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

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(OH)2]. Negative effects of copper on insect development were observed only for early instars. Survival of larvae from hatching to 4 weeks of age was significantly affected by the copper compounds compared with the artificial diet alone, and greater mortality was associated with CuSO4 compared with Cu(OH)2. The two compounds had equivalent effects on larval weight gain of early instars. Weight gain was negatively correlated with increasing copper concentration. No effect of copper was observed on late instars maintained on these diets beyond the initial 4 weeks. Larval and pupal period, weight gain, and survival of late instars were statistically similar. 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.