4. Stem borer: Scrobipalpa (=Phthorimaea) heliopa (Gelechiidae: Lepidoptera)

Distribution and Status
Malaya, Indonesia, Australia, New Guinea, Philippines. India especially of FCV tobacco and Natu tobacco in Andhra Pradesh, FCV tobacco in Karnataka State and bidi tobacco in Gujarat. Serious pest of both nursery and mainfield.
Host range: Tobacco, brinjal and solanaceous weeds

Damage symptoms
Tiny caterpillars mine along the leaf stalk into the stem and feed on the internal tissues. Due to larval feeding seedlings and young plants have stem galls and sprouted side branches; plants stunted, distorted and withered.

Bionomics
Larva small, whitish caterpillar, adult very small active brown moth. In bidi tobacco the female moth lays cylindrical eggs singly more on the upper surface than on lower and prefers laying towards the distal half of the upper surface and basal half of the lower surface. A female, on an average, lays 50- 80 eggs. Egg period 4 days, larval period 15-22 days. The full grown larva is pale white in colour, with head and thorax dark brown. The adults after emergence survive for 2-14 days. The total life-cycle extends over 4-5 weeks

Management

• Grow resistant cultivars like Sumatra
• Stem borer affected seedlings should be removed and destroyed.
• In tobacco nurseries, spray chlorpyriphos 20 EC at 0.05% (20 ml in 10 L of water) at 30 and 40 days after germination. Final spray should be given before pulling out seedlings.
• In planted crop spray cholrpyriphos 20 EC 1.0 L in 500 - 800 L of water per ha at 20 and 30 days after planting.
• After completion of harvest, uproot and burn the stem borer affected plants to prevent carry over of the past to the next season.