Effects of adult diaprepes root weevil on leaf gas exchange and growth of buttonwood and live oak

Alex Diaz, Catharine Mannion, Bruce Schaffer

Abstract


Diaprepes root weevils Diaprepes abbreviatus L. (Coleoptera: Curculionidae), feed on a wide variety of ornamental plants grown in southern Florida. Although most damage to plants is caused by larval root feeding, adult leaf feeding has been observed to cause moderate to severe defoliation. Studies were conducted to evaluate the effects of adult Diaprepes root weevil leaf feeding on net CO[sub2] assimilation, stomatal conductance, transpiration and growth of buttonwood (Conocarpus erectus L.) and live oak (Quercus virginiana Mill.). Leaf gas exchange of buttonwood in two separate experiments showed variable results. In the first experiment leaf gas exchange of young and mature leaves were not affected by adult weevil leaf feeding. In the second experiment, after 2 months mature leaves of infested plants had higher net CO[sub2] assimilation, stomatal conductance and transpiration than controls. In both experiments leaf area of buttonwood tended to be less for infested plants than non-infested plants. Leaf, stem and root weight of buttonwood was not affected by weevil infestation in the first experiment. In the second experiment root weight of buttonwood was lower for the infested plants than the non-infested plants. In a third experiment, leaf gas exchange of live oak was not affected by adult leaf feeding. Adult weevils did not cause any significant damage to live oak foliage and leaf gas exchange was not affected by herbivory. Live oaks did not produce any new leaves during the treatment period and all weevils died within a month.

Keywords


quercus virginiana; conocarpus erectus; net CO[sub2] assimilation; stomatal conductance; transpiration

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283