Comparative susceptibility of Macrotermes bellicosus and Trinervitermes occidentalis (Isoptera: Termitidae) to entomopathogenic nematodes from Benin

Abstract

The differential susceptibility of two termite species, Macrotermes bellicosus and Trinervitermes occidentalis, to four entomopathogenic nematodes (EPN) isolates from Benin, Heterorhabditis indica Ayogbe1, H. sonorensis Azohoue2, H. sonorensis Ze3 and Steinernema sp. Bembereke, was bio-assayed in laboratory tests. Soldiers of both M. bellicosus and T. occidentalis were similarly susceptible, but more susceptible than workers. Forty-eight h post-exposure of workers of M. bellicosus to 50 infective juveniles (IJ) of H. indica Ayogbe1, H. sonorensis Azohoue2, H. sonorensis Ze3 and Steinernema sp. Bembereke for each termite resulted in 96.3, 87.9, 94.5 and 75.0% mortality, respectively, whereas under the same conditions, these EPN isolates caused 91.7, 98.5, 75.0 and 95.0% mortality of workers of T. occidentalis. Soldiers of M. bellicosus were the most invaded with 13.2-18.6% of applied IJ. Based on concentration-mortality data, the isolates H. indica Ayogbe1 and H. sonorensis Ze3 were more virulent to M. bellicosus with LC50 values of 11 IJ, whereas Steinernema sp. Bembereke was the most virulent to T. occidentalis with LC50 values of 12 IJ. However, none of these isolates showed the highest penetration rate. All tested EPN isolates can recycle in both M. bellicosus and T. occidentalis. Our EPN repellent-dispersing assay did not show evidence that M. bellicosus and T. occidentalis would be able to detect the presence of IJ of any EPN isolates/species. However, it was observed that nematode dispersal occurred by infected termites or phoresis.