Genetic improvement of host-seeking ability in the entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora toward the Red Palm Weevil Rhynchophorus ferrugineus

Publication date: Available online 11 May 2016 Source:Biological Control Author(s): Velayudhan Satheeja Santhi, Dana Ment, Liora Salame, Victoria Soroker, Itamar Glazer Rhynchophorus ferrugineus (red palm weevil) is highly susceptible to infection by the entomopathogenic nematodes Steinernema carpocapsae and Heterorhabditis bacteriophora. However, to reach and penetrate the insect in its habitat with good efficacy, the nematode infective juveniles (IJs) need to move through the tunnels bored by the feeding insect larvae in the tree trunk. We used a genetic-improvement approach to enhance host-seeking ability (HSA) of these nematode species’ IJs. The IJs were allowed to move through a 45-cm L-shaped tube toward red palm weevil larvae. The IJs which reached within 5 cm of the insect larvae were collected and reared. Selection cycles were repeated 15 times. The HSA of S. carpocapsae IJs was enhanced 11-fold (from 3.7 to 39.8% of all IJs reaching proximity of the larvae) and 8.5-fold (from 2.3 to 19.7%) for H. bacteriophora after 10 cycles of selection. Further selections (cycles 11 to 15) had no significant impact on improving HSA. HSA of the selected lines was highly specific to R. ferrugineus larvae. Selection for improved HSA also enhanced infectivity to R. ferrugineus, Galleria mellonella and Spodoptera littoralis. In addition, it enhanced host penetration 2.7-fold for S. carpocapsae and 1.5-fold for H. bacteriophora, and desiccation tolerance improved 1.2- ...

Source: Biological Control - May 11, 2016 Category: Biology Source Type: research