Location: Horticultural Crops Research2012 Annual Report
1a. Objectives (from AD-416):
Objective 1: Employ semiochemicals to enhance the monitoring and management of Otiorhynchus sulcatus and Drosophila suzukii as well as to manipulate their natural enemies. Objective 2: Develop integrated pest management tools for key pests of ornamental nursery and small fruit crops. Objective 3: Address invasive and reemerging arthropod pests of nursery and small fruit crops.
1b. Approach (from AD-416):
The bionomics and the chemical ecology of economically-important insect pests of nursery and small fruits crops will be studied in the field and under controlled conditions of temperature, humidity, and light in growth chambers and greenhouses. Emphasis will also be placed on understanding the ecology of the microbial control agents of these pests in the laboratory greenhouse and field. Together, the information compiled on the ecology of the pests and their respective microbial control agents will be integrated to begin development of biologically-based pest management programs.
3. Progress Report:
To determine the efficacy of methyl salicylate (MeSA), an herbivore-induced plant volatile, for enhancing biological control, we exposed lady beetle and ground beetle predators to MeSA in field cages and monitored predation. The presence/absence of MeSA did not appear to affect the predators' consumption rate or search efficiency. This response enables us to predict the impact of this alternative control strategy beyond counting the number of predators in a treated area. To clarify the role of raspberry aphids in vectoring viruses to raspberries, we monitored aphid feeding patterns on susceptible and resistant raspberry plants, their developmental times under a range of controlled temperatures and outdoors, and population trends in raspberry fields. These observations will enable growers to improve timing of treatments for aphids to reduce virus spread. To better understand the new invasive spotted wing drosophila, we conducted studies on the susceptibility of different ripeness stages and cultivars of blueberries, ornamental hosts, their spring time activity, and the efficacy of the predatory rove beetle. These results have been used to develop revised management guidelines in 2012. To determine the rhizosphere competence of the commercial isolate of Metarhizium anisopliae, inoculated cuttings in fungal treated and control soils were planted. Plants were then evaluated for rhizosphere colonization and the efficacy of treated roots in protecting the plants against feeding by Otiorhynchus sulcatus larvae. The rhizosphere of a wide variety of ornamentals are colonized with the insect killing fungus and the presence of the fungus significantly reduces O. sulcatus damage. To enhance the trapping efficiency of a novel trap developed in 2011, we combined the trap with attractive semiochemicals for capturing O. sulcatus adults. Replicated field studies were performed in Prunus rootstock infested with O. sulcatus in 2012. We were able to enhance trap captures with the addition of the attractive semiochemical. Field studies were performed to test novel insecticide application strategies for protecting blueberries and raspberries from spotted wing drosophila. Application strategies evaluated in blueberries and raspberries are border and alternative row sprays respectively. Preliminary data look promising, but further studies over time and at additional locations are required before recommendations for grower adoption can be made.
1. Improved trapping for spotted wing drosophila. The spotted wing drosophila is a recent invasive pest of small and stone fruits in the United States, Canada, Mexico, and Europe. In a coordinated study comparing six popular trap designs across seven states/provinces in North America and nine crop types, ARS scientists in Corvallis, Oregon, determined that traps with greater entry areas caught more flies than traps with smaller entry areas. These results provided immediate comparisons for growers/scouts who wanted to improve their 2012 trapping protocol as well as insight on other physical features to examine for future trap improvement. Monitoring programs in Washington and Canada have been adjusted in 2012 based on these results.
2. Aphid resistance in red raspberry. Pest and virus control in raspberries can be achieved with aphid resistant plants, but the mechanism of resistance is unknown. ARS scientists in Corvallis, Oregon, found that raspberry aphids ingested less phloem sap on resistant plants than on susceptible plants, suggesting that the mechanism for resistance is located in the phloem. These findings may explain why aphid-transmitted viruses in resistant cultivars are uncommon due to inefficient virus acquisiton and will facilitate breeding of future cultivars.
3. Quantifying Otiorhyncus sulcatus larval damage to cranberries. O. sulcatus is a serious pest of cranberry throughout the United States. We correlated damage caused by feeding larvae to known O. sulcatus egg densities. Damage increased with increasing egg density, and more damage was found in the variety ‘Stevens’ than ‘McFarlin’. Our results indicate that increased BVW egg density has a negative effect on cranberry plant health. The severity of this effect depends on variety and seasonal conditions.Woods, J., James, D., Lee, J.C., Gent, D.H. 2011. Evaluation of airborne methyl salicylate for improved conservation biological control of two-spotted spider mites and hop aphid in Oregon hop yards. Experimental and Applied Acarology. 55:401-416.