Location: Insect Behavior and Biocontrol Research2013 Annual Report
1a. Objectives (from AD-416):
1. Genetics: Identify developmentally significant genes from whole genome and transcriptome sequencing projects that may be targeted or manipulated in transgenic and nontransgenic insect strains for biological control. Test conditional lethal systems using cell death genes and microRNAs targeted to embryos and vital processes in tephritids and lepidopterans and develop germ-line transformation for the cactus moth and Asian citrus psyllid. 2. Detection and attraction: Develop chemical and acoustic detection and attraction systems for pest species and natural enemies: specifically develop trapping systems using floral-derived volatiles to monitor and/or eliminate pest populations and monitor dispersal of augmented parasitoids, detect acoustic signals produced by cryptic/hidden pests for targeted control, and improve detection efficiency through automation. 3. Biological control: Develop strategies for use of parasitoids and predators in IPM of insect pests through behavioral, ecological and physiological studies of their feeding, mating,dispersal and oviposition: Specifically target conservation biological control on overwintering reservoirs of migratory fall army worm and other pests; develop thelytokous strains of fruit fly parasitoids for augmentative biological control, and develop Asian citrus psyllid diets that will facilitate the mass-production of hosts for mass-rearing parasitoids for augmentative parasitoid releases and other forms of biologically-based control; and develop predictive models of pest migration that incorporate climate-change and facilitate the targeting of vulnerable populations.
1b. Approach (from AD-416):
New biocontrol strategies will be based on transgenic strains that confer conditional lethality, so that insects can be mass reared under permissive laboratory conditions, while their offspring die in the field under nonpermissive conditions. The tetracycline-suppression (tet-off) embryonic conditional lethality system consists of an embryonic driver construct and a lethality inducing effector construct both integrated by piggyBac transposition into a host genome. To develop RNA inhibition (RNAi) strategies for the conditional genetic constructs gene homologues will be identified, then inhibitory FAW RNAi constructs will be incorporation in artificial media. Recombinants expressing these constructs wiil be tested and effective constructs introduced. To precisely target populations of hidden/cryptic pests distinctive spectral and temporal patterns of acoustic signals will be identified. Insect detectability will be optimized by constructing customized attachments or waveguides connecting the sensors to the substrates. Automated systems can be developed that remotely detect, identify, and count specific pests based on the spectral and temporal patterns of signals. An automated system for trapping C. capitata will consist of a lure and a microphone connected to a signal acquisition andanalysis system attached by cable or wireless to a computer. To develop food/host based attractants for opiine braconid fruit fly parasitoids to monitor augmentative releases and to stimulate oviposition volatiles produced by fruit fly larvae, infested fruits and nectar-sourcesare parasitoids to locate hosts, host-habitats and adult food will be identified and formulated into appropriate lures and additives. To develop floral attractants and pheromones for monitoring and/or control of adult lepidopterous pests research will concentrate on phenylacetaldehyde (PAA) plus ß-myrcene, cis-jasmone, benzyl acetate and additional candidate identified by field surveys. Lures will be first tested in flight tunnels and then in the field. To develop thelytokous strains of fruit fly parasitoids for augmentative biological control, Wolbachia-infected parasitoid surveys will be based on the theory that asexual populations are more persistent in biologically less diverse environments. To develop improved control strategies for lepidopteran pests that recruit natural enemies, combinations of resistant crops and plants supporting natural enemies will be compared in the field using sentinel plants and a split plot arrangement of treatments. To predict the spatial and temporal shifts in infestations of migratory noctuid pests that result from climate change and to target controls, genetic markers will be used to identify source populations from which migratory pathways can be derived, and historical changes in these pathways explained with meteorological and climatic data.
3. Progress Report:
Progress was made in the all the major goals of 6615-22000-025-D “Biologically-Based Technologies for Management of Crop Insect Pests in Local and Area-Wide Programs”: identification of pest populations and their dispersal, discovery of new biological control agents, their mass-rearing and release. In particular, a parasitic wasp was genetically modified for the first time, laying the foundation for a new generation of genetic studies of parasitic Hymenoptera and ultimately novel biological control approaches. Research advanced genetic modifications that induce fruit fly male sterility for Sterile Insect Technique (SIT) programs, but which do not require debilitating irradiation. Other genetic modifications produced fruit fly strains whose females fail to develop outside artificially permissive conditions and so yield all-male cohorts for (SIT) programs. With collaborators in Mexico these strains are being further developed to control fruit flies of importance to both the USA and Mexico. The migrations of the fall armyworm were described over a wider, now international, area. More broadly obtained data will improve ongoing efforts to relate climate variables to the distributions of this and other migratory pests. Chemical attractants are not useful in some situations where pests are hidden and immobile, such as when they infest, grain or wood, but their presence can still be discovered through the sounds they make as they feed. Acoustic pest identification techniques continued to be perfected and applied domestically and overseas, particularly in regard to the invasive red palm weevil. Spectral sensitivity in the vision of the Asian citrus psyllid was documented. These colors will be incorporated into improved traps and minimized in citrus-hosts to produce plant resistance (low visibility). Fruit fly parasitoid fruit-based oviposition stimulants were examined which could improve production in mass-rearing facilities. Continuing surveys found that certain plants attract hover fly predators of aphids. Such plants could conserve and concentrate natural enemies by providing adult food.
1. Genetic transformation of a model-parasitoid. A system to genetically modify a parasitoid wasp, Nasonia vitripennis, was developed. This species is used internationally for both biological control and laboratory studies. Genes from the wasp were identified and cloned into both somatic and germline transformation vectors and functionality of the vectors was demonstrated in the wasp as well as Drosophila. Genetic transformation of N. vitripennis will allow the introduction of visual genetic markers and growth enhancement factors to improve their efficacy in livestock-pest control programs.
2. New gene-transfer system. The position of genes within the genome can influence their expression and the likelihood of their being combined with other genes during sexual reproduction. Thus the ability to precisely place genes during transfers into a new genome is of considerable importance. A gene-transfer vector that allows gene targeting to a specific genomic insertion site was successfully tested for the first time in a non-drosophilid insect, the Caribbean fruit fly, Anastrepha suspensa. It will be a valuable tool for functional genomic analysis, and the efficient creation, testing and modification of genetically engineered insects for improved biologically-based population control programs.
3. Climatic influences on migratory moths. Targeting and then controlling migratory populations of the fall armyworm at their source would prevent infestations over much of eastern North America. Climate change is anticipated to alter meteorological patterns and weather systems with potentially significant changes in the timing and direction of the migration. The second year (of five) of fall armyworm collections included specimens obtained from previously unexamined areas in Mexico and the Caribbean and were recorded in the PestWatch database http://www.pestwatch.psu.edu/). Ultimately, the relationship between genetic constitution, migration and weather will facilitate development of strategies to monitor, predict, and ultimately control the movements of these highly mobile pests.
4. Detection and monitoring of infected red palm weevil. Invasive red palm weevil seriously affects palms in an increasing numbers of countries and threatens those in the USA. Acoustic methods were developed for monitoring the efficacy of a control program directed against the red palm weevil. In Spain, larvae inside palm wood were treated with entomopathogenic fungi and then acoustically monitored as they suffered morbidity and death. Use of novel methods to follow the behavior of hidden insects will help identify optimal control techniques against these and other important invasive borers.
5. Conservation of predatory flies. Pests can be suppressed by increasing or concentrating natural enemies with the addition of non-crop plants to agricultural environments that provide shelter, food and alternative hosts. Hover fly larvae are important predators of soft bodied pests such as aphids but adults feed on flower nectar. Plants were identified that attracted particular species of hover flies in northern Florida, and incorporation of these plants, many of them native and requiring little input, could be part an integrated pest management program designed to protect crops, especially those grown under organic regimens.
6. Landscape modification to suppress pest migration. Fall armyworm seriously damages sweet corn in southern Florida during the winter, and starting in early spring, successive generations of moths move northward feeding on cover crops such as forage sorghums. Plots in Florida planted with forage sorghum or two alternative plant species, sunn hemp and cowpeas, were sampled to determine the number of pest caterpillars. Very low numbers of pest caterpillars were found in these alternative plants compared to the standard cover crop. The use of alternative cover crop plants has the potential to reduce fall armyworm populations over a large area and decrease the number of moths moving north each spring.
7. Visual attractants for psyllids. As the vector of the devastating disease, citrus greening, the Asian citrus psyllid continues to threaten new plantings of citrus in Florida and California. While surveillance of dispersing psyllids is critical for spray applications to protect citrus, monitoring methods remain limited. Laboratory studies conducted at ARS/Gainesville, Florida, revealed that LEDs of certain colors were highly attractive to both male and female psyllids. This information can provide the basis for enhancement of current traps for psyllid surveillance or perform as a component of a push-pull system for psyllid management.
Nagoshi, R.N., Paraiso, O., Brambila, J., Kairo, M.T. 2012. Assessing the usefulness of DNA barcoding to identify Oxycarenus hyalinipennis in Florida,a potentially invasive pest of cotton.. Florida Entomologist. 95(4):1174-1181.