80 Red bollworm

Red Bollworm

Namibian crop pests # 80

Diparopsis sp.

Order: Lepidoptera

Family: Noctuidae

Note: this species has not been identified by an entomologist yet.
Samples will be sent for identification as soon as possible

Cotton boll with entrance hole	Cotton boll with entrance hole
symptoms on cotton bolls	Caterpillar, 25 mm
Grey form	Red form

Common names:	No vernacular names have been recorded.
Pest status:	The pest status of red bollworm in Namibia is still unknown. Cotton is a new crop under promotion in the country and red bollworms may become more common as the cotton growing area increases.
Distribution:	The first specimen reared from cotton bolls collected at Outapi Agricultural and Rural Development Centre (ARDC) in Omusati region. Similar symptoms were found on cotton bolls at Endobe ARDC, Ohangwena region. Samples were also collected from there but no specimens have been reared yet. Collection is ongoing at other sites.
Description:	The caterpillar grows to a length of 25-30 mm long and is red during the later stages of growth. The caterpillar went into pupation on 2 April 2000 and hatched as imago on 19 April, 17 days later. The adult moth has a wingspan of 30 mm. The wings are grey with olive green markings. A red form was also found among the imagines
Control:	No control is recommended until the pest status of red bollworm has been established.
Other notes:	There are many bollworm species and it may be a coincidence that the first sample turned out to be the red bollworm. Other species may turn out to be more common. Bollworm species have quite different eating habits so it is important to know which bollworms are common (or will become common) on cotton in Namibia. Some species can feed on many different crops or weeds while others are fully dependent on the presence of Cotton or a few related species. A good pest control strategy can therfore only be implemented when we know which species are occurring. It is quite easy to rear bollworms from cotton bolls: Collect a few handfuls of large bolls which have holes in them. Place the bolls in a single layer in a container with 5 cm of sand in the bottom and place a net over the container. Clearly label each sample with locality, date, crop (cotton bolls) and collector. Inspect the containers regularly for hatching moths. Note that the cotton bolls often get mouldy if they are too close to each other.

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