Potential of entomopathogenic nematodes of the genus Heterorhabditis for the control of Stomoxys calcitrans (Diptera: Muscidae)

Abstract The present study verified the pathogenic potential of entomopathogenic nematodes (EPNs) of the genus Heterorhabditis (Heterorhabditis bacteriophora, isolate HP88 and Heterorhabditis baujardi isolate LPP7) to immature stages of Stomoxys calcitrans in the laboratory. All EPN concentrations of the H. bacteriophora HP88 strain caused mean larval mortality greater than 90% after four days. Higher concentrations of the H. baujardi LPP7 isolate (≥50 EPNs/larva) eliminated more than 70% of larvae after six days with the concentration 200 EPNs/larva reaching mortality levels of 93.3%. The larval mortality at all concentrations of EPNs (25, 50, 100, 150, and 200 EPNs/larva) for both strains was significant (p<0.05) when compared to the respective control groups. Concentrations of H. bacteriophora HP88 yielded an LC50 of 0.36 EPN/larva and LC90 of 29.1; while H. baujardi LPP7 yielded an LC50 of 39.85 and LC90 of 239.18. H. bacteriophora HP88 provided greater inhibition of the emergence of adults when compared to the response obtained with H. baujardi LPP7. EPNs did not cause considerable mortality when applied directly to pupae. The set of observed results suggests that the EPNs of the genus Heterorhabditis, isolates HP88 and LPP7, are a promising alternative in the control of the stable fly.

摘要 本研究在室内条件下验证了异小杆属（Heterorhabditis）昆虫病原线虫（entomopathogenic nematodes，EPNs）对厩螫蝇（Stomoxys calcitrans）未成熟虫态的致病潜能，供试菌株包括嗜菌异小杆线虫（Heterorhabditis bacteriophora）HP88分离株与鲍氏异小杆线虫（Heterorhabditis baujardi）LPP7分离株。培养4天后，嗜菌异小杆线虫HP88菌株的所有供试浓度均使幼虫平均死亡率超过90%。鲍氏异小杆线虫LPP7分离株的高浓度组（≥50条线虫/幼虫）在6天后可杀灭70%以上的幼虫，其中200条线虫/幼虫浓度组的幼虫死亡率达93.3%。与各自对应的对照组相比，两个菌株的所有供试线虫浓度（25、50、100、150及200条/幼虫）处理组的幼虫死亡率均显著高于对照组（p<0.05）。嗜菌异小杆线虫HP88的半致死浓度（LC50）为0.36条/幼虫，90%致死浓度（LC90）为29.1；鲍氏异小杆线虫LPP7的LC50为39.85，LC90为239.18。相较于鲍氏异小杆线虫LPP7，嗜菌异小杆线虫HP88对厩螫蝇成虫羽化的抑制效果更为显著。直接将昆虫病原线虫施用于蛹时，未造成显著的蛹死亡。本研究所有观测结果表明，异小杆属HP88与LPP7分离株昆虫病原线虫是防控厩螫蝇的潜在有效生防手段。