Laboratory and field evaluations of an entomogenous nematode (Nemataoda: Steinernematidae) for German cockroach (Dictyoptera: Blattellidae) control
1993
Appel, A.G. | Benson, E.P. | Ellenberger, J.M. | Manweiler, S.A.
Pads impregnated with the nematode Steinernema carpocapsae (Weiser) and enclosed in a moisture-retaining station were evaluated in field and laboratory experiments with the German cockroach, Blattella germanica (L.). In continuous exposure tests without harborage, LT50s ranged from 2.06 to 12.64 d for 0.5 X 10(6) nematodes and 10(6) nematodes, respectively. LT50s estimated with Ebeling choice boxes were 2.5 to 8.4 times greater than those from the continuous exposure tests. Relative repellency, measured as the mean percentage of live cockroaches in the light side of the choice box, was greatest for stations with 0.5 X 10(6) nematodes (6.65%) and least (3.70%) for stations containing 2 X 10(6) nematodes. Movement by cockroaches confined to nematode deposits declined linearly with increasing nematode density. The number of antennal preens by confined cockroaches increased curvilinearly with nematode density. A performance index that combined choice-box repellency and mortality data indicated that stations containing 2 X 10(6) nematodes had the greatest potential for field effectiveness. Stations containing 2 X 10(6) nematodes significantly reduced German cockroach trap catch in infested apartments.
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