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Submitted to: Southeastern Peach Convention Proceedings
Publication Type: Proceedings Publication Acceptance Date: 1/8/2006 Publication Date: 1/8/2006 Citation: Cottrell, T.E., Shapiro Ilan, D.I. 2006. Management strategies for borers. In: Proceedings of the Southeastern Peach Convention, January 5-8, 2006, Savannah, Georgia. p. 17. Interpretive Summary: The peachtree borer (Synanthedon exitiosa) and lesser peachtree borer (Synanthedon pictipes) cause serious damage to peach trees when larvae tunnel under the bark. Typical control tactics against the two pest species involves application of chemical insecticides. This approach is very effective against the single generation of the peachtree borer but not feasible against the multiple generations of the lesser peachtree borer, especially when fruit is on the tree. Thus we investigated a biological means, insect-killing nematodes, for managing these two pests. In both a field trial and a laboratory assay, the nematode Steinernema carpocapsae (All strain) was significantly more effective against peachtree borer larvae than Steinernema riobrave. In fact, 88% control of peachtree borer larvae was obtained from a single application in a field trial using S. carpocapsae. We also found that the lesser peachtree borer is highly susceptible to entomopathogenic nematodes. We determined the susceptibility of LPTB larvae to six entomopathogenic nematode species: Heterorhabditis bacteriophora, Heterorhabditis indica, Heterorhabditis marelatus, Steinernema carpocapsae, Steinernema feltiae and Steinernema riobrave. Against the lesser peachtree borer, nematodes in the genus Steinernema were more virulent than those in the genus Heterorhabditis. The virulence of S. carpocapsae was greater than S. riobrave with S. feltiae being intermediate between the two, and no difference in virulence was detected among the heterorhabditids. Technical Abstract: The peachtree borer (Synanthedon exitiosa) and lesser peachtree borer (Synanthedon pictipes) are native insects that cause serious damage to peach trees in the southeastern U.S. Damage by both species is exacted on trees through larvae feeding on the cambium. Management of the univoltine peachtree borer is done using a broad-spectrum insecticide but the multivoltine lesser peachtree borer presents a challenge for insecticidal control when fruit are on the tree. Entomopathogenic nematodes may provide an alternative to chemical control thus we investigated susceptibility of the peachtree borer and lesser peachtree borer to entomopathogenic nematodes. In both a field trial and a laboratory assay, the nematode Steinernema carpocapsae (All strain) was significantly more effective against peachtree borer larvae than Steinernema riobrave. In fact, 88% control of peachtree borer larvae was obtained from a single application in a field trial using S. carpocapsae. We also found that the lesser peachtree borer is highly susceptible to entomopathogenic nematodes. We determined the susceptibility of LPTB larvae to six entomopathogenic nematode species: Heterorhabditis bacteriophora, Heterorhabditis indica, Heterorhabditis marelatus, Steinernema carpocapsae, Steinernema feltiae and Steinernema riobrave. Against the lesser peachtree borer, the steinernematids were more virulent than the heterorhabditids, the virulence of S. carpocapsae was greater than S. riobrave with S. feltiae being intermediate between the two, and no difference in virulence was detected among the heterorhabditids. A comparison of nematode virulence in S. pictipes to virulence in two hosts known to be highly susceptible to nematodes (i.e., the wax worm [Galleria mellonella (L.)] and meal worm [Tenebrio molitor (L.)], indicated a high level of susceptibility in S. pictipes as well. |
