LADY BEETLES AS POTENTIAL PREDATORS OF THE ROOT WEEVIL DIAPREPES ABBREVIATUS (COLEOPTERA: CURCULIONIDAE) IN FLORIDA CITRUS

Abstract

Diaprepes abbreviatus (L.) is a major pest of Florida citrus. Adult females lay eggs in masses sealed between leaves in the citrus canopy, and recently-hatched neonate larvae drop to the soil and feed on roots. The coccinellid species, Cycloneda sanguinea (L.), Harmoniaaxyridis Pallas, and Olla v-nigrum Mulsant, are generalist predators that consume a wide range of citrus pests, although they have not been observed preying on Diaprepes. We conducted experiments to determine whether these species would feed on Diaprepes egg masses and neonate larvae, and how an exclusive or partial diet of Diaprepes eggs would influence their development. The three predators responded very similarly in our tests. In laboratory assays, coccinellid larvae and adults readily consumed exposed Diaprepes eggs and neonates less than 48 h old; and coccinellid larvae preyed on 40% of intact egg masses laid between wax paper strips or citrus leaves, whereas adults preyed on 8.7%. In a greenhouse assay, coccinellid larvae located and preyed on 22.7% of intact egg masses laid between leaves on potted citrus trees. Although neonates might have relatively limited exposure to predation in the canopy before they drop to the soil, predation could be an important factor selecting for the timing of egg hatch, neonate escape from leaf envelopes, and neonate drop. The developmental assays indicate that Diaprepes eggs are less suitable prey for these coccinellid species than eggs of the flour moth, Ephestia kuhniella Zeller, but that they could be a highly acceptable component of a mixed diet. Our experiments indicate that these coccinellid species are potentially important predators of Diaprepes but the extent to which they contribute to the natural biological control of this weevil remains unknown.

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