Effects of plant growth regulators on fitness of the Asian citrus psyllid (Diaphorina citri)

Application of plant growth regulators (PGRs) has been found to affect populations of certain plant feeding insects. In past studies, there were differences in the population density of pests when a PGR was applied, in combination with an insecticide or by itself. This could be explained due to the better canopy penetration and coverage by pesticides, or due to the reduced ovipositioning sites on the tree, both a result of reduced plant growth. It is not fully understand why prohexadione -calcium inhibits pest populations, particularly are there plant physiological changes which could play a role? The effect of PGRs on fitness of the Asian citrus psyllid (Diaphorina citri) has not been evaluated. In greenhouse experiments, duration and viability of immatures, adult longevity and reproductive capacity and adult weight were determined. Potted grapefruit plants were treated with different prohexadione - calcium treatments. Adult D. citri, from a colony reared on grapefruit plants, were caged on test plants for oviposition. Adults were then removed and the emerged nymphs were checking daily for ecdysis and survivorship. A pair of emerged adults was re-caged on different plants and the total number of eggs laid were counted daily to determine fecundity rate. Every 3 days the pair was moved to new plant to have available the essential space to oviposite. Results and discussion will be presented.