1a. Objectives (from AD-416):
Objective 1: Determine biologically-based management programs using biological control agents and cultural controls. • Sub-objective 1A: Determine the potential of Habrobracon hebetor as a natural control of field populations of navel orangeworm. • Sub-objective 1B: Determine the feasibility of using a combination of sanitation and entomopathogenic nematodes for postharvest control of navel orangeworm in pistachios. • Sub-objective 1C: Disrupt symbiotic aspects of California grey ants (CAGA) with mealybug pests on grape vines to allow biological control of the mealybugs. Objective 2: Develop behaviorally based management programs using pheromone trapping, mass trapping, and mating disruption. • Sub-objective 2A: Develop attract and kill traps to control olive fruit fly in table olive orchards. • Sub-objective 2B: Determine efficacy for navel orangeworm control using mass trapping of males with sex pheromone. • Sub-objective 2C: Elucidate mechanisms of navel orangeworm mating disruption. Objective 3: Develop alternative physical treatments for fresh and durable commodities. • Sub-objective 3A: Determine potential of combinations of high temperature and controlled atmosphere for control of codling moth in walnuts.
1b. Approach (from AD-416):
Postharvest insects cause significant economic loss to the agricultural sector, both through direct damage by feeding or product contamination, and by the cost of control programs. The export trade of certain horticultural products may be affected as well, with importing countries requiring quarantine treatments to prevent the introduction of exotic pests. Of particular concern to agriculture in the Western U.S. are field pests such as the olive fruit fly (Bactrocera oleae), navel orangeworm (Amyelois transitella), various mealybugs, and codling moth (Cydia pomonella), and storage pests such as the Indianmeal moth (Plodia interpunctella). Processors rely largely on chemical fumigants such as methyl bromide for insect disinfestation, but regulatory, environmental and safety concerns mandate the development of non-chemical alternatives. This project addresses this problem with a broad collaborative approach, examining both preharvest, biologically based control strategies as well as physical postharvest disinfestation treatments. Areas of investigation include the development of attract and kill traps for control of olive fruit fly, improved field control of navel orangeworm through mating disruption, mass trapping, sanitation and entomopathogenic nematodes, control of vineyard mealybugs through reduction of ant populations, combining forced hot air with controlled atmospheres to disinfest walnuts of codling moth, and the potential of the parasitoid Habrobracon hebetor as a natural control agent for navel orangeworm and Indianmeal moth. New, non-chemical methods for control of these economically important pests will be the outcome of this research.
3. Progress Report:
This report documents progress for this new project, which started in May of 2013 and continues research from 5302-43000-034-00D, "Biological, Behavioral, and Physical Control as Alternatives for Stored Product and Quarantine Pests of Fresh/Dried Fruits and Nuts". Studies on Habrobracon hebetor as a biological control for navel orangeworm (NOW) were begun. Using traps baited with laboratory-raised Indianmeal moth and NOW, the parasites Habrobracon hebetor, Venturia canescens, and Mesostenus gracilis were recovered from all locations. Cultures of all 3 parasites were established. Studies were begun to determine the suitability of NOW as a host to H. hebetor. An important aspect of NOW control is postharvest sanitation to destroy infested unharvested nuts and remove them as resources for future egg-laying. Several pistachio orchards with high NOW pressure have been identified and are being monitored through harvest to determine the surviving population. Success of cultural and biological controls in reducing surviving NOW will be assessed. Because California grey ants protect mealybugs from natural enemies, intensive pesticide applications are needed to control both pests and ants. Colonies of both the ants and the mealybugs were established. Ant behavior with and without mealybugs were observed and cataloged. Elucidation of trail compounds can be used to lead ants to poison baits for control. These activities address objective one. A novel attract-and-kill trap was constructed of yellow corrugated plastic and tested under different greenhouse temperature regimes for attractiveness to olive fruit fly adults in cage tests. Adults tended to stay under the trap when temperatures were high because cooler conditions beneath the trap were more favorable. Addition of male attractants or bait sprays did greatly increase numbers of flies attracted to the traps, but high mortality of adults occurred when bait sprays were applied. The trap has potential as an attract-and-kill device for olive fruit fly. Compared with mating disruption, mass trapping for control of NOW has theoretical advantages and is compatible with organic production. Male abundance was therefore examined on 7 almond orchards of between 8 and 16 ha and between 0.4 and 16 km apart. NOW was abundant at all sites, but with some variation between sites. Distinct cohorts were apparent from data averaged from all sites, but less so in data from individual traps. These data provide a valuable baseline for a future experiment examining mass trapping for control of NOW. These activities address objective two. Studies to determine the effectiveness of high carbon dioxide/high temperature treatments control of diapausing codling moth larvae were begun. Treatment exposures of 8 hours to 98% carbon dioxide at 47 degrees C were effective in preventing test larvae from emerging as adults. Initial tests on the effect of the treatment on walnut quality were inconclusive. These activities address objective three.
1. Occurrence of the parasite Habrobracon hebetor in orchards and vineyards of central California. Habrobracon hebetor is a parasite commonly found attacking stored-product moth larvae. The presence of related moths such as navel orangeworm and raisin moth in orchards and vineyards suggests that H. hebetor might be found in these environments. ARS researchers at Parlier, California, sampled for the presence of H. hebetor in grape vineyards, almond orchards and pistachio orchards using traps baited with laboratory-raised moth larvae. Along with the parasites Venturia canescens and Mesostenus gracilis, Habrobracon hebetor was consistently recovered from all locations. This information will be used to evaluate the potential for the use of Habrobracon hebetor to reduce damage by navel orangeworm, a serious pest of California’s multi-billion dollar nut industry, thereby reducing the need for environmentally damaging pesticides.