Tree Growth Regulator Influences Orange striped Oakworm (Lepidoptera: Saturniidae) Development and Survival

Abstract

The influence of the tree growth regulator paclobutrazol [(±)-(R\*,R\*)-B-[(4-chlorophenyl)methyl)]- a -(1,1-dimethylethyl)-1 H -1,2,4-triazole-1-ethanol] on the growth of willow oak, Quercus phellos L., and development and survival of orangestriped oakworm, Anisota senatoria (J. E. Smith), was investigated from 1988 to 1990. Paclobutrazol significantly reduced Q. phellos growth, especially 1 and 2 yr after treatment. The most significant effects of paclobutrazol on A. senatoria development and survival were measured I yr after treatment. Early and late instars differed in their response to paclobutrazol treatments. In laboratory studies, 1yr after treatment, the highest rate of paclobutrazol slowed development and decreased survival of early instars compared with control treatments. Paclobutrazol treatments at the two lowest rates significantly increased survival of late instars and prepupae compared with the highest rate in the laboratory. Accelerated development in the fifth instar occurred with paclobutrazol treatments. At the lowest rate, paclobutrazol treatment significantly increased female pupal weights when larvae were reared in the laboratory and field. These data suggested that Q. phellos injected with paclobutrazol at the two lowest rates may experience a late-ins tar population that has increased survival, development, and female pupal weight.