Author
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Jewett, Darryl |
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BJOSTAD, L - COLORADO STATE UNIV |
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Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/11/1996 Publication Date: N/A Citation: N/A Interpretive Summary: The western corn rootworm (WCR) is the most economically important insect in the United States; requiring more than one billion dollars annually for its control. Management has relied primarily upon soil-insecticide applications, but the need for an alternative strategy has been expressed because of concerns for resistance and the environment. In response to this need, attractants of larvae have been evaluated for compatibility with current management practices; and the goal of developing more convenient formulations with increased ranges of activity has inspired researchers to consider synthetic analogs. Dichloromethane (MeCl2) is a laboratory solvent frequently used to study chemical attractants of insects. Coincidentally, it is also the first organic compound reported to attract diabroticite larvae. Carbon dioxide (CO2) is also recognized as an attractant of WCR larvae, and of many other agriculturally and medically important invertebrates. CO2 and MeCl2 may behave analogously when they interact with chemoreceptor sites on larvae. If this relationship is confirmed, new chemical attractants may be available for improved agriculture or for reduced incidence of invertebrate-spread diseases. Presently, because many invertebrates are attracted by MeCl2, results obtained from its use should be regarded critically Technical Abstract: A two-choice behavioral bioassay was used to demonstrate that dichloromethane (MeCl2) elicits dose-dependent attraction of 2nd- instar western corn rootworm (WCR) and southern corn rootworm (SCR) larvae. Preliminary data suggest that 2nd-instar banded cucumber beetle larvae are also attracted to MeCl2. An eluotropic series of 10 solvents was tested for attraction of WCR larvae. MeCl2 was the only one attractive at all doses tested, and orthogonal comparisons revealed a quadratic trend with increasing dose. Benzene and hexadecane also attracted larvae, but significantly fewer numbers than MeCl2, and only at 3 doses and 1 dose, respectively. Orthogonal comparisons revealed no trend for responses of larvae to increasing dose of either compound. MeCl2 attracts WCR larvae in the absence of carbon dioxide (CO2), which has previously been demonstrated to attract WCR larvae either independently or when combined with other organic compounds. The sensitivity of our bioassay was tested by demonstrating the dose-dependent attraction of WCR larvae to carbonated water as a CO2 source. We have also demonstrated the attraction of SCR larvae to CO2, and propose that MeCl2 and CO2 behave analogously when they interact with chemoreceptor sites on larvae |
