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United States Department of Agriculture

Agricultural Research Service


Location: Subtropical Insects and Horticulture Research

2007 Annual Report

1a.Objectives (from AD-416)
To characterize plant responses to feeding by horticultural pests, identify sources and genetic mechanisms of plant resistance to subtropical pests, and select resistant germplasm. To develop and implement biological control programs that reduce the economic importance of subtropical pests of horticultural crops. To increase our knowledge of salient aspects of the biology and behavior of invasive horticultural pests in association with their host plants and natural enemies. Identify combinations of pest control tactics for pests of floricultural and nursery/landscape plants that interact synergistically to improve pest control, are practical to implement, and will minimize environmental disruption.

1b.Approach (from AD-416)
IPM strategies based on biological control will be developed. Natural control of subtropical insect pests by native and imported biological control agents will be assessed, and methods of conservation and augmentation to boost natural control by these agents will be investigated. Exotic biological control agents for invasive insect pests will be identified through literature reviews, collaborations with foreign scientists, or foreign exploration; adhering to federal and state regulations, these agents will be imported into the US, evaluated under federal or state quarantine facilities, released and monitored for establishment and impact. IPM strategies based on plant resistance will be developed. Insect bioassays and field trials will be conducted to identify plant varieties that are pest resistant. Citrus, vegetable and ornamental germplasm as well as non-host plant species will be screened; genes associated with insect resistance will be cloned, characterized and considered for cultivar improvement through traditional and transgenic procedures. When plant resistance is found, plant products responsible for resistance will be identified and explored for use in IPM. Transgenic plants produced at USHRL or elsewhere will be evaluated for effects on insect biology, resistance to pests, and disease transmission by insect vectors. The genetic bases of insect biology and of interactions among insect vectors, plant pathogens and host plants will be investigated using molecular techniques and genomics analyses, and IPM opportunities based on these investigations will be pursued. Molecular techniques will be used to examine the biology, gene expression and biochemical pathways of exotic insect pests. Vector-pathogen relations will be characterized biochemically and biologically, and the results will be applied to insect pest problems. Research on insect biology and behavior will be conducted to advance IPM. Biorationals such as entomopathogenic fungi, viruses and bacteria, microbials, sugar esters, oils, and azadiractin that have potential as environmentally benign IPM components will be identified and assessed. Methods of monitoring and estimating infestation densities of insect pests and their natural enemies will be developed including traps baited with attractants and sampling protocols. The ecology of insect pests and their natural enemies will be assessed in relation to pest management.

3.Progress Report

Diagnostics for the Q biotype of Bemisia tabaci. Invasion of the Q biotype into the U.S. discovered in 2005 has created new control problems because of its propensity to develop strong insecticide resistance. As a result, there is a strong need to monitor the movement of this biotype and to be able to rapidly distinguish between the native A biotype, and the invasive B and Q biotypes already in the U.S. As a result of this need, a rapid PCR-based technique was developed to allow individual whitefly testing for biotype identification. This test is rapid and relatively inexpensive and can be adapted by testing laboratories without extensive training. NP 304, Component II – Biology of Pests and Natural Enemies, Problem Area II (A) – Basic Biology.

Phylogeny of the Q biotype of Bemisia tabaci. Results of the analysis of the movement of the Q biotype into the U.S. using sensitive genetic markers, we have shown that it has entered the U.S. several times as distinct populations and the populations that exist in the U.S. have much greater genetic diversity than that observed for the established B biotype. Through extensive surveys from samples throughout the U.S., the Q biotype has not established in field populations and has only spread through greenhouse plant propagation systems. This data has been used in worldwide trade negotiations conducted to settle trade restriction issues being imposed to prevent the spread of B. tabaci and the plant diseases it vectors. NP 304, Component II – Biology of Pests and Natural Enemies, Problem Area II (A) – Basic Biology.

Attractants for Diaprepes root weevil. Olfactory responses of the Diaprepes root weevil to plant and conspecific odors using a gas chromatograph-coupled electroantennogram (GC/EAG) were studied. Plant volatiles were identified that elicit antennal responses, and at least two EAG-active volatile compounds produced by the weevil have been discovered and are now being tested in bioassays and wind tunnels studies. The objective of this work is to develop a chemical attractant for use in detection, monitoring, and control. An invention disclosure was submitted and approved describing the first chemical attractant for Diaprepes. NP 304, Component VI – Integrated Pest Management Systems and Areawide Suppression, Problem Area VI (A) – Sampling Methods, Detection and Monitoring.

Monitoring Asian citrus psyllid. Studies were conducted to compare yellow sticky card traps, blue sticky card traps, and various different traps for monitoring adult Asian citrus psyllid in citrus. A stem tapping method was also investigated. Yellow sticky traps captured significantly more adults than blue sticky traps in one study but not in another. Each of these traps captured significantly greater numbers of adults than any of the other traps studied, the latter of which appeared to have no value for monitoring the psyllid. Yellow and blue sticky traps were equally effective in detecting the presence of adults in trees. Tap sampling was easy to conduct and provided relatively good detection of trees infested by adults. An advantage to stem tap sampling over sticky trap sampling is that tap sampling provides information on the presence and relative abundance of adults during a single visit to a block of trees while sticky trap sampling requires two visits. NP 304, Component VI – Integrated Pest Management Systems and Areawide Suppression, Problem Area VI (A) – Sampling Methods, Detection and Monitoring.

Chemical control of the Asian citrus psyllid. The effects of a kaolin-based hydrophilic particle film, Surround WP, on the biology and behavior of the Asian citrus psyllid were studied, and population densities of the psyllid in citrus subjected to monthly applications of Surround WP were assessed. Surround WP in water applied directly was not acutely toxic to eggs, older nymphs or adults. However, presence of the dried particle film on leaves interfered with the ability of adults to grasp, walk and lay eggs on citrus leaves. In field studies, cumulative reductions of 60 to 78% in adult numbers were observed in treated trees compared to untreated trees. Numbers of eggs and nymphs were reduced by 85 and 78%, respectively, in trees treated with particle film. The suppressive effects of a Surround treatment against adult psyllids were degraded by rain. NP 304, Component V – Pest Control Strategies, Problem Area V (D) – Chemical Control.

Population ecology of the pink hibiscus mealybug. Studies on the seasonal ecology of the mealybug based on adult males captured in pheromone traps indicated that the pink hibiscus mealybug was consistently most abundant during late summer and early fall with peak populations occurring anytime during late August through early October. Populations of the mealybug were consistently low during winter and spring from January through mid April. The best time to initiate an applied management program for the mealybug may therefore be during the summer. NP 304, Component III – Plant, Pest and Natural Enemy Interactions and Ecology, Problem Area III (B) – Population Studies/Ecology.

5.Significant Activities that Support Special Target Populations

6.Technology Transfer

Number of invention disclosures submitted1
Number of non-peer reviewed presentations and proceedings23

Review Publications
Hall, D.G., Childers, C.C., Eger, J.E. 2007. Binomial sampling to estimate citrus rust mite (acari: eriophyidae) densities on orange fruit. Journal of Economic Entomology. 100: 233-240.

Lapointe, S.L., Borchert, D.M., Hall, D.G. 2007. Effect of low temperatures on mortality and oviposition in conjunction with climate mapping to predict spread of the root weevil Diaprepes abbreviatus and introduced natural enemies. Environmental Entomology. 36(1):73-82.

Schuster, David, Howard Frank, Joe Funderburk, Phil Stansly, Cindy McKenzie, Jane Polston, Phylis Gilreath, and Amanda Hodges. 2006. Pest Managment pp. 41-90. In: J.L. Gillett, H.N. HansPetersen, N.C. Leppla, and D.D. Thomas (eds.). Grower's IPM Guide for Florida tomato and pepper production. University of Florida, Gainesville, FL (Book Chapter) pp 259

Shatters, R.G., Boykin, L.M., Lapointe, S.L., Hunter, W.B., Weathersbee III, A.A. 2006. Phylogenetic and structural relationships of PR-5 gene family reveals an ancient multigene family conserved in plants and select animal taxa. Journal of Molecular Evolution. 63(1):12-29.

Sinisterra, X.H., Shatters, R.G. Jr, Hunter, W.B., Powell, C.A., McKenzie, C.L. 2006. Longevity of ingested mRNA transcripts in the gut of a homopteran (Bemisia tabaci): avoiding experimental artifacts. Entomologia Experimentalis et Applicata. 121(3): 273-279

Hall, D.G., Lapointe, S.L., Wenninger, E. 2007. Effects of a particle film on biology and behavior of Diaphorina citri (Hemiptera: Psyllidae) and its infestations in citrus. Journal of Economic Entomology. 100:847-854.

Weathersbee III, A.A., Lapointe, S.L., Shatters, R.G. 2006. Activity of Bacillus thuringiensis isolates against the root weevil, Diaprepes abbreviatus (Coleoptera: Curculionidae). Florida Entomologist 89:441-448.

Hall, D.G., Albrigo, L.G. 2007. Estimating the relative abundance of flush shoots in citrus, with implications on monitoring insects associated with flush. HortScience. 42:364-368.

Hall, D.G., Hentz, M.G., Ciomperlik, M.A. 2007. A comparison of traps and stem tap sampling for monitoring adult Asian citrus psyllid (Hemiptera: Psyllidae), in citrus. Florida Entomologist. 90:327-334.

Last Modified: 4/19/2014
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