1a. Objectives (from AD-416)
The overall objective is to develop practical and economical non-chemical insect control and disinfestation treatments that are safe and environmentally acceptable to replace methyl bromide for fresh and durable commodities. Objective 1: Develop a biologically-based management program using biological agents and cultural controls. • Sub-objective 1.A. Develop a biological control program for olive fruit fly using imported parasitoids • Sub-objective 1.B. Develop cultural control methods for olive fruit fly • Sub-objective 1.C. Develop a laboratory diet for olive fruit fly • Sub-objective 1.D. Improve control of navel orangeworm in orchards by using entomopathogenic nematodes that target over-wintering larvae • Sub-objective 1.E. Develop information for obtaining approval to release insect parasitoids into bulk-stored dried fruits and nuts. • Sub-objective 1.F. Determine the potential of commercially available or novel pathogens to control stored product Coleoptera. Objective 2: Develop a sex pheromone based program for use in the integrated management of navel orangeworm. • Sub-objective 2.A. Develop a stable formulation for the recently identified female sex pheromone • Sub-objective 2.B. Develop trapping data to calculate realistic navel orangeworm numbers based on standard sticky trap catch data. • Sub-objective 2.C. Determine the size of mating disruption treatment block necessary for reduction of navel orangeworm damage in almonds • Sub-objective 2.D. Determine fitness of females and potential impact of mating disruption at times of first and second flight. Objective 3: Develop alternative physical treatments for dried fruits, nuts, and fresh fruits • Sub-objective 3.A. Determine whether forced hot air combined with controlled atmospheres (CATTS) for stone fruit or forced hot air for oranges are viable quarantine treatments. • Sub-objective 3.B. Develop and field test low and high temperature treatments for dried fruit and nut insect pests. • Sub-objective 3.C. Develop and field test vacuum treatments using low cost, flexible storage containers for dried fruit and nut insect pests.
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), 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. In addition, with the elimination of methyl bromide as a fumigant because of its ozone depletion, the development of alternatives is an immediate concern. 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 will include the development of biological and cultural control practices for olive fruit fly, improved field control of navel orangeworm with mating disruption and entomopathogenic nematodes, improved sex pheromone of navel orangeworm, new microbial controls for stored product beetles, commercial-scale forced hot air control atmosphere treatment for stone fruits, volatile markers to identify suitable hot forced air treatments for citrus, and radio frequency heating, low temperature storage, vacuum treatments, and parasitoid releases for control of postharvest dried fruit and nut insects. New, non-chemical methods for control of these economically important pests will be the outcome of this research. Formerly 5302-43000-031-00D (03/08).
3. Progress Report
A braconid parasitoid was reared on sterile Medfly larvae in Guatemala and released for biological control of olive fruit fly in California olives. Parasitoids were recovered from olive fruit fly pupae in most locations with a reduction in pest numbers in Lodi. The parasitoid showed high dispersal capacity with continuous flight for up to 110 minutes in lab tests. Irradiation of the Medfly host at different doses in Guatemala did not affect parasitoid survival after shipment but life span was increased with water, food, and cool temperatures. Research was conducted on the population density of navel orangeworm in pistachio orchards undergoing varying levels of sanitation to establish causal relationships between the level of unharvested pistachios, navel orangeworm population density, and pistachio damage. Studies were done in almonds to determine if the use of entomopathogenic nematodes for navel orangeworm control in almonds is economical in this system. Collection and analysis procedures of pheromone compounds from natural and synthetic sources were refined for use in developing a field lure for the navel orangeworm. New handling procedures reduce decomposition of labile compounds and formulation matrices were cleaned and treated with stabilizers. Sex pheromone components from individual moths can now be analyzed and low release rates of synthetic pheromones can be assessed. Field trapping of navel orangeworm in female-baited traps show that saturation effects appear logarithmic as more males are trapped. Significant progress was made in determining dispersal capacity of gravid navel orangeworm females, necessary in determining the minimum size of a mating disruption block for this species. Peaches infested with oriental fruit moth larvae and packed into boxes stacked onto a commercial pallet were treated with forced hot air combined with a controlled atmosphere. Complete insect mortality was obtained by heating the interior of the fruit to 43.5°C and holding at that temperature for 45 minutes. A total of 6391 larvae were killed. Fruit quality was unaltered by the treatment in three of the four varieties tested, while there was a 15% decline in marketable fruit in one of the varieties. The cowpea weevil life stage most tolerant to radio frequency heat treatments was identified as the pupal stage, confirming the results of previous studies done with heat blocks. The effect of age and relative humidity on the response of three species of moth eggs to vacuum treatments was determined. The above research addresses National Program objectives by reducing postharvest use of methyl bromide for perishable and durable commodities, and protecting postharvest commodities from pests through ecologically sound means.
1. Biological and Cultural Control of Olive Fruit Fly. Olive fruit fly is the key pest of canning olives and threatens new oil olive plantings in California. ARS scientists at Parlier, CA sustained a biological control program to reduce pest numbers by releasing a parasitoid imported from infested olive groves in Guatemala. Irradiating the Medfly host in Guatemala to produce large numbers of the parasitoids did not affect parasitoid fitness. The procedure allows the importation of large numbers of the beneficial insect while minimizing the risk of introducing fertile hosts. The work helps protect the California canned olive and oil industry, valued at $75 million annually, while reducing the need for environmentally damaging pesticides.
2. Quantifying Overwintering Survival of Navel Orangeworm in Butte and Padre Almonds. Navel orangeworm is the primary pest of California almonds and pistachios. ARS scientists at Parlier, CA, assessed the overwintering survival of this insect in 5 varieties of almonds. These data will be used to determine if certain varieties are at greater risk of harboring overwintering populations. This information allows management of certain varieties as targeted for more stringent control, which in turn will reduce insect damage and production costs.
3. Efficacy of Mating Disruption for Navel Orangeworm in Almonds. A previous study found that mating disruption significantly reduced damage by navel orangeworm. ARS scientists in Parlier, CA, in collaboration with the University of California and private industry, performed a follow-up study at a site in a different region with higher navel orangeworm abundance and different almond varieties. A significant reduction of navel orangeworm fertility and damage was demonstrated. These findings will accelerate the adoption of mating disruption for navel orangeworm, thereby protecting California’s >$2 billion dollar almond industry while reducing insecticide use.
4. Testing of Forced Hot Air Combined with Controlled Atmospheres as an Effective Means of Insect Disinfestation. Heat combined with controlled atmospheres is an effective means to kill insects but the practicality of applying this technology to peaches and nectarines in stacked boxes is unknown. ARS researchers from Parlier, CA and Wapato, WA evaluated this treatment. It was found that a combination treatment of forced air heat and controlled atmospheres applied to commercial pallets of peaches infested with oriental fruit moth resulted in 100% mortality of this insect pest. This work showed the potential commercial feasibility of a non-chemical means of quarantine treatment for peaches and nectarines which would reduce the need for environmentally damaging fumigants.
5. Effect of Age and Relative Humidity on Response of Moth Eggs to Low Pressure Treatments. Low pressure treatments are potential alternatives to environmentally damaging chemical fumigants for disinfesting California walnuts of insect pests, but information about the effects of various environmental parameters on treatment efficacy is needed. ARS researchers at Parlier, CA conducted studies on the effects of age and relative humidity on the response of insect eggs to low pressures. It was discovered that, unlike larval stages, eggs are relatively unaffected by differences in relative humidity, and that young eggs were often more tolerant than older eggs. This information will be used to develop effective treatment schedules that will allow processors to disinfest postharvest products while reducing the need for pesticides that damage the ozone layer or contribute to global warming.
Burks, C.S., Higbee, B.S., Kuenen, L.P., Brandl, D.G. 2009. Monitoring Amyelois transitella Males and Females with Phenyl Propionate Traps in Almonds and Pistachios. Entomologia Experimentalis et Applicata. 133(3):283-291.