Project Overview
Commodities
- Nuts: pistachios
Practices
- Crop Production: alley cropping, cover crops
- Education and Training: on-farm/ranch research
- Farm Business Management: budgets/cost and returns
- Natural Resources/Environment: biodiversity, habitat enhancement, strip cropping
- Pest Management: biological control, chemical control, cultural control, economic threshold, field monitoring/scouting, integrated pest management, row covers (for pests), trap crops
- Production Systems: agroecosystems
- Sustainable Communities: sustainability measures
Abstract:
The leaffooted bug, Leptoglossus zonatus, is an important pest of tree nut crops in California. In pistachio, feeding from leaffooted bug can lead to significant damage and loss of nut crops. Given the pest’s rapid and unpredictable movement into orchards, and lack of effective monitoring tools to detect such migrations, growers often rely extensively on pesticide applications to control the pest, commonly at first perceived risk of pest activity. This management approach can be both economically costly for growers and environmentally unsustainable. In 2018-19, our group initiated a collaborative project with a large tree nut producer to explore the use of summer cover crops as an integrated pest management (IPM) strategy for large hemipteran pests. Over a two-year period, we assessed the influence of irrigated groundcover strips in the row middles on pest damage and biological control of leaffooted bug.
In this study, a combination of field and laboratory studies were used to evaluate the effect of flowering groundcovers on the reproductive fitness of the leaffooted bug egg parasitoid, Hadronotus pennsylvanicus, and the abundance of its host L. zonatus in pistachio. Evaluated groundcovers included oat (Avena sativa L.), cowpea (Vigna unguiculata L.), white mustard (Sinais alba L.), and buckwheat (Fagopyrum esculentum Moench). Under laboratory conditions, buckwheat provided the greatest benefits to female H. pennsylvanicus longevity. While all floral diets improved female fecundity under laboratory conditions, there was no difference in the total offspring produced per female. In field trials, flowering groundcovers did not influence the abundance of H. pennsylvanicus nor parasitism rates of L. zonatus. While the availability of diet can improve the lifetime reproductive fitness of H. pennsylvanicus, the addition of groundcovers in a pistachio orchard did not enhance populations of H. pennsylvanicus nor biological control of L. zonatus. Findings from this study suggest that the use of flowering groundcovers to improve biocontrol in pistachio is likely not a viable solution to sufficiently suppress L. zonatus populations and meet the current production demands of California tree nut production.
Project objectives:
Objective 1: Evaluate egg parasitoid Hadronotus pennsylvanicus as a biological control agent to leaffooted bug Leptoglossus zonatus.
Objective 2: Measure the impact of diet quality on life parameters of leaffooted bug parasitoid Hadronotus pennsylvanicus.
Objective 3: Evaluate the influence of groundcovers on biological control of leaffooted bug in pistachio.
(Objective 3A) Monitor seasonal abundance of leaffooted bug and their key natural enemies in pistachio with and without groundcovers.
(Objective 3B) Assess parasitism and predation of leaffooted bug in plots with and without trap crops.