Ostrinia nubilalis (Hb.) (Lep., Pyralidae) on sweet corn: relationship between adults caught in multibaited traps and ear damages

Infestation with Ostrinia nubilalis (Hb.), the European corn borer (ECB) ca n be detected by using different sampling techniques in the field and stati stical models aimed to assess the development time of ECB larvae and crop d amage. An appropriate monitoring for this polyphagous species to show a rel ationship between the kind of sampling or a model and the subsequent damage in a particular crop, is very difficult. Sex pheromone traps, generally, a re also not reliable for monitoring ECB. The possibility of employing new t ypes of traps baited with a sex pheromone and a maize kairomone, the phenyl acetaldheyde (PAA) (multibaited traps) was investigated. In sweet corn, tra pping experiments were conducted over a 2-year period with two kinds of con e traps (XLa and XLb) set up at the borders of fields (four replicates). EC B attacks of first and second generation larvae were evaluated in the corn ears as a percentage of damage and using a damage index (DI). A correlation was found between the number of females caught per trap and either the per centage of damaged ears (r = 0.73 for XLa; r = 0.65 for XLb) and the DI (r = 70 for XLa; r = 0.60 for XLb). Conversely, the number of males caught per trap was not correlated with ECB larval damage. A linear model of multiple correlation fitted to the data of simultaneous captures of males and femal es showed that the coefficients were not higher than simple correlation. Th e correlation coefficients obtained by fitting a curvilinear response surfa ce were higher (r = 0.81 for XLa and r = 0.84 for XLb, respectively, relate d to percentage of damaged ears; r = 0.79 for XLa and r = 0.76 for XLb, res pectively, related to DI) thus indicating that the simultaneous counting of males and females in cone traps can be an efficient and simple monitoring tool.