Location: Insect Behavior and Biocontrol Research2012 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:
Objective 1: Two field trials were conducted, in collaboration with scientists from the University of Florida and Glades Crop Care to assess the utility of push-pull strategies for the managment of western flower thrips and tomato spotted wilt virus in tomato and pepper crops. Because of their attractiveness to pest thrips, sunflowers and Bidens alba were used as plants to attract thrips away from target cash crops. These plants are also attractive to competitor thrips and predators of western flower thrips. Ultraviolet reflective mulches and kaolin, a clay-like material that can be sprayed on crop plants, were used as repellents to push thrips away from target cash crops. The results to date indicate that these push and pull tactics may be beneficial in thrips managment programs by deterring pest thrips and enhancing local populations of non-pest competitor thrips and predatory insects that suppress western flower thrips populations. Objective 2: The ficus whitefly is an emerging pest of ornamental ficus in Florida. To better characterize the potential for biological control of the ficus whitefly, collaborative research with scientists from the University of Florida is being conducted with biological control agents already established in Florida. Predation rates of the coccinellid Delphastus catalinae on different stages of the ficus whitefly have been analyzed. Both adult and larvae of Delphastus preyed on substantially more ficus whitefly eggs than on small or large nymphs. Objective 3: Significant progress was made to develop biological control strategies for the invasive Argentine cactus moth. In collaboration with Argentine scientists, a parasitic wasp is being studied for its host specificity and suitability as a classical biological control agent. A wasp colony is being maintained for future shipment to the U.S., and protocols have been developed for rearing the wasp and for testing non-target caterpillars as potential hosts. Host range testing on other Argentine cactus-feeding moth species has proven the wasp to be host specific. Morphological and molecular studies have determined that the wasp is new to science and a description of the species has been prepared. Once a permit is obtained to bring the wasp into USA quarantine, continued host range testing will be conducted on North American cactus-feeding moths. If continued research proves the wasp to be an effective biological control agent, it would represent a self-perpetuating control option and practical approach to protecting native prickly pear cactus in the desert Southwest and Mexico.
1. Integration of western flower thrips biological control agents. Because of problems with insecticide resistance and related issues, there is a critical need to develop alternative managment methods for the western flower thrips, a globally important invasive pest that attacks a wide range of horticultural and agronomic crops. Researchers from ARS, Tallahasse, FL, and the Chinese Academy of Agricultural Sciences identified a strain of fungal pathogen that is highly virulent to western flower thrips but is not virulent to a key predator of thrips, the minute pirate bug. The fungal pathogen can be applied as a biopesticide for short-term supression of western flower thrips without disrupting the longer term of control that minute pirate bugs can provide. These findings offer potential to synergize these different types of biological control agents to improve management of western flower thrips in an environmentally-friendly manner.
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. Working with collaborators in Argentina, a parasitic wasp is being evaluated as a biological control agent. Preliminary research has identified this wasp to be new to science and potentially host specific to the pest cactus moth species. 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 prickly pear cactus in the desert Southwest and Mexico against an established population of invasive cactus moth.
3. New pheromone for cactus moth monitoring. The ARS-developed synthetic female cactus moth pheromone does attract male cactus moths into monitoring traps, but several other moth species are also attracted and captured. Improvement to the ARS pheromone was identified in field trials; a two component blend that caught more target cactus moths and fewer non-target moths than the currently used blend. A better pheromone will improve the traps usefulness to predict cactus moth presence in the environment and make identification of captured moths easier by reducing the number of non-target moths caught in traps.
4. Repellents for whitefly management. Whiteflies are major insect pests of horticultural crops, and there is increasing interest in alternatives to synthetic insecticides for whitefly managment, especially for organic and sustainable farms. ARS scientists at Tallahassee, Florida, and Charleston, South Carolina, tested various plant products and commercial oils that are readily available to growers for their repellency to whiteflies. Behavioral tests under laboratory conditions have shown that plant oils such as mustard, garlic, and horticultural oil, significantly reduce setting by whiteflies on treated crop plants. Results from our studies may provide growers with non-insecticidal alternatives for the management of whiteflies in vegetable crops.
Manrique, V., Diaz, R., Hight, S.D., Overholt, W.A. 2011. Evaluation of mortality factors using life table analysis of Gratiana boliviana, a biological control agent of tropical soda apple in Florida. Biological Control. 59(3):354-360.