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Spodoptera Guenee

Type species: mauritia Boisduval.

Synonyms: Laphygma Guenee (type species exigua Hubner, Old World tropics); Prodenia Guenee (type species retina Freyer = littoralis Boisduval, Africa); Rusidrina Staudinger (type species rasdolnia Staudinger = depravata Butler, Japan, China, Korea); Calogramma Guenee (type species picta Guerin Meneville).

This genus contains a very high proportion of agricultural pest species (cutworms and armyworms) and a number of other interesting taxa, one of which is used as an agent for water-weed control. Much time has been invested in studies of biology, behaviour, pheromones, migration etc., but surprisingly no attempt has been made to derive a modern phylogenetic classification as a framework for these observations.

African and New World taxa have been reviewed by Brown & Dewhurst (1975) and Todd & Poole (1980b). The genus as a whole is currently under study by Dr I.J. Kitching, who plans to provide a phylogenetic hypothesis for it.

The species have dull grey or brown forewings, the males more contrasted than the females, or a more reticulate, striate pattern, again with minor sexual dimorphism. The hindwings of the Old World taxa are, with one exception, white, often nacreous, usually with a narrow brown border, sometimes with the veins distally delineated brown also.

The male antennae can be bipectinate or ciliate, the female antennae ciliate.

In the male abdomen there are no basal hair pencils, but the basal sternite is relatively short, with narrow, ovate lacunae associated with the apodemes. The eighth sternite has lateral rods. In the genitalia the valves have basal, external, sometimes double coremata, unusual in trifines, and seen here only in some Acronictinae, in the hadenine Tiracola Walker; they are more distal on the valve in Elusa Walker. The sacculi of the valves lie adjacent, and are sometimes fused along straight inner margins. The valves have a slight cucullus, with an extremely distal spined process associated with a less sclerotised zone that passes between cucullus and sacculus to the ventral notch between the two. Subbasally on or just ventral to the valve costa is a small ampullate process that, from species to species, appears to be long if it is close to the costal margin, but very short if interior to it. Homology of the distal spine to the costal process of higher trifines, and of the ampullate process to the harpe is a feasible hypothesis, but requires further investigation. The aedeagus often has sclerotised bands extending in to the vesica as in some higher trifines.

In the female genitalia the eighth segment is much expanded into a lightly sclerotised, greyish membrane bearing a dense layer of scales that is deposited on the egg mass. The apodemes of the eighth segment are sometimes only vestigial (e.g. in S. pecten). The ostium and base of the ductus are strongly and darkly sclerotised; the ductus distally becomes less sclerotised but scobinate and fluted. This scobination and fluting is seen also in the very basal part of the bursa. The bursa contains a single short to moderate signum, a scobinate band; this is another feature that may associate the genus with the higher trifines.

The larvae are typical trifines with primary setae only. They are often strikingly marked, particularly with subdorsal rows of black streaks or lunules, though rarely colourful. All African taxa, many of which are Oriental also, are illustrated and described by Brown & Dewhurst (1975) who also give keys to larvae and some pupae.

Most species are highly polyphagous, though there is some tendency for them to be either graminaceous or dicotyledonous feeders. Two more specialist taxa, S. pectinicornis Swinhoe and S. picta Guerin-Meneville, are described below.

Full synonymies for S. mauritia Boisduval, S. cilium Guenee and S. pecten are not given, as several items need checking.

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