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United States Department of Agriculture

Agricultural Research Service

Title: Impact of Host Cadaver on Survival and Infectivity of Entomopathogenic Nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) under Desiccating Conditions

Authors
item Perez, Enrique - VPI, VIRGINIA
item Lewis, Edwin - VPI, VIRGINIA
item Shapiro Ilan, David

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 6, 2002
Publication Date: February 1, 2003
Citation: PEREZ, E.E., LEWIS, E.E., SHAPIRO ILAN, D.I. IMPACT OF HOST CADAVER ON SURVIVAL AND INFECTIVITY OF ENTOMOPATHOGENIC NEMATODES (RHABDITIDA: STEINERNEMATIDAE AND HETERORHABDITIDAE) UNDER DESICCATING CONDITIONS. JOURNAL OF INVERTEBRATE PATHOLOGY. 2003. v.82. p.111-118.

Interpretive Summary: Insect-killing nematodes are small round worms that kill insect pests but don't harm people or the environment. There are two methods of applying the nematodes. The nematodes are usually applied mixed with water. However, they may also be applied in nematode-infected insects, which are distributed in the area where pest suppression is required; the nematodes then emerge from the dead infected-insects and go on to attack other insect pests. We compared the two application methods to see which might be better under dry conditions. We tested three different kinds (species) of nematodes. We found that two of the three species survived better when applied in infected-insects compared to a water application (no difference was observed in the third species). This research confirms previous studies reporting various benefits of applying insect-killing nematodes in infected insects.

Technical Abstract: Entomopathogenic nematode species of Steinernema carpocapsae, S. riobrave, or H. bacteriophora were used to compare survival and infectivity among infective juveniles (IJs) emerging from cadavers into sand (treatment c), IJs applied to sand in aqueous suspensions after collection from a White trap (treatment a), and IJs that crawled into sand from a suspended mesh (treatment m). Nematode survival infectivity was recorded in sand at three-day intervals during 21 days of storage in desiccators at 75% relative humidity and 25 degrees C. Infectivity was measured by exposing 5 Galleria mellonella for 16 h to IJs. Treatment did not affect percent survival of H. bacteriophora IJs. Percent survival of S. riobrave and S. carpocapsae IJs was lowest from treatment a. Across all treatments, by 10 days after the beginning of the experiments, IJ survival declines to 93%, 43% and 28% of levels on day 1 for H. bacteriophora, S. riobrave, and S. carpocapsae respectively. For the three treatments, infection rate over time was described by a negative exponential function for S. riobrave and S. carpocapsae and by a sigmoid function for H. bacteriophora.

Last Modified: 7/28/2014