Hellula undalis (cabbage webworm)

The young larvae mine leaves, bore stems and feed externally on the leaves; they then often penetrate the heart of the plant destroying the terminal bud, and prevent heading. While feeding they spin a silken tube. Plants wilt, and frass is exuded from the affected plant parts.

Introduction

H. undalis frequently occurs in the same areas where the diamond back moth [Plutella xyolestella] is regarded as a major pest of Cruciferae. This complicates the control measures applied to H. undalis, since measures used to control P. xylostella may adversely affect measures used to control H. undalis (including H. undalis' natural enemies).

Biological Control

Dreyer (1987) found that weekly applications of simple neem products afforded good control in Togo.

Host-Plant Resistance

Srihari and Satyanarayana (1992) tested eight hybrids for resistance and found that TKCBN25 sustained the lowest H. undalis damage.

Lal et al. (1991) tested 64 cultivars of cauliflower in India. None was highly resistant, but the least infested variety was ES-9.

In Taiwan, it was found that variety B197 of Chinese cabbage was the least damaged by H. undalis (AVRDC, 1987). In 1979, research at the same centre found B159, B186, B488 and B501 to be the least affected by H. undalis.

H. undalis is a serious pest of Brassicae and other crucifers in warm regions where it occurs. Without any control the yield loss in India amounts to 30% (Srihari and Satyanarayana, 1992).