Reduced oviposition by Diaprepes abbreviatus (Coleoptera: Curculionidae) and growth enhancement of citrus by Surround particle film

Authors: Lapointe, Stephen; McKenzie, Cindy; Hall, David

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2005
Publication Date: 3/1/2006
Citation: Lapointe, S.L., McKenzie, C.L., Hall, D.G. 2006. Reduced oviposition by Diaprepes abbreviatus (Coleoptera: Curculionidae) and growth enhancement of citrus by surround particle film. Journal of Economic Entomology. 99(1):109-116.

Interpretive Summary: Particle films such as Surround® are an environmentally benign method to deter some insects and diseases of crops. Feeding and oviposition on citrus leaves by the Diaprepes root weevil, a major pest of Florida citrus, has been shown to decline with increasing rates of application of the particle film. This study reports results from a three-year field trial to determine the effect of particle film on tree growth and root weevil damage under field conditions in Florida. Regularly applied sprays of Surround® WP greatly enhanced the growth of citrus trees on a poorly drained soil at Fort Pierce. Surround-treated trees had at least 5 times the mass, 6 times the canopy volume, and approximately 4 times the cross-sectional area of the tree stems at the graft union. The larger Surround-treated trees attracted a higher number of Diaprepes root weevil adults per tree, but an equivalent number of egg masses per tree compared with the control trees. Thus, oviposition per adult was reduced on Surround-treated trees. The number of larvae per tree recovered from the roots of excavated trees was greater from Surround-treated trees compared with control trees. Surround may be an appropriate management tool to optimize citrus tree growth on poorly drained soils. However, the deterrence to oviposition by D. abbreviatus was insufficient to reduce the number of root weevil larvae feeding on the roots.

Technical Abstract: Regularly applied sprays of a particle film (Surround® WP) greatly enhanced the growth of citrus trees on a poorly drained Winder soil at Fort Pierce, FL. After three years of applications every 3 or every 4 weeks, Surround-treated trees had at least 5 times the mass, 6 times the canopy volume, and approximately 4 times the cross-sectional area of the tree stems at the graft union. The larger Surround-treated trees attracted a higher number of Diaprepes root weevil (Diaprepes abbreviatus) adults per tree, but an equivalent number of egg masses per tree compared with the control trees. Thus, oviposition per adult was reduced on Surround-treated trees. The number of larvae per tree recovered from the roots of excavated trees was greater from Surround-treated trees compared with control trees. The data suggest that Surround particle film greatly enhanced the growth of citrus trees grown in a poorly drained soil where trees were stressed by edaphic factors. The deterrence to oviposition by D. abbreviatus was insufficient to significantly reduce the number of root weevil larvae per tree feeding on the roots. However, the more vigorous trees resulting from Surround applications may be more resistant or tolerant to root weevil feeding.