SUSCEPTIBILITY OF THE COLORADO POTATO BEETLE AND THE SUGARBEET WIREWORM TO STEINERNEMA-FELTIAE AND STEINERNEMA-GLASERI

  • 1 January 1983
    • journal article
    • research article
    • Vol. 15  (4) , 597-601
Abstract
In laboratory tests, larvae of the Colorado potato beetle (CPB), L. decemlineata (Say) and the sugarbeet wireworm (SBW), L. californicus (Mannerheim), were exposed to the nematodes S. feltiae Filipjev (Mexican strain) (= Neoaplectana carpocapsae) and S. glaseri Steiner in soil. S. feltiae caused significantly higher mortality in SBW larvae than did S. glaseri, but both nematode species were equally effective against CPB larvae. The minimum concentration of S. feltiae for 100% mortality of CPB larvae after 13 days was 157 nematodes/cm2 of soil, and the LC50 based on 6-day mortality was 47.5 nematodes/cm2; in contrast, 100% mortality of SBW larvae was not achieved with even the highest concentration tested, 393 nematodes/cm2. CPB adults emerging from nematode-contaminated soil were not infected. In field cage tests, S. feltiae applied to the soil surface at the rates of 155 and 310 nematodes/cm2 soil caused 59% and 71% mortality, respectively, of late-4th-instar spring-generation CPB, and 28% and 29% mortality, respectively, of SBW. No infection was obtained when larvae of summer generation CPB and SBW were placed in the same cages approximately 6 wk after nematodes were applied to the soil. Inundative soil applications of S. feltiae, though cost prohibitive at present, were effective in reducing caged CPB and SBW field populations.