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Title: STRUCTURE-ACTIVITY STUDY WITH HALOALKANE ATTRACTANTS OF WESTERN CORN ROOTWORM LARVAE USING A BEHAVIORAL BIOASSAY

Author
item Jewett, Darryl
item BJOSTAD, L. - COLORADO STATE UNIVERSITY

Submitted to: Journal of Entomological Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: The western corn rootworm (WCR) is the most economically important insect in the United States because annual crop losses and treatment costs associated with it have been estimated at one billion dollars. Management has relied primarily upon soil- insecticides, but the need for alternatives has been expressed because of concerns for the environment. In response to this need, attractants of larvae are being sought in anticipation that they can be combined with relatively lower amounts of insecticides in a formulation informally referred to as an attracticide. Dichloromethane (MeCl2) was previously demonstrated to attract WCR larvae in laboratory bioassays, and has many commercially available synthetic analogs, which presents a novel opportunity to study the relationship between its structure and activity. Carbon dioxide (CO2) is also recognized as an attractant of WCR larvae, and of many other agriculturally or medically important invertebrates. CO2 and MeCl2 may behave analogously when they interact with chemoreceptor sites on larvae. If this relationship is confirmed, identifying other materials with similar structures and activities may result in technology for improved agricultural practices or for the reduced incidence of invertebrate spread diseases.

Technical Abstract: A two-choice laboratory behavioral bioassay was used to compare the dose-dependent responses of second-instar western corn rootworm larvae to a series of structurally related haloalkanes, including ones with different halogens, degree of halogen substitution, chain lengths, and degree of saturation. All the structural parameters that were considered in this study influenced the behavior of larvae. Attraction was inversely related to chain-length, and larvae were even repelled by two doses of 1,1-dichlorobutane, the compound of greatest chain length tested. Disubstituted bromine and iodine analogs of dichloromethane attracted larvae at all doses tested, including 0.5, 1.0, 2.0, and 4.0 mg. Dibromomethane attracted significantly more larvae than dichloromethane at the lowest dose tested (0.5 mg). Analogs of dichloromethane with more chlorine substitutions attracted significantly fewer larvae except for chloroform, which attracted significantly more larvae than dichloromethane at the lowest dose tested (0.5 mg). 1,1- dichloroethene is an unsaturated analog of 1,1-dichloroethane, and orthogonal comparisons revealed a positive linear trend for responses of larvae to increasing doses of it.