Abstract
A research work on bioecology and management of pod borer, Helicoverpa armigera
(Hubner) in chickpea was conducted in the laboratory and field of Regional Agricultural
Research Station, Bangladesh Agricultural Research Institute, Ishurdi, Pabna, Bangladesh
during October 2003 to April 2006. Females laid 680-1620 eggs singly or 2-6 eggs in a
cluster at night during 3.45 days of oviposition period. The incubation period of egg
ranged from 2-4 days and the larva passed through six instars. The duration of 1st, 2hd, 3rd
,4th, 5th and 6th instar larvae were 2-4, 2-4, 2-3, 1-3, 1-3 and 1-2 days, respectively. The
length and breadth of full grown larvae ranged from 25.0-36.0 mm and 4.0-5.5 mm,
respectively. A period of 10-15 and 9-14 days were required to complete larval and pupal
stages, respectively. The longevity of male and female ranged from 3-5 and 4-9 days,
respectively. The male and female completed their life span (egg to death of adult)
between 28-33 days and 29-36 days, respectively. The pest appeared in the chickpea field
between second and last week of January, irrespective of sowing dates. Pod borer damage
was higher in early (October 15 to November 01) and late (December 15 to January 15)
sown crops than the mid sown (November 08 to November 30) crops. For getting higher
yield with low pod borer damage optimum sowing date ranged from November 08 to
November 30 and the best was November 15. In screening of varieties/lines of chickpea
against pod borer damage, it appeared that physiomorphological traits like erect growth
habit, thicker pod wall, bigger pod size, and ribbed and tuberculated seeds might be
attributing in resistance to pod borer. Among the tested varieties/lines, three lines ICCV95138, ICCV-96020 and ICCV-98939 were found most promising in respect of pod borer
resistance and yield potentiality. Of them, the line ICCV-95138 was the best one.
Application of low to moderate dose levels of NPK fertilizer reduced pod borer damage
with higher yield. The manurial combination 40-20-20 kg NPK/ha was found effective
and most economic dose in chickpea cultivation followed by 20-40-20 kg NPK/ha.
Intercropping in chickpea with coriander, linseed, mustard, wheat and safflower reduced
pod borer damage significantly. Pod borer damage reduction by intercrops ranged 44.76-
60.41%. Mustard was the most profitable intercrop in protecting pod borer damage in
chickpea ensuring higher yield and return. Cypermethrin and HNPV (Helicoverpa
nuclear polyhedrosis viruses) were found equally the most effective insecticide in
reducing pod borer damage in chickpea. HNPV application provided higher benefit cost
ratio than cypermethrin because of higher cost of cypermethrin. An attempt was made to
accommodate all the best treatment with a view to developing an integrated pest
management approach. The most economic IPM module for pod borer management was
promising line of chickpea (ICCV-95138) intercropped with mustard sown on November
15. To get best protection against pod borer, the most effective IPM module was sowing
chickpea (ICCV-95138) on November 15 and first spray with HNPV @ 500 LE(Larval
equivalent)/ha just at 100% plants pod formation stage and second spray with
cypermethrin @ 1 ml/l after 7 days of first spray. The former IPM approach may be
useful where there is no serious problem of pod borer, while the latter IPM approach may
be useful where severe pod borer outbreak occurs.