Effect of Removal by Pruning and Mortality Factors during the Larval Stage of Tea Harming Mahasena aurea (Butler) (Lepidoptera, Psychidae)

Abstract

A survey on the vertical distribution on tea hedgerow of the tea harming Mahasena aurea larvae revealed that larval density was highest in the upper layers of the tea trees in mid-May，but the difference between the middle and lower layers gradually decreased. The percentages of removed larvae by light skiffing of canopy (removal of the upper layer) and deep trimming of canopy (removal of the upper and middle layers) in 2017 were 50.8% on June 8^th and 85.4% on July 18^th, respectively. Of the larvae released between the hedges, 18.7% climbed up the tea trees. Larval removal by pruning should be completed by early June before emergence. The highest cause of larval mortality was parasitism by a tachinid Neophryxe psychidis, with parasitism rates were 25.3% on June 8th and 69.6% on July 18^th. The percentages of individuals suspected to have died of disease were 39.7% and 0% on those respective dates. In the future, the development of pest control techniques that combines larval removal by pruning and conservative use of natural enemies are desired.