Patterns of honeydew droplet production by nymphal stages of Bemisia argentifolii (Homoptera : Aleyrodidae) and relative composition of honeydew sugars

Honeydew droplets were collected from nymphal and adult Bemisia argentifoli i Bellows and Perring. Nymphs produced a regular pattern of honeydew drople ts consisting of periods of production followed by periods where no droplet s were produced. The mean length of individual production periods increased from the second (40 +/- 1 min) to the fourth (162 +/- 11 min) stadium, unt il the late fourth stadium when honeydew production by most nymphs became c ontinuous. In contrast, the periods of no production decreased in length as nymphs developed from the second (35 +/- 1 min) to the fourth (23 +/- 1 mi n) stadium. The frequency of droplets during the production periods decreas ed from the first (80 +/- 1 drops per h) to the fourth (22 +/- 1 drops per h) stadium. This periodic pattern is consistent with previous reports for T rialeurodes vaporariorum (Westwood), however, the functional significance o f this pattern remains unknown. if this cyclic pattern should prove critica l to the successful feeding and development of whiteflies, its disruption m ay decrease survival and provide a novel target for pest control strategies . Second and third instars had higher percentages of di- acid trisaccharide s (sucrose, trehalulose, and melezitose) and lower percentages of monosacch arides (fructose and glucose) compared to first and fourth instars. This co uld indicate a change in metabolic needs of nymphs during periods of rapid growth, or indicate that trehalulose synthase producing endosymbiotic bacte ria are more abundant, or more actively producing enzyme during the second and third stadia.