Beet Armyworm Spodoptera exigua (Lepidoptera: Noctuidae): a Major Pest of Welsh Onion in Vietnam

Abstract

The beet armyworm Spodoptera exigua is known as a pest of Welsh onion or green bunching onion, an important fresh vegetable in many Asian countries. Here, a survey was conducted in farmers' fields to investigate the infestation of green bunching onion by the beet armyworm in relation to plant growing stages. Although the infestation levels differed among study fields and between seasons, high levels of infestation were often detected, indicating that chemical control did not work well. All growing stages of onion were attacked by the armyworm though there was a positive relationship between plant heights and infestation levels. The youngest class of stages, i.e., seedling, was much less frequently damaged. The results indicate that the management of the beet armyworm including IPM practices is essential to stable production of marketable Welsh onion.