Project : USDA ARS

ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Pest Management and Biocontrol Research » Research » Research Project #428993

Research Project: Ecologically Based Pest Management in Western Crops Such as Cotton

Location: Pest Management and Biocontrol Research

2019 Annual Report

Accomplishments
1. Novel mechanism of pink bollworm resistance to Bacillus thuringiensis (Bt) crops. Transgenic crops engineered to produce insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) provide many benefits including pest suppression, increased yields and farmer profits, reduced conventional insecticide use, decreased harm to non-target species, and enhanced biological control. However, pest resistance to Bt crops decreases such benefits. Pink bollworm is a global pest of cotton and resistance to the toxins of Bt cotton involve mutations and/or cellular trafficking of a cadherin receptor protein thought to prevent toxin binding to the insect midgut. Findings by an ARS scientist from Maricopa, Arizona, and researchers from the University of Arizona, show that the down-regulation of cadherin transcript and protein is responsible for loss of the available receptor. These findings reveal the remarkable adaptability of pink bollworm and other major pests to evolve resistance to Bt toxins via both qualitative and quantitative changes in receptor proteins and demonstrates the challenges for monitoring and managing resistance to Bt crops. The results are valuable for scientists concerned with understanding the mechanisms of resistance, for private industry for developing new commercial strategies to target pests, and for government authorities responsible for regulating transgenic crops.

2. Flight mill technology for the study of insect flight behavior. Dispersal is a key component in the population ecology and dynamics of insects, yet it remains one of the most difficult and intractable ecological processes to study in the field. Thus, many researchers have looked to laboratory methods for investigating the many factors that influence an insect’s ability to move within its environment. A scientist in Maricopa, Arizona, reviewed and synthesized the global literature on the development, use, and data interpretation of insect flight mills for the study of flight behavior. The study provided details on the construction and operation of a flight mill developed by the ARS scientist, including access to websites and videos. The technology has been used by numerous scientists studying a wide range of insect pests and is of substantial value to those interested in used flight mills for the study of insect dispersal.

3. Efficacy and safety of Bacillus thuringiensis (Bt) eggplant in Bangladesh. Bangladesh approved the commercial cultivation of Bt eggplant in 2014 and is the first developing nation in the world to introduce a Bt vegetable crop. Bt eggplants produce an insecticidal protein that is toxic to certain caterpillar pests. A researcher in Maricopa, Arizona, in collaboration with scientists from Cornell University and the Bangladesh Agricultural Research Institute, conducted replicated plot studies at two sites in Bangladesh to assess the efficacy and environmental safety of four Bt eggplant varieties. All varieties provided high levels of control of the eggplant fruit and shoot borer, a key caterpillar pest, and resulted in substantial economic returns relative to conventional practice. In addition, there was no evidence that Bt eggplant negatively affected other arthropods, including non-target pests and many species of natural enemies. Results demonstrated that this highly selective and effective crop will benefit growers, consumers and the environment in Bangladesh.

4. Thermal ecology of Lygus hesperus. Irrigation management strategies in western crops are changing because of the increasingly limited supply and higher cost of water. Alternative strategies such as deficit irrigation result in periodic, moderate drought stress in cotton, and corresponding increases in canopy temperatures. Previous reports indicate an association between limited irrigation and lower Lygus population levels in cotton, but the controlling mechanism is not known. Knowledge of arthropod responses to changing irrigation practices can enhance practices supporting a successful integrated pest management program. ARS researchers at Maricopa, Arizona, showed that development of Lygus eggs, nymphs, and adults were similar between constant and variable temperature regimes when temperatures were moderate, but that low and high-variable temperature regimes typical of field conditions supported development at rates different from those observed under constant temperatures. These findings suggest that survival and development of overwintering Lygus are enhanced by daily variations in temperatures, and both are likely higher in the field than constant temperature studies have indicated.

5. Arthropod predation monitoring. Knowledge of arthropod predation is an important component of a successful integrated pest management program. The most popular indirect method to assess predation is by examination of a predator’s stomach contents for the presence of pest-specific DNA; however, this method is time consuming, costly, tedious, and has many limitations. An ARS researcher at Maricopa, Arizona, developed an immunological assay for detecting a unique protein biomarker applied to any targeted pest species that can be readily transferred to a predator during feeding. Studies revealed that the technique is effective at detecting protein-marked prey remains in the guts of all types of predators and that the protein marks should be applied internally to the prey (when possible) to maximize detection while minimizing the risk of false positive assay errors. The assay is less expensive, time consuming, and tedious than the conventional DNA assay method. Refinement of this gut assay procedure provides researchers with a reliable alternative technique for evaluating prey choice of predators in agroecosystems.

6. Tracking the dispersal of arthropod predators and parasitoids. Knowledge of arthropod predator and insect parasitoid dispersal patterns is critical for effective biological control of grape pests. An ARS researcher at Maricopa, Arizona, and scientists at the University of California, Riverside, developed a novel “triple mark” method to track arthropod movement in a vineyard containing a buckwheat cover crop. Arthropods were marked directly in the buckwheat plots using a “triple mark" solution containing yellow dye, casein protein, and albumin protein. The abundance of marked and unmarked natural enemies was recorded at a gradient of distances from the treated buckwheat plots into the vineyard. Results revealed that buckwheat refuges planted every sixth or tenth row within the vineyard could increase the biological control services rendered by the natural enemy complex on key grape pests.

7. Host preference and dispersal of spotted wing Drosophila. The spotted wing drosophila (SWD) fly is one of the worst invasive pest species in the U.S., in part because it feeds on the fruit of many different types of economically important crops (e.g., blueberry, strawberry, cherry, etc.). Knowledge of its host preference and dispersal ability are important for effective management. ARS researchers at Maricopa, Arizona, and Michigan State University, used protein marking to examine the movement of SWD from wild host plants in the landscape surrounding blueberry farms. Results identified five commonly infested wild fruits (honeysuckle, wild blackberry, wild raspberry, autumn olive, and American pokeweed) and showed that SWD disperses at an even rate throughout the blueberry farms. Moreover, early season flies were less likely to remain in the marked host compared to late season flies. Findings highlight the importance of wild hosts on local pest pressure from SWD and suggest that wild host management should be considered as part of integrated strategies for reducing the economic impacts of this pest.

U.S. DEPARTMENT OF AGRICULTURE

Pest Management and Biocontrol Research: Maricopa, AZ