Monday, December 10, 2007 - 8:29 AM

Sensory studies of a willow-feeding leaf beetle, Calligrapha verrucosa (Coleoptera: Chrysomelidae)

Mark H. Goodman,, Brigham Young University, Department of Biology, BYU MLBM 325, Provo, UT and Gary M. Booth, Brigham Young University, Department of Plant and Animal Sciences, BYU, Provo, UT.

The willow-feeding leaf beetle Calligrapha verrucosa was collected from populations found feeding on common sandbar willow Salix exigua, along the Humboldt River in Nevada. F2 beetles from these populations, raised in a laboratory setting, were used in experiments to determine both their method of food source recognition and host-plant specificity.

Beetles were individually placed in a Petri dish with one of several stimuli, including S. exigua. Their paths in reaching and success in finding the stimulus were timed and recorded, testing their ability to find food in a short vision field.

An eight-arm olfactometer was used to determine the part smell played in food detection. Beetles were placed individually in the olfactometer, while paths were timed and recorded.

Results from these experiments indicate that the beetles are unable to effectively identify a suitable food source from a distance, even in short range. However, choice and no-choice food tests showed that there is a general selectivity for plants of the genus Salix. In no-choice tests beetles consumed some other plants, but the beetles fed exclusively on Salix when presented with a choice of plants. In these tests they showed no preference in which plant they approached first. It seems that they are able to effectively determine food value only when in close contact with it.

SEM images were also taken of the antennae, maxillary palps, and labial palps, revealing the types and number of sensilla on them, and may shed some light on food detection strategy.

Species 1: Coleoptera Chrysomelidae Calligrapha verrucosa