Submitted to: International Society of Citriculture Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2003
Publication Date: February 15, 2004
Citation: Lapointe, S.L., Shatters, R.G. 2004. Traditional and transgenic approaches to control of the diaprepes root weevil. International Society of Citriculture Abstracts. Interpretive Summary: The Diaprepes root weevil has become a major constraint to the profitability of citrus production in large areas of central and southern Florida. The species originated in the Caribbean and has recently extended its range to Texas in the USA and threatens California. Damage by larval feeding on citrus roots can be severe and feeding can lead to damage by root diseases. Attempts to identify naturally resistant citrus plants have failed to find meaningful resistance, although some plants are tolerant to the damage caused. The use of transgenic rootstocks is a viable alternative. This can be done through the use of bacterial genes that code for proteins that are toxic to insect, or through the use of genes that code for blockers of digestive enzymes, thereby interfering with food digestion by the insect. We present recent data to show the feasibility of these approaches.
Technical Abstract: The Diaprepes root weevil, Diaprepes abbreviatus (L.), is a major constraint to the profitability of citrus production in central and southern Florida. The species originated in the Caribbean and has extended its range to Texas and threatens California. Damage by larval feeding on citrus roots can be severe through girdling of major roots and by facilitating infection by root rot organisms. Greenhouse screens of sexually compatible citrus germplasm have identified low levels of plant resistance in Poncirus trifoliata that are of insufficient magnitude to provide protection in the field. Data from greenhouse tests to demonstrate resistance in P. trifoliata, and results from field trials to demonstrate tolerance to larval feeding will be presented. An alternative to traditional breeding is development of transgenic rootstocks for expression of toxins such as that from Bacillus thuringiensis, or of inhibitors of digestive enzymes. A new high volume bioassay using neonate larvae will be described along with results that demonstrate the efficacy of specific inhibitors on the growth and survival of larval D. abbreviatus. Decreased weight gain and increased mortality of neonates exposed to artificial diet containing inhibitors of specific digestive enzymes demonstrates the feasibility of this approach.