2011 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. Documents SCA with U of AZ.Formerly 5347-22620-020-03S (11/10).
Observational feeding bioassays were conducted with Lygus hesperus on four new crops, lesquerella, guayule, camelina and vernonia. Insects preferred feeding on fruiting structures of all crops but less so on camelina. A four year field study was completed to examine the impact of Lygus bugs on lesquerella yield and seed oil content. While Lygus bugs damage the flowers and fruiting pods of lesquerella, this damage did not consistently translate into reductions in seed yield or seed oil content. Results suggest that if the crop is established and managed with optimal agronomic practices, Lygus bugs may not significantly limit yield in this crop. However, the crop could act as a regional source of Lygus bugs and thus affect management of surrounding crops such as alfalfa and cotton. Flight assays were conducted to compare flight performance of diapausing and non-diapausing Lygus bugs. Non-diapausing females took more flights and flew a great distance than diapausing females; there were no differences between diapausing and non-diapausing males and males were much less active than females overall. Spatial analyses of Lygus bugs at the landscape level indicate that cotton and uncultivated habitats act as sinks (net importer) for the insect and that seed alfalfa act as a source (net exporter), while pest abundance is modified by delayed planting date. 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. 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. Based on experimental spatial 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 the entire play area. Several pilot workshops have been conducted with several groups of growers and pest control advisors and 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, the benefits of optimizing community outcomes through communication and cooperation in managing planting patterns over large landscapes. Draft guidelines were disseminated to growers via Extension circulars, advisories, in-field workshops, and presentations to growers including farmers in Mexicali, Mexico. Validating experiments are planned for these guidelines in replicated field assessments and commercial grower fields in 2011. These guidelines will be the focus of a new popular short article series, Field Crops IPM Shorts (URL: http://ag.arizona.edu/crops/cotton/agronomic_ipm.html ). One output also addressed the impact of high cotton prices on economic thresholds used to control Lygus (and whiteflies), http://ag.arizona.edu/crops/cotton/files/NewThresholdsVF.pdf.
The ADODR monitored activities for the project by frequent meetings, site visits, and emails with the cooperating scientist.