|Shapiro, David - CITRUS RESEARCH & EDUC.|
|Obrycki, John - IOWA STATE UNIVERSITY|
|Jackson, Jan - PIONEER HI-BRED INTERNTNL|
Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 5, 1999
Publication Date: N/A
Interpretive Summary: The black cutworm, a pest of corn, is usually managed with rescue treatments of chemical insecticides. Rescue treatments contribute to the chemical load in the environment and subsequently are detrimental to beneficial insects like ground beetles which feed on black cutworm larvae. Few alternatives to chemical insecticides are available to manage the cutworm. One alternative is a nematode that kills larvae of the black cutworm and is not harmful to the environment. Researchers investigated the effect of tillage on the efficacy of the nematode. They found reduced tillage (crop residue) led to increased efficacy of the nematode. The results of this research provide corn growers with an alternative to chemical insecticides that function well in reduced tillage systems. Use of these data will reduce the chemical load in the environment.
Technical Abstract: We determined the effects of crop residue on the persistence of Steinernema carpocapsae. During two consecutive years, nematodes (at 2.5 X 104 and 1.0 X 105 infective juveniles/m2) were applied to small field plots planted with corn. Nematode persistence was monitored by exposing Galleria mellonella larvae to soil samples from plots with and without crop residue (approximately 75% coverage of soybean stubble). Persistence of S. carpocapsae was significantly greater in crop residue plots than in plots without residue. In crop residue plots that received the higher rate of nematode application, larval mortality did not significantly decrease during the study period (3 to 5 days) and remained above 85%. In nematode- treated plots without crop residue, however, larval mortality fell from over 96% to below 11% and 35% in the first and second trials, respectively. The increased crop residue may have benefited nematode persistence through protection from desiccation or ultraviolet light. We conclude that increased ground cover in cropping systems (e.g., due to reduced tillage) may lead to increased insect pest suppression with entomopathogenic nematodes.