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ARS Home » Pacific West Area » Wapato, Washington » Temperate Tree Fruit and Vegetable Research » Research » Publications at this Location » Publication #223025
Title: SEMI-FIELD EVALUATION OF THE POTATO TUBER MOTH, PHTHORIMAEA OPERCULELLA ZELLER, GRANULOVIRUS AND BACILLUS THURINGIENSIS VAR. KURSTAKI FOR SEASON-LONG CONTROL OF P. OPERCULELLA

Author
item Arthurs, Steven
item Lacey, Lawrence
item PRUNEDA, JONATHAN - WSU, PULLMAN, WA
item RONDON, SILVIA - HERMISTON AG&EXT CTR, OR

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/7/2008
Publication Date: 11/12/2008
Citation: Arthurs, S.P., Lacey, L.A., Pruneda, J.N., Rondon, S. 2008. Semi-field evaluation of the potato tuber moth, phthorimaea operculella zeller, granulovirus and bacillus thuringiensis var. kurstaki for season-long control of p. operculella. Entomologia Experimentalis et Applicata 129:276-285.

Interpretive Summary: The potato tuber moth (PTM) is an invasive species of the Pacific Northwest of the United States that has recently caused damage to potato field crops and also tubers in storage facilities. Currently, there are few insecticides for PTM control late in the potato growing season, often the time PTM control is most needed. One possible solution is the use of low risk biological pesticides that have fewer restrictions on their use. Scientists at the USDA-ARS Yakima Agricultural Research Laboratory in Washington have evaluated an insect-specific virus (PoGV) and a bacterium Bacillus thuringiensis var. kurstaki (Btk), for PTM control. Results of field experiments in 2006 and 2007 showed that both PoGV and Btk may be used as biological insecticides, although PoGV was the more effective of the two and controlled up to 97% of moths on potato foliage in one season. Both PoGV and Btk provide alternatives to control PTM very late in the growing season thus reducing the risk of tuber damage in storage. Exposure of pesticide applicators, the food supply and beneficial insects to harmful chemical pesticides can be eliminated through the use of these agents.

Technical Abstract: In 2006 and 2007, scientists at YARL evaluated two low risk biological pesticides, an insect-specific virus (PoGV) and a bacterium [Bacillus thuringiensis var. kurstaki (Btk)], that would provide alternative tools to control PTM. Compared with controls, 10 weekly applications of PoGV (standard rate) reduced PTM in field cages by 86-96% on foliage and 90-97% on tubers added to cages shortly before harvest. Between 82 - 95% of larvae became infected with the virus. However, reducing the rate PoGV (1/10th rate or ½ application frequency) made the insecticidal program less effective. Equivalently timed treatments with Btk (1.12 kg product/ha) were less effective than PoGV (standard rate), causing a 36-76% reduction in larvae recovered on tubers. A PoGV/Btk alternation was more effective than Btk alone and as effective as PoGV in 2007 but not in 2006. The residual activities of insecticide deposits on potato foliage were also evaluated. Fresh residues were highly effective (= 93 % mortality) but showed a steady decline in their ability to kill tuber moth larvae over the next 10-14 days. Both PoGV and Btk provide alternatives to control PTM close to and even following potato harvest, thus reducing the risk of tuber damage in storage.