Effects of Tree Shade on Attacks by the Red Cedar Shoot Borer, Hypsipyla robusta (Moore) (Lepidoptera: Pyralidae)

Abstract

The effects of shade on the attack by Hypsipyla robusta were investigated in red cedar seedlings (Toona ciliata) planted in the open (no shade) and under neem, Azadirachta indica A.Juss. (Meliaceae) shade. Seventy-two T. ciliata were planted in each plot. The trial was regularly monitored, assessing both the physical characteristics of the trees and damage by H. robusta at 12 and 24 months after planting. T. ciliata in the open plot was seriously attacked, with attacks at 12 and 24 months after planting of 93% (2 attacks/tree) and 100% (12 attacks/tree), respectively. T. ciliata planted under shade had no attacks at 12 months, but 43% of the seedlings were attacked (at least one attack/tree) at 24 months after planting. The general performance of T. ciliata trees in the open plot was very poor, while the trees under shade were in good form and taller than the trees in the open planted plot.