Submitted to: Journal of Entomological Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/1/2005
Publication Date: 4/1/2006
Citation: Lacey, L.A., Granatstein, D., Arthurs, S.P., Headrick, H.L., Fritts, R. 2006. Use of entomopathogenic nematodes (Steinernematidae) in conjuction with mulches for control of overwintering codling moth (Lepidoptera: Tortricidae). J. Entomol. Sci. 41(2): 107-119. Interpretive Summary: Codling moth is the principal pest of apple and pear in the Pacific Northwest of the United States. The successful control of overwintering codling moth larvae would result in substantial reduction in fruit damage in the subsequent growing season. Insect-specific nematodes can target overwintering larvae in their cryptic habitats when conditions are favorable for infectivity. Compared with bare ground, mulches may enhance control by nematodes by providing hibernacula for larvae that facilitates ease of treatment and that maintain moisture. Researchers at the USDA-ARS, Yakima Agricultural Research Laboratory are conducting studies to develop and evaluate the combined effects of insect-specific nematodes and mulch for control of cocooned larvae in orchards. It was found that infective stages of two species of nematodes were highly effective at controlling cocooned larvae. Mulch provided additional moisture and improved activity of the nematodes. These findings indicate that insect-specific nematodes could provide a non-chemical means of control that could be applied in the fall and spring when all of the codling moth population is overwintering in mulch.
Technical Abstract: Two insect-specific nematodes, Steinernema carpocapsae and S. feltiae were applied at a rate of 2.5 billion infective juveniles (IJs)/ha against cocooned sentinel codling moth larvae with 2 hours of post application irrigation in plots that were covered with one of four mulches (clover, shredded paper, hay or wood chips) or to bare plots on September 29, 2003. Average mortalities of 97 and 98%, respectively, in paper-mulched plots treated with S. carpocapsae or S. feltiae IJs was observed compared to 80 and 76% mortality, respectively, in bare plots. Larvicidal activity for S. feltiae against sentinel larvae that were placed in crevices in the soil was nearly identical in all mulched and bare plots (97-100% mortality), but reduced for S. carpocapsae in wood chip and clover plots (76-79% mortality) relative to paper, hay and bare plots (93-97% mortality). Applications of S. carpocapsae and S. feltiae at a reduced rate of one billion IJs/ha on April 20, 2004, with 1 hour of post application irrigation resulted in 13.1 and 7.4% reduction in sentinel larvae in bare plots compared to 36 and 62% in mulched plots, respectively. Applications of S. carpocapsae and S. feltiae at a rate of 2.5 billion IJs/ha on September 2, 2004 to bare and wood chip mulched plots with 1 hour of post application irrigation resulted in 21 and 65% reduction in sentinel larvae in bare plots compared to 93 and 85% in mulched plots, respectively.