folimat Confidor Lorsban Nuvacron Orthene 3.3.5

omethoate imidacloprid chlorpyrifos monocrotophos acephate

800 EC 350 FL 500 EC 400 EC 750 WP

Mauget Micro-Trunk Injection of Insecticide - Glasshouse.

The Mauget micro-injection technique was trialed in a glasshouse experiment because of the problems experienced with macro injection in palms. This technique was developed in America to deliver systemic fungicides, insecticides and fertilizer directly into the sap flow of trees. The technique is non polluting and is harmless to beneficial insects or wildlife. This system for trunk injection consists of a hollow feeder tube 4 mm in diameter and 70 mm long with one end cut at a 15° angle and a sealed disposable self-pressurising plastic unit which contains the insecticide. The feeder tubes were implanted in the palm trunks after a 4 mm hole had been drilled, approximately 75 mm above the base. The plastic capsules were

10 pressurised by compressing and then placed on the tubes. As the tube enters the connecting hole an internal diaphragm is ruptured and the material is forced out of the capsule and into the tree. When the capsules were empty, the units with the feeder tubes were removed from the palms and the holes sealed. The following insecticides were evaluated in a glasshouse trial. Trade Name Nuvacron Folimat Metasystox-R Common Name monocrotophos omethoate oxydemeton-methyl Formulation 400 EC 800 EC 500 EC , Rate of ai/cm of trunk circumference 0.4 gai 0.8 gai 0.5 gai

Treatments were replicated four times in a completely randomised experiment on Cuban Royal palms which were approximately 2-2.5m high with a mean trunk diameter of 150mm. As in previous glasshouse insecticide screening trials plants were infested with cane weevil larvae and were treated one month after the adults had been placed on the plants. 3.3.6 Modified Tree Wound Dressing to Inhibit Oviposition

Following claims from a commercial operator that painting the basal area of palms with a modified acrylic tree wound dressing would prevent infestation by R. obscurus and that copper napthanate would prevent fungal infection in wounds caused by the insect a trial to substantiate these claims were undertaken. The material triaied was Australian Treecare Services tree wound dressing. The formulation is an acrylic/nylon and is water soluble. Two colours, brown and off-white were applied to twelve Cuban Royal palms 2.0-2.5 m tall. The paint was applied so as to leave half of the trunk untreated, giving the weevils a choice. Three pair of adults were introduced onto each palm and the effects observed one month later. A formulation of copper napthanate was painted onto the basal area of six palms.

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4. RESULTS

4.1 Insecticide Screening - Bio-assay.

Percentage mortality of adult weevils from the three trials is shown in Figs. 1, 2 and 3.

cadusafos

aldicarb

isazophos 48 Hours post exposure 96 Hours post exposure 20 40 60 80

control

100

% Mortality

Fig. 1. Trial 1 - Mortality of sugarcane weevil borer adults following exposure for 48 and 96 hours to treated soil at 4g ai/m2.

aldicarb 48 Hours post exposure control

-H

96 Hours post exposure 20 40 60 80

100

% Mortality

Fig 2. Trial 2 - Mortality of sugarcane weevil borer adults following exposure for 48 and 96 hours to treated soil at 4 g ai/m2.

12

bifenthrin 0.2g ai/m2 chlorpyrifos 5.0g ai/m2 prothiofos 2.5g ai/m2 terbufos 4g ai/m2 phorate 4g ai/m2 carbofuran 4g ai/m2 cadusafos 4g ai/m2 aldicarb 4g ai/m2 control 20 40 60 48 Hours post exposure 96 Hours post exposure

80

100

% Mortality

Fig. 3 -Trial 3 - Mortality of sugarcane weevil borer adults following exposure for 48 and 96 hours to treated soil. 4.1.1 Insecticide Screening - Glasshouse Trials

The mean number of living larvae per palm is presented in Figs. 4 and 5. In the first trial chlorpyrifos (2.5 gai/L) outperformed all the candidate granular pesticides. The mean number of live weevils per palm was three for chlorpyrifos, while the mean number of live larvae for the granular pesticides ranged from fourteen for carbofuran through to thirty for aldicarb.

5

10

15

20

25

30

Mean number of live weevil larvae per palm

Fig. 4. Glasshouse insecticide screening trial No. 1. Chemicals applied at the rate of 4g ai/m2 except chlorpyrifos (2.5 g ai/L) as a cover spray.

13

prothiophos 1.25g ai/L bifenthrin 0.2g ai/L ethoprophos 4g ai/m2 chlorpyrifos 5.0g ai/L chlorpyrifos 2.5g ai/L terbufos 4g ai/m2 phorate 4g ai/m2 carbofuran 4g ai/m2 aldicarb 4g ai/m2 Control

I I I I I i i

0

2

4

6

8

10

12

14

16

18

20

Mean number of live weevil larvae per palm

Fig. 5. Glasshouse insecticide screening trial No. 2. 4.1.2. Insecticide Residual Efficacy - Glasshouse. The percentage mortality post treatment is presented in Fig. 6.

Control

chlorpyrifos 5.0g ai/L

chlorpyrifos 2.5g ai/L Aged 2 weeks bifenthrin 0.1g ai/L Aged 4 weeks Aged 8 weeks bifenthrin 0.2g ai/L

prothiophos 2.5g ai/L

prothiophos 1.25g ai/L

10

20

30

40

50

60

70

80

90

100

% Mortality post treatment

Fig. 6. Glasshouse insecticide ageing trial.

14 4.1.3. Insecticide Macro Trunk Injection - Field. Although the larval population was considered to be low, the results obtained were worth presenting. Records of larval mortality were obtained from only the monocrotophos treatment. Percentage of mortality of adults ranged from 100% for monocrotophos to 52% for chlorpyrifos. An interesting observation made from this trial w,as the high mortality (100%) inflicted by the fly parasite Lixophaga sphenophori (Villeneuve) (Fig. 12 & 13). Results from the survey carried out in 1989 (Halfpapp and Storey) recorded a parasitism level of 57% at Mirage Resort, Port Douglas. In both situations pesticides had not been used in management practices. Parasitism of R. obscurus is rarely recorded from sugarcane. (K. Chandler, pers. comm.).

monocrotophos 0.40g ai/cm acephate 0.75g ai/cm

chlorpyrifos 0.05g ai/cm imidachloprid 0.35g ai/cm omethoate 0.8g ai/cm

· Larvae · Parasitised pupae B Dead pupae ·Adults

Control

40 50 60 70 80 90 100 % Mortality Fig. 7. Mortality of sugarcane weevil borer following trunk injection of insecticides to Cuban Royal Palms.

0

10

20

30

15 4.1.4 Mauget Micro-Trunk Injection of Insecticide - Glasshouse.

The percentage mortality is presented in Fig. 8.

% Mortality monocrotophos 0.4g ai/cm omethoate 0.8g ai/cm oxydemeton-methyl 0.5g ai/cm Control

--I h-

10

20

+

30 40 50 60 70 80 90 100 % Mortality

Fig 8. Mortality of sugarcane weevil borer larvae following Mauget microjet trunk injection. 4.1.5. Modified Tree Wound Dressing to Inhibit R. obscurus Oviposition. The palms treated with Australian Tree Care Services wound dressing were inspected after one month. There were no differences at all between treated and untreated sections of the palm, weevils laying eggs into both sections (Fig. 16). The plants treated with copper napthanate exhibited phytotoxic symptoms. The material produced irregular burn type lesions on the epidermis. Although plants did not appear to suffer in other ways it would not be advisable to use this preparation, particularly on younger trees.

16

5. SURVEY

A survey to determine the incidence and distribution of Rhabdoscelus obscurus (Boisduval) and Diocalandra frumenti (Fabricius) in coastal Queensland was conducted in response to a request from central Queensland nurserymen following reports of damage and the death of palms from attack by D. frumenti (Fig. 19). Investigations were undertaken by K.H. Halfpapp (DPI Mareeba), R.J. Elder (DPI Rockhampton) and R. Parker (DPI Indooroopilly). Survey work commenced in March 1993 and was undertaken in three areas: 1. Cooktown to Bowen (K.H. Halfpapp). 2. Dingo Beach (south of Bowen) to Gladstone (K.H. Halfpapp & R.J. Elder). 3. Bundaberg to the Gold Coast (R. Parker). Palms growing in foreshore areas, botanic gardens, resorts and parks as well as nursery stock were inspected for the presence of D. frumenti and R. obscurus. Twenty-six palm nurseries in the Cooktown/Bowen area, seven in the Dingo Beach/Gladstone area and twenty-two in the Bundagerg/Gold Coast areas were sampled. Palm weevil borer Damage The larvae attack all parts of the palm, especially roots, leaves and fruit stalks, and cause premature fruit-fall. The leaf bases are bored from the trunk out to the leaflets. In some areas the trunk is also bored, at all heights (Hill, 1983). In some infested specimens of Phoenix canariensis observed in the Rockhampton area after all fronds had been attacked (Fig. 18 & 19) the crown of the plant was infested. It is at this stage the death of mature specimens of P. canariensis was recorded. In the Cooktown/Cape Tribulation area D. frumenti was recorded from the Miniature Date Palm (Phoenix roebelenii), Alexandra Palm (Archontophoenix alexandrae) and Coconut (Cocus nucifera). At Townsville and Magnetic Island damage was observed on Golden Cane (Chryalidocarpus lutescens), Canary Island Date Palm (P. canariensis), Green Cane (Chrysalidocarpus lucebensis) and C. nucifera. In central Queensland observations were made of damage on similar hosts as north Queensland. Records from south eastern Queensland include The Kentia Palm (Howea belmoreana) as well as species recorded from other areas. In all areas surveyed both new and old damage i.e. emergence holes on new and old fronds and leaf bases was clearly evident. Apart from the central Queensland area (Whitsunday Coast and Rockhampton) the damage sustained by palms was not considered to be excessive or detrimental.

17 However, in the Rockhampton area damage to P. canariensis in particular was extremely severe. It was from this location that the death of very old specimens of P. canariensis was recorded. In the city of Rockhampton twenty-three P. canariensis in public parks were recorded as being severely affected by D. frumenti (Figs. 18 & 19). Another fifteen P. canariensis were severely affected at Emu Park. On a number of islands in the Whitsunday group and Great Keppel Island moderate damage was recorded mainly in C. nucifera. Parasitism of D. frumenti by the wasp Scleroderma spp. (family Bethylidae) was recorded from all areas surveyed. The level of parasitism recorded was not significant. Distribution of D. frumenti in coastal Queensland is recorded on the distribution map (Fig. 20). Sugarcane weevil borer Damage In younger palms R. obscurus larvae mine the central portion of the stem completely destroying the plant. In older palms larvae mine the thicker leaf bases as well as extending for a short distance into the trunk. Emergence holes and splitting of the trunk causes difigurement in older palms making them unsuitable for sale. Obvious symptoms of R. obscurus infestation is a jelly-like exudate from holes in leaf bases (Fig. 9) and splitting of the trunk at or near the base. Staining of the trunk occurs, especially if the palm sustains a high population of larvae (Halfpapp and Storey, 1991). R. obscurus was found infesting palms from Cooktown to the Gold Coast. As well as the palm species listed in Table 2 it was recorded from specimens of P. canariensis at a resort in the Whitsunday Islands. It was recorded from nurseries (in ground and potted plants), in landscaping areas (private and public) and at two locations in stands of native palms in the Mackay area. At Cape Hillsborough National Park R. obscurus was responsible for considerable damage inflicted on a stand of Phytosperma elegans. In this instance the crown of infested specimens had fallen. Larvae and adults were recovered from these palms. In the Reliance Creek National Park large numbers of the insect were recovered from young Alexander palms and from under the leaf sheaths of older specimens. The only other recent record of R. obscurus being collected from the wild is that supplied as a personal communication from A. WalfordHuggins, i.e. Grey Peaks (near Yarrabah) in 1977 ex: A. alexandrae. R. obscurus was the major pest in the twenty-two nurseries and palm wholesalers surveyed in the area Bundaberg to the Gold Coast. It was also a major problem at a number of resorts and locations in this area. At this stage many nurseries had ceased sourcing palms from north Queensland. In all areas except for Cape Hillsborough and Reliance Creek, evidence of the introduced parasite Lixophaga sphenophori (Villeneuve) was observed. Infestation levels varied from a very low 1% up to 35% parasatism. The distribution of R. obscurus in areas where sugar cane is not grown can be attributed directly to the sale and transport of affected plants. It can be assumed that the parasite was transported in plants infested with the host. In areas where sugar cane is grown, particularly

18 north Queensland, evidence suggests that the adult weevil seeks out palms when its primary host is harvested. Other information obtained from this survey indicates that a number of other insects do or have the potential to cause problems in palm culture in coastal Queensland. On the Capricorn Coast, Coconut white fly (Aleurodicus destructor) Mackie, although considered to be at a low level at the time of the survey was quite common in the previous year (pers. comm. R.J. Elder). Numerous scale insects (many unidentified) including pink wax (Ceroplastes rubens) Maskell and green coffee scale {Coccus viridis) (Green) were recorded. A large black unidentified scale recorded on Pheonix spp. and Pritchardia pacifica was killing younger palms in a nursery at the Gladstone Botanical Gardens. Mealybugs Pseudococcus spp. are common pests on palms in nurseries and landscaping areas in coastal Queensland. At a number of locations proven biological control methods i.e. use of predator beetles (Cryptoleamus montrouzieri Musant) or parasitic wasps (Leptomastix dactylopii Howard), were recommended for use.

19

DISTRIBUTION OF Diocalandra frumenti (Fabricius) (Palm Weevil Borer) IN COASTAL QUEENSLAND

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COOKTOWN J C O O K T O W N BLO0MFIELD4I_ T D CAPE TRIBULATION MOSSMANS, P0RTD0U6LAS ^ Q N O R T H E R N BEACHES HAMBLEO0Ni|afflS MBRAMSTON BEACH INWSFAU 4;INNISFAIL MISSION BEACHO INGHAM LmfcoRREST BEACH

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Figure 20. Distribution of D. frumenti in coastal Queensland.

20

DISTRIBUTION OF Rhabdoscelus obscurus (Boisduval) (Sugarcane Weevil Borer) IN COASTAL QUEENSLAND

; LEGEND o Sugarcane Weevil Borer Location * Major Towns Coastline

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Fig. 21. Distribution of/?, obscurus in coastal Queensland.

21

6. DISCUSSION

In the 1989 survey of growers located in the area from Cape Tribulation to Bramston Beach all but five of the twenty-two participants had problems with R. obscurus, ranging from mild to severe. The five negative cases included some recently established plots or growers using regular heavy chemical applications (Halfpapp & Storey, 1991). Table 2 in this report lists the current known palm hosts in Australia. To this list can be added Phoenix canariensis, recorded as a host at Hayman Island in 1993. Halfpapp and Storey, (1991) lists Carpentaria acuminata, Chrysalidocarpus lutescens, Roystonea regea and Wodyetia bifurcata as the most susceptible palm hosts. However, one long term grower is of the opinion that there are few palms that R. obscurus would not attack. Mungomery (1953) believed that R. obscurus reached its current negligible pest status in the sugar industry when pre-harvest burning of the crop became almost universal. Since the return to green harvest and the practice of trash blanketing (covering the crown of harvested cane stools with leaf material), the incidence of this pest both in the sugar and nursery industry has been increasing. Palm nurseries located in close proximity to sugarcane growing areas need not be targeted by R. obscurus. This is evident in the failure of two trials located on nurseries south of Cairns. The distribution of this insect in sugarcane fields is not homogenous and is influenced by a number factors e.g particular soil types and areas subject to seasonal water-logging are prone to infestation by the insect. Also management practices such as the use of resistant varieties can have a significant effect on the population. As mentioned previously in this report the spread of R. obscurus to non sugarcane growing areas can be attributed to the sale of infested plants. The current survey has established that R. obscurus in now present from Cooktown to the Gold Coast (Fig. 20) and reports have been received of it being established in palms as far south as Newcastle. The main aim of this study was to provide a control strategy for R. obscurus for the nursery industry. After a series of insecticide screening trials chlorpyrifos was selected as the most likely candidate for control of weevils in palms. Together with information obtained on the insects' behaviour observed in the field the following schedule was formulated: Insecticidal 1. Spray seedlings and small plants (to one metre) with 5 mL/L (larger plants with 10 mL/L) of product containing 500 g/L chlorpyrifos. Spray to the point of run-off and ensure that the insecticide finds its way behind leaf bases. Also spray the ground around the base of the palm. Two spray applications one month apart should be made during the period MarchApril, July-August and December-January to coincide with peak weevil activity.

2.

Cultural 1. Do not use bagasse in a potting medium or as a mulch around the base of potted or inground trees, as female beetles are attracted to this material.

22 2. As adult beetles shelter behind leaf bases during daylight remove and destroy old and dead fronds. Do not sell infested plants and destroy any heavily infested ones. All plants leaving a nursery should be checked for obvious signs of infestation.

3.

Despite these means of controlling weevils in palms, injection techniques offered the potential to limit the environmental impact of chemical use. However, experiments showed that although these techniques are a very efficient and an ecologically acceptable way of treating trees they cannot be recommended for treatment of palms. When the palms were destructively sampled one month after treatment it was noted that all of the insecticide treatments had initiated rots within the trunk (Fig. 17). This similar damage was observed at one of the Whitsunday Island resorts where ground staff had previously experimented with trunk injection on coconuts. Twelve months after the experiment the trunk section around the injection site became slightly depressed and when cut down and sectioned longitudinally, rots and discolouration of tissue were observed. Because of the detrimental physical effect on the plant, this treatment can only be recommended under exceptional circumstances. At the time of the trial micro trunk injection could not be trialed on larger palms. Perhaps this technique could be investigated in future work. Conclusion Control of sugarcane weevil borer in the nursery industry should be obtained if the recommendations, both cultural and insecticidal, outlined in this report are followed. However, the authors foresee that this insect will continue to be a serious pest of palms and will grow in importance in areas where a control programme cannot be implemented, e.g. in public and private landscaping, with particular reference to resort areas where chemical control is precluded or severely limited. The severe and sometimes fatal damage inflicted by palm weevil borer to Phoenix spp .in central Queensland and the extent of damage to palms on resort islands in the Whitsundays group will continue to be a problem. As with R. obscurus, D. frumenti will grow in importance as a pest of exotic palms. Currently there are no registered pesticide treatments for control of palm weevil borer. It is known that trunk injection of monocrotophos will give satisfactory control. However, the detrimental effects of trunk injection on palms must be taken into account when considering this form of treatment. Observations made by the author suggest that chlorpyrifos sprays at the rates recommended for sugarcane weevil borer, plus the painting of cut surfaces with a commercial acrylic paint following pruning to deter infestation will contribute towards control. Recommendations Further research of sugarcane weevil borer and palm weevil borer biology on palms should be undertaken so that control methods can be optimised. Control methods for both insects should be further investigated. Insecticide trunk and frond injection, particularly micro-injection techniques, should be examined to minimize the damage caused to internal tissue.

23

7. TECHNICAL SUMMARY

A number of EC Formulations and systemic granular insecticides were trialed against sugarcane weevil borer, Rhabdoscelus obscurus (Boisduval), in palm trees under field and glasshouse conditions in north Queensland. Non-insecticidal controls, including hygiene and painting of palm trunks with a water based acrylic paint, were also evaluated. A survey of the area from Cooktown to the Gold Coast was undertaken in March 1993 to determine the geographic distribution of R. obscurus and palm weevil borer, Diocalandra frumenti (Fabricius), in coastal Queensland. Insecticides used in field and glasshouse trials were initially screened in bio-assay trials using a technique developed for screening insecticides against the banana weevil borer, Cosmopolities sordidus Germar, (Pinese and Halfpapp, 1991, unpublished data). Three EC formulations and four systemic granular chemicals were included in two field trials run concurrently for nine months in the Edmonton/Wrights Creek area. Records of damage and the presence of R. obscurus adults and larvae were so low that future field work was considered to be on no value. During the nine months that the field trials were conducted, pit fall traps, multi-directional sticky traps and a mercury vapour light trap were maintained to obtain information on the insects' ecology. (Figs. 10 & 11). Results from the study were fruitless as nil to extremely low numbers of adults were recorded. Due to the poor performance of the field trials it was decided to conduct further trial work under controlled conditions. Field collected R. obscurus adults were used in glasshouse screening trials to determine the efficacy of a range of selected insecticides. Five granular insecticides and three EC formulations were screened in three trials. Plants were infested with R. obscurus six weeks prior to treatment. The EC formulations chlorpyrifos, bifenthrin and prothiophos were the most effective insecticides. Control exerted by the granular formulations was not as effective. In a glasshouse trial to determine residual properties, bifenthrin (0.2g a.i./L, O.lg a.i./L), chlorpyrifos (5g a.i./L, 2.5g a.i./L) and prothiophos (2.5g a.i./L, 1.25g a.i./L) were applied as cover sprays. Chlorpyrifos and prothiophos at both rates were active for eight weeks, killing adult weevils placed on treated plants. One of the prime objectives of this project was to provide in the short term an effective chemical control for R. obscurus. Chlorpyrifos was recommended for use since it had current registration in the nursery industry. To reduce environmental pollution and reduce the hazard to operators, macro and microjet trunk injection techniques were trialed. Both techniques required holes to be drilled in the palm trunk to introduce chemical under pressure. The techniques resulted in high larval mortality but could not be recommended because rots developed at the injection site. Water soluble acrylic/nylon tree dressing applied to the trunk did not prevent oviposition and no differences between painted and unpainted plants were observed. (Fig. 16). Results from the survey indicated that R. obscurus and D. frumenti were present from Cooktown to the Gold Coast. Parasitism of both species was noted in the area surveyed. R.

24 obscurus is parasitised by the introduced tachinid fly Lixophaga sphenophori (Villeneuve) while D. frumenti is parasitised by the wasp parasite Scleroderma sp. (family Bethylidae). The following recommendations have been formulated as a result of this study and are contained in the QDPI publication "Managing insects and mites in horticultural crops" edited by E. Brough, R. Elder and C. Beavis (1994). Insecticidal 1. Spray seedlings and small plants (to one metre) with 5 mL/L (larger plants with 10 mL/L) of product containing 500 g/L chlorpyrifos. Spray to the point of run-off and ensure that the insecticide finds its way behind leaf bases. Also spray the ground around the base of the palm. 2. Two spray applications one month apart should be made during the period March-April, July-August and December-January to coincide with peak weevil activity. Cultural 1. Do not use bagasse in a potting medium or as a mulch around the base of potted or inground trees, as female beetles are attracted to this material. 2. As adult beetles shelter behind leaf bases during daylight remove and destroy old and dead fronds. 3. Do not sell infested plants and destroy any heavily infested ones. All plants leaving a nursery should be checked for obvious signs of infestation.

25

8. BIBLIOGRAPHY

Anon., 1982. Ann. Rep. Fiji Sugar Res. Centre. 110-112. Brooks, J.G., 1969. Records of Coleoptera from Australia. J. Aust. ent. Soc, 1969. 8: 211, 212. Dharmaraju, E., Berger, A., Ulupago, M. and Aupaaii, E. L979. The sugar cane weevil on coconuts. Alafua Agric. Bull. 4; 8-9. Halfpapp, K.H. and Storey, R.I. 1991. Cane weevil borer, Rhabdoscelus obscurus (Coleopetera:Curculionidae), a Pest of Palms in Northern Queensland, Australia. Principes 35(4): 199-207. Hill, D.S. 1983. Agricultural insects pests of the tropics and their control. Cambridge University Press. 746 pp. Jarvis, E. 1927. Notes on insects damaging sugar cane in Queensland Exper. St. Division of Entomology. Bull. 3: 13-15. 2nd. Ed.

Old. Bur. Sugar

Lever, R.J.A.W. 1969. Pests of the coconut palm. FAQ Agricultural Studies No. 77: 1-190. Mungomery, R.W. 1937. Progress report of sugar cane beetle borer investigations in north Queensland. Proc. Old. Soc. Sugar Cane Technologists 8th annual Confer. Cairns Old: 49-62. Mungomery, R.W. 1953. The rise and fall of the sugar cane weevil borer pest in Queensland. Proc. Int. Society Sugar Cane Technologists 8th Congress Jamaica: 586593. Muir, F. & Swezey, O.H. 1916. The cane borer beetle in Hawaii and its control by natural enemies. Hawaiian Sugar Planters Assoc. Exp. Sta. (Ento. Sef). Bull. 13: 1-102. Napompeth, B., Nishida, T. and Mitchell, W.C. 1972. Biology and rearing methods of the New Guinea Sugarcane weevil, Rhabdoscelus obscurus. Hawaii Agric. Exper. Sta., College of Tropical Agric. U. of Hawaii Tech. Bull. 85: 1-51. Uhl, N.W. and Dransfield, I. 1987. Genera Palmarium. A Classification of Palms Based on the Work of Harold E. Moore, Jr. Allen Press, Lawrence, Kansas. 610 pp. Van Zwaluwenberg, R.H. and Rosa, J.S. 1940. Field movement of sugar cane beetle borer adults. Hawaiian Planters Record 44: 3-6. Waterhouse, D. and Norris, K.R. 1987. Biological Control: Pacific Prospects. Inkata Press, Melbourne. 454 pp. Wilson, F. 1960. A review of the biological control of insects and weeds in Australia and Australian New Guinea. Commonwealth Institute of Biological Control. Technical Communication No. 1: 1-102.

26 Weddell, J.A. 1932. The Banana Weevil Borer. Brief notes on Plaesius javanus Er., The Histerid Predator. Queensland Agri. Jour. 38: 24-29. Zimmerman, E.C. 1968. Rhynchophorinae of South eastern Polynesia. Pacific Insects 10 (1): 47-77.

27

9. PHOTOGRAPHS

Fig. 9. Typical external symptoms of sugarcane weevil borer damage to palms

28

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Fig. 10. Multidirectional sticky trap. Installed at field trial site to monitor movement of R. obscurus adults

29

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Fig. 11. Pitfall trap. Installed at field trial site to monitor movement of adult R. obscurus

30

Fig. 12. Adult Lixophaga sphenophori (Villeneuve). Fly parasite of R. obscurus

Vv.... - *> Jk

Fig. 13. Empty pupal cases of fly parasite next to pupal case of R. obscurus. Weevil pupal cases made from spirally - woven fibres

31

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F 1 ' 1i · ' i %i _M i * ?il 41* n\t · «

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Fig. 14. Roystonia regia palms used in glasshouse trials. Note mosquito net sleeve used to confine adult weevils to plants

Fig. 15. 30 x 30cm aluminium cages used to maintain adult weevils for trial work. Split pieces of sugarcane were used as a food source

32

m;

' *

-

*-»·',

Fig. 16. Acrylic/nylon tree wound dressing trialed as a barrier to egg laying. Note brown coloured exudate from larval activity

-

33

Fig. 17. Rots developed within one month of macro trunk injection of insecticides into Roystonia regia

34

Fig. 18. Diocalandra frumenti (Fabricus). Palm weevil borer adults 6-8mm long, shiny black with four large reddish spots on elytra. Note fras in gallery within leaf midrib

Fig. 19. Specimen tree of Phoenix canariensis infested with D. frumenti

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