Location: Insect Behavior and Biocontrol Research2013 Annual Report
1a. Objectives (from AD-416):
1. Develop habitat manipulation strategies as components of IPM programs for polyphagous pests through behavioral and ecological studies of their interactions with host plants and natural enemies. 2. Develop “push – pull” strategies for whitefly management that integrate plant-based pest repellents and natural enemy attractants. 3. Develop and refine control strategies for invasive species infesting non-traditional agricultural settings, in particular the Argentine cactus moth and Chinese tallow.
1b. Approach (from AD-416):
We will determine how polyphagous thrips select and utilize host plants, and how these responses may be manipulated to reduce pest thrips within crops. We will use a model system consisting of tomato and 4 potential trap crops and varying fertilization regimes to test thrips responses to host plant quality as a means to develop trap cropping systems. Systematic surveys of weeds will be used to assess their role as reservoirs in the spread of thrips-vectored viruses. Host plants effects on acquisition and transmission of Tomato Spotted Wilt Virus (TSWV) by thrips will be tested by using various plants as acquisition sources and inoculation targets. Tropical soda apple will be used as a model system to determine how biological control of an invasive weed may reduce the spread of TSWV. Field studies will be used to determine if the presence of the banker plants can increases predation on thrips. Push-pull strategies for the management of whiteflies will be developed. Certain plants and extracts from them will be tested in the field and lab to determine if they can repel whiteflies from target crops. Bioassays of other plants will be used to identify those that are good reservoirs for predators of whiteflies. Combinations of repellent plants and banker plants for predators will be studied to optimize push-pull strategies for whitefly management. The sterile insect technique for management of invasive lepidopteran pests will be improved by development of bioassays that measure field performance of sterile moths. Lab bioassays will then be developed as proxy measures for field performance bioassays to gauge sterile insect performance. Existing pheromone trapping for monitoring cactus moth populations will be improved through calibrating captures with population size. Life table studies will be conducted in the cactus moth’s invaded range to identify stages most amenable for biological control. Additional biological control will be assessed by testing non target risks of Trichogramma pretiosum, a candidate for inundative releases. Population dynamic studies of Chinese tallow will be conducted to identify what types of biological control agents may have the greatest impact on the weed.
3. Progress Report:
Progress was made in all the major goals of 6615-22000-026-00D, “Biologically-based management of invasive insect pests and weeds”: improvement of IPM through manipulation of tritrophic interactions, development of push-pull systems for whiteflies and control of invasive species in non-traditional agricultural settings. In particular, companion plants were identified that reduced thrips and their vectored disease, tomato spotted wilt (TSWV), in tomatoes, peppers and cucumbers. Four different cover crop systems were also examined for enhancement of beneficial insects and biotic resistance against pest thrips and the spread of TSWV in vegetable crops. These were: i) conventional black plastic mulch; ii) traditional cover crop, with spring cash crops transplanted into overwinter leguminous cover crops; iii) transitional cover crop, with the cash crops planted on black plastic overlaid the cover system; iv) beneficial insect cover crop system. Additional evidence was obtained that giant red mustard repelled whiteflies and squash could serve as a trap crop. Sterile insect techniques (SIT) and related technologies for invasive cactus moth control were further developed. Laboratory and field bioassays evaluated the quality of moths in the SIT program, and provided feedback for protocol changes in rearing and handling. Classical biological control is highly sustainable and the potential of a new species of Argentine wasp for cactus moth biological control was evaluated. Host specificity tests on native North American lepidopteran species are ongoing. Studies were conducted in Argentina on a formulation of an ARS-developed synthetic female cactus moth sex pheromone as a means to disrupt mating. In pheromone-treated plots, mating and oviposition were significantly reduced compared to untreated plots.
1. Components of a push-pull system. There is increasing interest in use of non-chemical methods to control whiteflies, especially in organic and sustainable farming. Response-tests of whiteflies to various plants and easily obtained commercial oils found that giant red mustard plants, mustard oil and squash crop-traps are promising components of a push-pull system to control whitefly in vegetables. Several perennial and annual weedy plants may “pull” hover fly generalist predators into crop environments. Such native plants could provide food for adult hover flies and so help maintain high predation levels in farmscapes.
2. Biological control of the cactus moth. The invasive Argentine cactus moth continues to spread in the southern U.S. attacking and destroying prickly pear cactus. A newly discovered and host-specific Argentinean parasitoid wasp is host-specific in its native range and is being evaluated as a biological control agent. Collections of the wasp were made in Argentina and brought to a quarantine facility in Gainesville, Florida, where host specificity tests on native North American lepidopteran species are being conducted. If continued research proves the wasp to be a safe biological control agent, it represents a self-perpetuating control option and practical approach to protecting the vast native prickly pear cactus in the desert Southwest and Mexico against an established population of invasive cactus moth.
Baker, G.T., Hight, S.D., Brown, R.L. 2012. External morphology of the egg of the native (Melitara prodenialis) and exotic (Cactoblastis cactorum) cactus moths (Lepidoptera: Pyralidae. Proceedings of the Entomological Society of Washington. 114(4):433-438.