Increased Ovipositional Attractancy to Surfactant-Treated Broccoli by the Diamondback Moth (Lepidoptera: Plutellidae): Tests of Potential Mechanisms

Studies were conducted to investigate potential mechanisms by which treatment of broccoli leaves with the surfactant Latron CS-7® causes increased diamondback moth, Plutella xylostella (L.), oviposition. The importance of vision on oviposition was investigated by use of choice and no-choice tests conducted in the presence of light and in complete darkness. Females oviposited 10.7 and 12.8 times as many eggs on treated plants relative to nontreated plants in the presence and absence of light, respectively, indicating that females do not prefer treated plants based solely on visual cues. Greenhouse studies showed that moths continue to lay significantly more eggs on surfactant-treated plants up to 3 d after initial treatment of plants with Latron CS-7. No difference was observed in larval development or survival on treated versus nontreated plants. Scanning electron microscopy indicated a dramatic difference in wax crystallite morphology of surfactant-treated plants relative to nontreated plants. Ovipositional attractancy of surfactant-treated leaves to diamondback moths could be due to a change in mechanoreceptor cues on the leaf surface or volatile compounds released from the leaf surface as a result of altered plant wax micromorphology.