Author: Zeller, 1847
Cotton tipworm
Cotton tortricid
Species Overview:
Adult: 12-16 mm wingspan; forewing cream- or ochreous-white, suffused with ochreous and weakly strigulated with fuscous; markings greyish, basal patch obsolescent costally, median fascia poorly defined, and pre-tornal marking triangular; hindwing grey, with large cubital pecten in males.
Egg: usually deposited adjacent to prominent veins on the undersurface of leaves; also on seed capsules (on Malva parfivlora) or squares and bolls (on Gossypium hirsutum).
Larva: 10-11 mm long; head yellowish to blackish brown, region of stemmata and postero-lateral margins black; prothoracic plate dark yellowish brown; abdomen yellowish brown to dark reddish brown; pinacula concolorous with integument, small; anal plate weakly sclerotized, rounded posteriorly; anal comb present, moderately developed.
Pupa: slender, pale yellowish brown; in a flimsy silken cocoon spun up amongst leaf litter.
Taxonomic Description:
Male:
Crocidosema plebejana adults
Crocidosema plebejana adult
External characters: 12-16 mm wingspan; forewing cream-white or ochreous-white, variably suffused with ochreous and weakly strigulated with fuscous, a few plumbeous striae arising from costal strigulae in apical half; markings ochreous-grey, with an admixture of dark brown and black; basal and sub-basal fasciae forming a diffuse basal patch, obsolescent costally, its outer edge obliquely curved from costa to dorsum, sometimes obtusely angulated medially; median fascia poorly defined, usually lacking blackish admixture, confluent dorsally with a comparatively well-defined, triangular pre-tornal marking; subterminal fascia arising from a little below middle of termen, dilated in upper part of distal area and marked with a blackish dash; a blackish apical spot; ocellar area white suffused with grey and edged with silver, containing two or three black dots or dashes; cilia cream-white, suffused with ochreous and sprinkled with fuscous-grey, most strongly at apex. Hindwing grey, weakly dappled with darker grey apically; cilia whitish grey, with a dark sub-basal line. Cubital pecten on hindwing large and prominent, light ochreous-grey (Bradley et al., 1979).
male genitalia C. plebejana
Genitalia: Uncus rudimentary; gnathos in form of a subanal plate. Socii very large, curved outwards. Valva broad, with deep notch in ventral margin; cucullus larger than basal part of valva, bristled and provided with one or more large spinescent setae on outer surface.
Female:
External characters: Hindwing lacking the conspicuous pecten at base of cubital vein. Forewing colouration and markings similar to those of male.
female genitalia C. plebejana
Genitalia: Sterigma reduced to a median aciculate postvaginal patch; distal part of ductus bursae sclerotic except for the dorsal portion; cingulum long, folded; ductus seminalis extending from middle of cingulum; signa large. 7th sternite provided with postmedian lobes with a weak terminal portion.
Variation:
The intensity of the ochreous suffusion of the forewing ground colour and the strength of the markings vary considerably. In well-marked specimens the basal patch is usually stronger costally; the curvature of the outer edge of this patch also varies and can be irregular (Bradley et al., 1979).
Biology:
Europe:
A bivoltine species. Moths fly from July until August and in October. Larvae are found from June until September or October, feeding in the seed capsules and occasionally in the shoots of the host plant. The larva moves from one capsule to another, boring a hole through the side of the fresh capsule; two holes in a capsule usually indicate that the larva has left. Pupation occurs in a flimsy silken cocoon spun up amongst leaf litter (Bradley et al., 1979).
Australia:
Overwintering adults move from adjacent, senescent malvaceous weeds into the seedling cotton fields, where oviposition occurs in November. Larvae feed on plant tips and reach the final instar in December, before the crop flowers. The larvae drop to the soil, where pupation takes place. In January, emerging adults move from cotton fields to the malvaceous weed Anoda, and later, in autumn, they migrate to their primary annual host plant Malva parviflora, on which several generations of the tipworm may develop from March to November. Spring rains may induce the germination of a generation of Malva parviflora in September. These plants develop very rapidly and provide a source of food to the tipworms when other plants are scarce. They are usually very heavily infested by this insect. Cool, wet weather in the period from March to November favours the growth of Malva parviflora and results in often heavy infestations of the cotton seedlings. Infestations are much less serious in dry years (Geest van der et al., 1991).
North America
Moths collected in September. Larvae feed in seeds, fruits, and flowers of various Malvaceae.
Host plants:
Cucurbita pepo, Abelmoschus esculentus, Abutilon avicennae, Abutilon indicum, Althaea rosea, Anoda cristata, Gossypium sp., Hibiscus esculentus, Hibiscus militaris, Hibiscus rosa-sinensis, Kosteletzkya althaeifolia, Lavatera arborea, Malva parviflora, Malvastrum sp., Malvaviscus sp., Sida rhombifolia, Sida cordifolia, Eucalyptus sp., Crataegus sp., Salix safsaf, Turnera ulmifolia, Foeniculum pifieratum, Zea mays.
Damage:
On cotton: seedlings of cotton can suffer serious damage caused by the cotton tipworm. Growing parts of the seedlings are attacked and the subsequent delay in plant development can cause exposure of maturing bolls to unfavourable weather and to other pests. Damage varies from year to year (Geest van der et al., 1991).
In Japan, the species has been recorded as a pest of commercial grown okra fruits (Nasu and Yasuda, 1993).
Distribution:
Southern Europe from UK, France, Denmark, Germany, Cyprus, Spain and Italy to the Balkan Peninsula; Northern Africa: Egypt, Morocco, Sudan; Asia Minor, Ukraine, Trans-Caucasus, Turkmenistan; Iran, India, Thailand, Taiwan, Japan; North America: Texas and California; South America: Peru, Ecuador, Galapagos Islands; Australia.
Pheromone:
Pheromone unknown.
Parasitoids:
Microbracon kirkpatricki Z. (Braconidae)