The behavior of early instar tufted apple bud moth, Platynota idaeusalis (Walker) (Lepidoptera: Tortricidae) larvae: Movement and feeding.

摘要

The tufted apple bud moth Platynota idaeusalis (Walker)(Lepidoptera: Tortricidae) is the most important direct pest of apples in the mid-Atlantic states. Injury due to this insect has progressively increased over the last 20 years due to pesticide resistance. To understand the gene flow within populations and manage the resistance, larval feeding and movement behaviour were quantified. Three strains, a laboratory reared azinphosmethyl-susceptible strain, field strain, and a azinphosmethyl-resistant strain were fed on excised apple (Malus domestica (Bork.) cv Red Yorking), peach (Prunus persica (L.) Batsch cv Cresthaven), and cherry (Prunus cerasus L. cv Montmorency) leaves and on a synthetic diet; and the field strain only on unexcised apple, peach, and cherry leaves and also on a synthetic diet. Larval growth characteristics and stage specific survivorship were determined.; Host fed upon influenced larval survivorship and developmental time. Excluding the synthetic diet, feeding on peach resulted in the lowest survivorship, fastest development and heaviest pupal weight for both the excised and unexcised leaf studies. Feeding on cherry resulted in the longest developmental time, lowest pupal weights and best survivorship except in the field strain where apple had the highest survivorship. Overall, the susceptible strain had the best survivorship and the resistant strain the lowest. There were no survivors when the resistant strain fed on peach.; Movement behaviour studies were undertaken in the laboratory in an environmentally-controlled growth chamber; in an open field, and in a young apple orchard. In the laboratory, the proximal factors which influence movement were host, larval density and larval quality. There was also a diel periodicity to larval hatch, and neonates survived for up to five days without feeding. In a separate experiment to refine a technique using rubidium as an elemental marker rubidium was detected in fifth instar larvae of the F{dollar}sb1{dollar} generation.; Dispersal studies were done in the field to test the effects of environmental variables on larval movement. Field dispersal studies were done in a tree-less open area using susceptible and field strain larvae, and in a young apple orchard with field strain larvae. Larvae were trapped on sticky panels arranged at equal distances around a center release point. Larval dispersal was short-range and mediated by local winds. For the open field releases, 95% of the larvae trapped on sticky panels were caught within 15 m from the release point and 99% within 10 m for the orchard release.