Multicomponent Kairomonal Lures for Southern and Western Corn Rootworms (Coleoptera: Chrysomelidae: Diabrotica spp.)

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Abstract
The attraction of Diabrotica spp. (Coleoptera: Chrysomelidae) to single-component and multicomponent lures was evaluated in corn fields by comparing the relative number of beetles caught on sticky traps over a 24-h period. Initial tests in 1985 showed that a mixture of veratrole (V), indole (I), phenylacetaldehyde (P), trans-anethole (A), and eugenol (E) (=VIPAE mixture) caught 26 times more Diabrotica undecimpunctata howardi Barber, southern corn rootworms (SCR), than untreated control traps and was at least 3 times more active than any of the traps baited with a single component. Significantly fewer D. virgifera virgifera LeConte, western corn rootworms (WCR), were caught on the traps baited with the VIPAE mixture than those baited with 100 mg of trans-anethole. Furthermore, only SCR adults exhibited a concentration-dependent response to the VIPAE mixture. SCR response to the sequential removal of the individual components from the VIPAE mixture suggested the primary attractants to be veratrole, indole, and phenylacetaldehyde. Additional tests showed traps baited with a three-component VIP mixture (veratrole, indole, and phenylacetaldehyde at 20 mg per component) caught ca. 8 times as many beetles as the expected mean additive response with the individual components; therefore, the SCR response was synergistic. The attraction and synergistic response of SCR adults to the VIP mixture was verified by similar tests conducted in 1986. The VIP mixture was also compared with a chemically related mixture consisting of 1,2,4-trimethoxybenzene (substituted for veratrole or ortho-dimethoxybenzene), indole, and trans-cinnamaldehyde (substituted for phenyla-cetaldehyde) (= TIC mixture) at dosages ranging from 1 to 30 mg per trap. Although both mixtures exhibited approximately the same activity for SCR adults, only the new TIC mixture attracted WCR adults. TIC baited traps caught ca. 6 times more WCR adults than did untreated controls at 1 mg per trap and ca. 29 times more WCR adults than controls at 30 mg per trap.