D3211: The potential to use multi-modal light and pheromone stimuli for maize weevil and larger grain borer

Insects typically are thought to live in a chemical world, however visual cues are also important for foraging. Different wavelengths of light may be more or less attractive, and the intensity of light may also affect the behavioral response by insects. Stored product insects, or those that infest commodities after harvest, are economically important with global losses exceeding $100 billion. Current monitoring tools only take advantage of pheromones or food cues, but enhanced tools could include multiple modalities such as light, and be a powerful new detection method. Thus, the aims of our study were to 1) evaluate preference by the stored product insects, Sitophilus zeamais and Prostephanus truncatus to different wavelengths of light in a five-way light olfactometer, 2) elucidate the effect of light intensity using a variable resistor on the optimal wavelength found in (1), and 3) evaluate taxis to conspecific pheromone alone, the optimal light at optimal intensity alone, or both pheromone + light together in a wind tunnel. We hypothesized that light would enhance attraction based on the fact that other stored product insects have been known to use both visual and chemical cues. We found one of the five wavelengths was optimal, but at less than full brightness for both species. Using both stimuli together resulted in greater attraction than either alone, suggesting promise for multi-modality as a tactic in monitoring. Overall, our work suggests a synergistic effect of adding pheromone and light together.