Evaluation of Entomopathooentc Nematodes on the Beet Cyst Nematode Heterodera Schachtii

Abstract

I(evwor&: Steinernema carpocapsae, beet cyst nematode, sugar beetThe inundative application of Steinernema carpocapsae (DDl36) was shown to increase populations of rhabditid nematodes and decrease plant-parasitic genera in soil (7). The invasion of tomato roots by the root-knot nematode Meloidogyne javanica was markedly decreased by application of S. glaseri (1) and by S. carpocapsae, S. feltiae and S. riobravis (6). The present paper reports on the effect of S. feltiae and Heterorhabditis bacteriophora on the beet cyst nematode, Heterodera schuchtii. and Methods Sugar beet seedlings (Beta vulgaris L.) cv. Dora, transplanted into 8 cm plastic pots (one seedlindpot) containing a sand mixture, were watered daily with Hoagland's nutrient solution and maintained under glasshouse conditions. The entomopathogenic nematodes used were Steinernemafeltiae (UK isolate from Reading University) and a Heterorhabditis bacteriophora isolate from Spain. Both entomopathogenic nematode species were cultured by infecting last instar Galleria mellonella (greater wax moth) with infective juveniles of each species: after 9-10 days the newly produced infective juveniles were harvested from the dead G. mellonella larvae on modified White traps (3). When sugar beet seedlings were 20 cm in height, infective juveniles of both entomopathogenic nematode species were applied daily at a rate of 10 000 per pot over a 10 day period. On the third day after the initial application of the entomopathogenic nematodes, either 1000 or 2000 freshly hatched second stage juveniles of the sugar beet cyst nematode were added per pot. Ten replicates were used in each treatment. The plants were grown on for two months in a glasshouse (photoperiod 15/9 lighudark at a temperature ranging from 25-30°C) when the final populations of the sugar beet cyst nematode were determined by extracting the cysts with the Fenwik can (4). The cysts were separated from the debris by alcohol flotation (7) and were crushed in water in a cyst homogeniser (Eijkelkamp Agrisearch Equipment, Netherlands). Data from the experiment were analysed by ANOVA and the Duncan multiple-range test. IlGsuk2The total number of H. schuchtii eggs was significantly (P = 0.01) decreased by the presence of both entomopathogenic nematode species. Steinernemafeltiae was the most effective entomopathogenic nematode at both levels of H. schachtii inoculum.-100 -