Dispersal of adult Colorado potato beetles (Coleoptera: Chrysomelidae) on plant models

AbstractFive artificial plant models mimicking potato plants, each having different and increasing numbers of structural components, were used to observe individual adult Colorado potato beetles (Leptinotarsa decemlineata (Say); Coleoptera: Chrysomelidae) over a period of 6 hours. The objective was to determine if plant architecture affected residency time, within plant dispersal, and distribution of the species. The number of transitions between sections, the time spent on each section, the residency time on each model, and the proportion of individuals walking off were recorded. Results showed a positive relationship between the proportion of beetles remaining after 6 hours and the number of connections on respective models. The unexpectedly long residency on all but the simplest model in spite of the absence of food indicates that architectural complexity had an impact on beetle retention. Dispersal activity and residency time were heavily skewed towards the top of models. Beetles exposed to positive light gradients of different intensities and a negative light gradient showed that a phototactic response could explain much of the dispersal pattern to the upper model sections. Results show that manipulation of plant structure remains an option for managing the beetle but will require further research on the contribution of heterogeneity and scale to residency time.