2012 Annual Report
1a.Objectives (from AD-416):
To study, through both laboratory and field investigation, the physiology, biochemistry, biology, ecology, and control plant bugs on various host crops in the arid southwestern USA with the goal of developing environmentally sound and sustainable pest management strategies.
1b.Approach (from AD-416):
Laboratory studies will focus on elucidating the feeding physiology and biochemistry of plant bugs feeding on cotton and other hosts. Specific biochemical pathways will be determined and evaluated and molecular methods will be used to identify potential genetic based methods for disrupting these pathways (e.g. RNAi). The life history of plant bugs on new industrial crops will be quantified under controlled conditions. The potential impact of plant bugs on yield and quality of new industrial crops will be investigated in the greenhouse and field using inclusion cages and field manipulation of plant bug populations.
This Special Cooperative Agreement is in support of Objective 3 Characterize flight behavior and dispersal of insect pests and natural enemies; elucidate relationships among landscape structure, pest and natural enemy biology and dispersal behavior, Subobjectives 3.1 Characterize the flight behavior of Latrodectus (L.) hesperus relative to environmental factors, 3.2 Quantify within and between crop movement of L. hesperus and 3.3 Quantify crop source-sink relationships for arthropod predators inhabiting cotton within the agroecosystem, and of Objective 5 Refine insecticide-based management strategies; characterize factors influencing resistance to chemical insecticides and insecticidal proteins in transgenic crops; evaluate insecticide selectivity; support post-eradication pink bollworm resistance monitoring in Bt cotton, Subobjective 5.1 Evaluate insecticide selectivity in the cotton system. Flight assays were conducted to compare flight performance of Lygus bugs over a range of temperatures from 16C to 30C. Little activity was observed at the temperature extreme suggesting that the insect has a narrow physiological range for flight. Additional flight assay studies are underway to examine the role of host plant. Insects are being reared from eggs on cotton, alfalfa, guayule, lesquerella or camelina and then assayed for flight behavior. A two year field study was completed and showed that well-watered cotton facilitates higher Lygus bug populations while water-stressed cotton reduces pest populations. These relationships were not altered by the kind of insecticide (selective or broad-spectrum) used to manage Lygus but selective options provided better pest control, enhanced yields, and conserved natural enemies. This enables growers to make better decisions with regard to crop production and pest control. Spatial analyses of Lygus bugs at the landscape level are being conducted on data from Arizona. Results from companion studies in California indicate that cotton and uncultivated habitats act as sinks (net importer) for the insect and that seed alfalfa acts as a source (net exporter), while pest abundance is modified by delayed planting date. These studies show that the abundance of Lygus in a specific cotton field can be predicted in future years by the area of cotton, uncultivated habitats and seed alfalfa within 2.75 km and knowledge of planting date. Additional analyses are underway to examine source and sink relationships of natural enemies of Lygus bugs relative to cotton and other crops at the landscape level using data from California and Arizona. Based on experimental data above, a game training exercise was developed so that growers can interact in a virtual farming community and make planting and control decisions that impact broader Lygus distributions and severity over an entire region. Several additional workshops have been conducted with growers and pest control advisors. At the workshops they learned about the role of source and sink crops for Lygus, the economic consequences of Lygus relative to crop placement and treatment threshold choice, and the benefits of optimizing community outcomes through communication and cooperation in managing planting patterns over large landscapes. Lygus management demonstration projects were established in grower fields in Arizona and Mexicali. Guidelines were disseminated to growers via Extension circulars, advisories, in-field workshops, and presentations to growers including some in Mexicali, Mexico. These guidelines are part of a new popular short article series, Field Crops IPM Shorts (URL: http://ag.arizona.edu/crops/cotton/agronomic_ipm.html) initiated in 2011. Outputs to date include shorts on sweep sampling, decision aids, insecticide options with emphasis on selective control, and a variety of circulars on key arthropod predators important to control of Lygus and other cotton pests. Most of these have been translated into Spanish.