BIOCHEMISTRY, PHYSIOLOGY, BIOLOGY, ECOLOGY, AND CONTROL OF PLANT BUGS IN THE WESTERN U.S.
2010 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.
Lygus hesperus mating status had no effect on flight initiation or orientation to a vegetative cue and flight initiation of both sexes declined with wind speed. Females took a greater number of flights and flew greater total distances at 25C compared with 20C. Males flew less frequently and covered less distance than females. Studies at 30C and 16C are underway. L. hesperus adults and nymphs spend 28-32% of their time feeding on various plant structures. Adult feeding assays were completed on camelina and analyses are pending. Development times of L. hesperus were similar on alfalfa and lesquerella but longer on guayule and camelina. Survivorship was 73-85%, on most plants but dropped to 62% on camelina. Lesquerella is an excellent host while camelina is a poorer host. Feeding and oviposition choice tests showed that L. hesperus readily feed and oviposit on each plant species, but prefer vernonia>lesquerella>camelina. Field studies show that damage to fruiting structures are correlated with Lygus bug density but that damage to these structures leads to variable effects on yield and seed oil quantity. The final year of study also shows that timing of damage (early season vs. late season) is inconsequential. Overall, Lygus is not likely to be a limiting factor in lesquerella production. Lesquerella is, however, likely to be a sink for Lygus during the later winter and early spring and a source of Lygus in late spring. With alfalfa as a bridge crop, the growth of populations in lesquerella could influence dynamics in nearby cotton. Community analyses indicate that the new insecticides flonicamid and metaflumizone selectively suppress Lygus bug while having little impact on predaceous arthropods.
Within-crop and intercrop movement of Lygus and associated natural enemies among cotton, alfalfa, guayule and lesquerella using multiple protein marks was quantified. Eleven mark-capture studies were completed over a two year period covering various stages of crop phenology. Insect samples have been assayed and data have been compiled for analysis. Mark-capture studies between strips of alfalfa planted within organic strawberry fields showed that the vast majority of Lygus remain in the alfalfa and very few dispersed more than 5.0-m into the surrounding strawberries. Further mark-capture field studies are quantifying Lygus and natural enemy dispersal patterns between the natural weed flora surrounding organic strawberry fields. All arthropod samples have been assayed and data are being compiled for analysis.
The ADODR monitored activities for the project by meetings, site visits, and emails with the cooperating scientist.