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Title: EFFECT OF DIETARY COPPER ON LARVAL DEVELOPMENT OF DIAPREPES ABBREVIATUS (COLEOPTERA: CURCULIONIDAE)

Author
item Lapointe, Stephen
item Weathersbee Iii, Albert
item DOOSTDAR, HAMED - MORSE ENTERPRISES
item MAYER, RICHARD - 6618-05-10

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/22/2003
Publication Date: 1/28/2004
Citation: Lapointe, S.L., Weathersbee, A.A., Doostdar, H., and Mayer, R.T. 2004. Effect of dietary copper on larval development of Diaprepes abbreviatus (Coleoptera: Curculionidae). Florida Entomologist. 87(1):25-29.

Interpretive Summary: The Diaprepes root weevil causes extensive damage to citrus trees in Florida and the Caribbean through the feeding of larvae on the tree roots. It was suggested that the copper ion present in common copper fungicides might be used to control larvae based on its ability to inhibit digestive enzymes of the Diaprepes root weevil. Increasing copper concentration in an artificial diet reduced the weight gain of young larvae, but not older larvae. However, significant negative effects on the larvae were only observed at copper concentrations that are toxic to the plant. In another greenhouse study, no effect on larvae was observed when copper solutions were applied to potted citrus trees. The potential for manipulating citrus tree copper content to control this pest appears to be minimal.

Technical Abstract: Larvae of the Diaprepes root weevil, Diaprepes abbreviatus (L.), were reared from hatching on an artificial diet containing four concentrations of two copper compounds, cupric sulfate (CuSO4) or cupric hydroxide [Cu(OH2)]. Negative effects of copper on insect development were observed only for early instar larvae. Survival of larvae from hatching to 4 weeks of age was significantly affected by the copper compounds compared with the artificial diet alone, and more mortality was associated with CuSO4 compared with Cu(OH2). The two compounds had equivalent effects on larval weight gain of early instar larvae. Weight gain was negatively correlated with increasing copper concentration. No effect of copper was observed on late instar larvae (>30 d old). For these larvae, larval and pupal period, weight gain, and survival were statistically similar when reared on all diet treatments including the control. No effect on larval survival or weight gain was observed when copper solutions were applied at nonphytotoxic levels to two varieties of citrus rootstock. The potential for manipulating citrus tree copper content to control this pest is discussed.