|Schnell ii, Raymond|
Submitted to: Journal of Applied Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/29/2005
Publication Date: 7/11/2005
Citation: Puche, H., Weissling, T., Schnell Ii, R.J., Epsky, N.D., Heath, R.R. 2005. Estimating dispersal rate of the silky cane weevil (coleoptera: curculionodae). Journal of Applied Entomology. 129(6): 293-299. Interpretive Summary: The silky cane weevil was first introduced into Florida in the mid-1980s and has since become a serious pest of sugarcane as well as several ornamental plant species that are grown in Florida. Information on dispersal rates for this and other pest insects is needed to predict pest spread and for decisions needed in pest management programs. Therefore, scientists at the Subtropical Horticulture Research Station conducted release-recapture trapping studies in a screen enclosure to monitor insect movement within 48 h of initial release, and a passive diffusion model was used to estimate weevil dispersal rate. This study found that weevils were concentrated initially around the release point and moved slowly towards the boundaries of the screened enclosure over time, with an average speed of 60.1 + 3.0 cm / h. This study demonstrated the value of release/recapture experiments to quantify dispersal rates for this insect and presented baseline data that will be used to determine the effect of factors such as sugarcane variety or presence of attractants on insect movement. Information on the rate of dispersal can be used to predict pest outbreaks and patterns of host selection and to generate optimal indicators of the predictability and reliability of potential control techniques, all important factors needed to reduce weevil damage and to manage the pest in areas where it occurs.
Technical Abstract: The objective of this study was to estimate the silky cane weevil rate of dispersal inside a screen enclosure. One hundred weevils were released inside a screened enclosure and weevils were counted hourly for eight hours, and then 24 and 48 h after release. A passive diffusion model was used to estimate the weevil's dispersal and disappearance rates, within and between rows. The weevils concentrated around the release point and slowly moved towards the boundaries of the experimental plot over time, and had an average speed of movement of 60.1 + 3.0 cm / h (mean + SE). Dispersal and disappearance rates within and between rows were not significantly different among the time intervals considered (1-8, 8-24 and 24-48 h after release) except for the 1-8 time interval when the dispersal rate, D was significantly higher than those at other time intervals. Continuum of the substratum to disperse from one side of the array to another via a wooden bridge may explain the higher dispersal rate through this array. The number of buckets exposed to the sun during the morning hours was significantly higher on those rows exposed to the sun for more hours (south side of the screen enclosure) than on the shaded side. These data may give insights into managing infestations of this weevil in South Florida.