Anticarsia gemmatalis (Hübner)

Scientific Name Anticarsia gemmatalis (Hübner)
Common Names English: Woolly pyrol moth, Velvetbean caterpillar; Spanish: Gusano terciopelo de la soya, Isoca de las leguminosas
Description Both adults and larvae of this species are extremely variable in coloration. Most caterpillars are green, but some are brown or black, and they have distinct lengthwise stripes in yellowish white or pink. They can become nearly 50 mm (1.97 inch) long and are remarkably active. Young instars are sometimes misidentified as soybean loopers (Pseudoplusia includens).
The adult has a wingspan of up to 40 mm (1.57 inch); its color is gray to light brown. The wings may be nearly without markings or can be heavily speckled; other individuals show a dark band on the wings.

Biology

Damage

The caterpillars of A. gemmatalis - often appearing in very large numbers - attack leaves of soybean and other crops. The young larvae start feeding on the soft tissue, thus skeletonizing the leaves. Older instars, which are active primarily at night, consume the leaf veins, too. The caterpillars proceed either from the top or the bottom of plants towards the middle part of the foliage. When most of the leaves have been devoured, stems, buds and young pods are destroyed as well. The larvae of A. gemmatalis are able to defoliate a field of soybean completely within a week.

Lifecycle

The eggs are laid singly, normally on the undersides of leaves, but when infestation is severe, they can be found on all aerial parts of the plant. After 3-7 days, the larvae hatch. Larval development comprises six instars and during the summer, it can be completed in about two weeks (and the complete life cycle in four weeks). At lower temperatures, more time is required. The duration of the sixth instar is particularly variable: it can last between 6 and 24 days. The caterpillars are unusually active. When disturbed, they let themselves drop from leaves immediately, and they try to wriggle out of the grip when picked up.
For pupation, the larvae build a cell from earth particles either on, or directly under, the soil surface, at most 20 mm 80.78 inch) deep. The adult moth emerges after 7-11 days.
Anticarsia gemmatalis is found throughout the Americas, from Canada to Argentina. The number of generations per year varies between regions, depending on the local climate and the seasonal availability of host plants. In the (sub-)tropical core area of A. gemmatalis, all development stages can be found at any time.
The moth migrates each year into the south-eastern United States, where the caterpillars generally appear after midsummer. In the south of both Florida and Texas, however, overwintering populations have established.

Occurrence

Additional Crop Information

A. gemmatalis feeds on a great number of Fabaceae (beans, peas, alfalfa, groundnut etc.), but soybeans are the preferred host.

Agricultural Importance

Occasionally, A. gemmatalis may cause losses of up to 100%. Its host plants include several very important crops; some of them (e.g. beans and peanut) are indispensable staple foods in Middle and South America. The insect is one of the most important pests of soybean.

Control

Integrated Crop Management

Choosing early-maturing cultivars and early planting can reduce damage in soybean.

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