Evaluation of native entomopathogenic nematodes for the control of the European cherry fruit fly Rhagoletis cerasi L. (Diptera: Tephritidae) larvae in soil

Authors: İLKER KEPENEKCİ, SELÇUK HAZIR, AYŞE ÖZDEM

Abstract: Turkey is the world's largest producer of sweet cherries. The European cherry fruit fly, Rhagoletis cerasi L. (Diptera: Tephritidae), is a major pest of sweet cherry crops in Europe and Turkey. The detection of only one larva in the fruit by the processor can result in the rejection of the entire crop of that orchard and/or farm as \"wormy\" and unmarketable. The main control tactic for R. cerasi is to prevent the females from laying eggs in the fruit. Currently, only a few insecticides are being used, and their application is debatable due to problems with residual ecotoxicity for humans and beneficial organisms. As an alternative to using insecticides for the reduction of adult populations, 4 indigenous entomopathogenic nematode species, Steinernema carpocapsae (Anamur isolate), S. feltiae (Rize isolate), Heterorhabditis bacteriophora (Ekecik isolate), and H. marelatus (Ankara isolate), were bioassayed against last-instar R. cerasi larvae at different temperatures (10, 15, and 25 °C) and nematode concentrations (0, 100, 500, and 1000 IJs/larva). Temperature and nematode concentration had a significant effect on the efficacy of nematode species. S. feltiae was the most virulent species at all temperatures and nematode concentrations. Only S. feltiae showed higher than 40% mortality at low temperatures (10 and 15 °C). At 25 °C, S. feltiae caused 95% mortality, followed by H. marelatus (82%) and H. bacteriophora (76%), at 1000 IJs/larva concentration. Our results indicate that R. cerasi larvae are highly susceptible to entomopathogenic nematode infection. In particular, S. feltiae has high potential for reducing last-instar larval populations, thus decreasing the adult population in the spring.

Keywords: Entomopathogenic nematodes, Steinernema, Heterorhabditis, Rhagoletis cerasi, biological control

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