Skip to main content
ARS Home » Pacific West Area » Wapato, Washington » Temperate Tree Fruit and Vegetable Research » Research » Publications at this Location » Publication #226235
Title: Animal Manure Harms Entomopathogenic Nematodes

Author
item RAMIREZ II, RICARDO - WASHINGTON STATE UNIV
item HENDERSON, DONNA - WASHINGTON STATE UNIV
item RIGA, KATARINA - WASHINGTON STATE UNIV
item CARPENTER-BOGGS, LYNNE - WASHINGTON STATE UNIV
item Lacey, Lawrence
item SNYDER, WILLIAM - WASHINGTON STATE UNIV

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2009
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Colorado potato beetle (CPB) is a significant pest of potato in the potato production areas of Washington, Oregon and Idaho and other regions in North America where potato is grown. The traditional means of fertilizing potato crops is with chemical fertilizers. Organic growers have investigated the use of animal manure as a fertilizer. Organic growers are also investigating insect–specific nematodes for control of CPB. Researchers at Washington State University in Pullman and Prosser, WA and at the USDA-ARS Research Laboratory in Wapato, WA are investigating the compatibility of these two methods for potato protection and production. Most species of insect-specific nematodes are negatively affected by animal manure. Alternative methods of fertilizing should be used when the insect-specific nematodes are employed for control of CPB. Nematodes and other microbial control agents provide alternatives to conventional chemical pesticides and will play significant roles in sustainable agriculture and safer food.

Technical Abstract: Animal manure forms an alternative to synthetic fertilizer that provides the additional benefits of reducing nutrient leaching and soil erosion, and promoting greater soil biodiversity. Studies show that animal manures can suppress plant parasitic nematodes by increasing densities of antagonistic microbial species or increasing concentrations of anhydrous ammonia. However, animal manure adds organic matter to the soil, providing additional resources for free-living nematode populations. With these opposing effects on nematodes, it is unclear how animal manure impact entomopathogenic nematodes (EPNs), beneficial nematodes that that are important biocontrol agents of pest insects, and how these effects might differ from those of chemical fertilizers. In field experiments the effects on Heterorhabditis marelatus and Steinernema carpocapsae EPNs of a mixture of chicken and cow manure, versus those of the synthetic dry formulated complete fertilizer were compared. Fertilizer was applied to field plots of potato (Solanum tuberosum) and EPN were released, then tracked for persistence using sentinel Galleria mellonella and Leptinotarsa decemlineata larvae. In two different years, EPN infection rates were lower, and EPN persistence shorter, in plots receiving animal manure fertilizer than in those receiving chemical fertilizer. The microbial activity, measured using a dehydrogenase enzyme activity measurement, was greater in manure than chemical fertilizer plots. Endemic pathogens were also recovered, but densities of these species were not altered by our fertilizer or EPN release treatments. There was no evidence that competition by resident entomopathogens contributed to the negative effect of animal manure on EPNs. Soil pH and soil moisture were not different between the two fertilizer types. These results suggest that biotic resistance from increased microbial activity with animal manure and not competition by resident entomopathogens, or the moisture levels or soil chemistry, reduced EPN effectiveness. The results suggest that there may be a conflict between using animal manures to manage soil fertility, and EPNs as insect biocontrol agents.