Methodology

Three hundred Petri dishes were lined with Whatman filter paper and the nematodes Steinernema karii, Heterorhabditis indica and Steinernema yirgalemense applied at the rate of 100 ij per dish (9 x 3.5) in fifty dishes for each nematode species and at 200ij/dish to another batch of fifty for each nematode species. The nematodes were applied in 1ml distilled water and given 30 minutes to distribute on the filter. The fifty Petri dishes treated with 100ij of S. karii per dish were subdivided into five groups of ten. The treatments (third instar G. mellonella and the 5th, 4th, 3rd and 2nd silk worm larval instars) were applied in ten replicates first to Petri dishes treated with 100 ij of S. karii and then to the 200 ij of S. karii dose. The procedure was repeated for H. indica and S. yirgalemense and the experiment laid out in a completely randomised design. The treatments were left on laboratory benches at room temperature (18-25°C) and 60% relative humidity for three days. The cadavers from each treatment were placed in own White traps (Woodring & Kaya, 1988) for extraction of emerging entomopathogenic nematodes. Nematodes were harvested for seven days and cleaned by sedimentation and decantation. Nematodes from each treatment were counted under a binocular microscope. The mortality data was subjected to Chi-square analysis while nematode yield data was analysed for variance. Significantly different treatment means were separated using the Student Neuman Keus (SNK).

African Dryland Institute for Sustainability , University of Nairobi