Author(s): Deka MK, Saikia GK
Clerodendron inerme and Lantana camara extracts at 10.0, 8.0, 6.0, 4.0 and 2.0% concentrations were investigated in the laboratory against tea mosquito bug, Helopeltis theivora. The extracts exhibited significant effect on growth regulating properties such as feeding, nymphal and adult longevity, weight, mortality, adult emergence and fecundity The number of spots produced by a 4th instar nymph within 72 h varies from 385.00 395.75 and the same was reduced to 40.50±3.10 to 65.25±3.50 and 55.25±5.35 to 80.00±3.98 at 10.0 to 2.0% extracts of C. inerme and L. camara, respectively. Both the plant extracts enlengthened the duration of nymphal instars of the pest significantly. However, C. inerme enlengthened the duration of instar more significantly (4.00–4.75 d) than L. camara (3.19-.4.49 d). The per cent mortality of nymph varied from (21.50–30.12%) of C. inerme and (10.50–26.40%) of L. camara at 2.0–10.0%, respectively. The adult emergence (25.50–39.75 male and 26.30–40.15% female) from these treated nymphs also reduced significantly. Likewise, the extracts showed strong antifeedant effect (28.65–36.35 and 53.85 to 62.35 spots) in C. inerme and L. camara at 2.010.0% extracts respectively to the adults. The weight of both male and female adult reduced to 2.40–3.73 and 2.62–3.75 mg and 4.21- 5.49 and 4.36–5.64 mg by C. inerme and L. camara, respectively. Likewise the adult longevity was also reduced by both the extracts. The treated female also laid very few eggs (38.25–57.50) as against 115.25–116.13 eggs in untreated female.