Effect of aqueous plant extracts on tea red spider mite, Oligonychus coffeae, Nietner (Tetranychidae: Acarina) and Stethorus gilvifrons Mulsant
AbstractFour aqueous plant extracts (APEs) of Acorus calamus (L), Xanthium strumarium (L), Polygonum hydropiper (L) and Clerodendron infortunatum (Gaertn) were evaluated under both laboratory and field
conditions at 2.5, 5.0 and 10.0% (w/v) concentrations against tea red spider mite, Oligonychus coffeae (Nietner). Also, the impact of APEs on survival and feeding of Stethorus gilvifrons, a potent coccinellid
predator of red spider mite was studied. Parameters assessed were ovicidal activity and acaricidal activity in case of red spider mite, and feeding activity and adult mortality for the coccinellid. Strong
ovicidal action was observed with X. strumarium (87.09%) and A. calamus (70.62%) whereas least action in P. hydropiper (30.86%) and C. infortunatum (20.58%). All the APEs showed > 50% mortality of red
spider mite at higher concentrations (5 and 10%) under laboratory conditions. Field evaluation of APEs recorded 46.9 – 81.8% mite reduction at 5.0% and 64.7 – 100.0% at 10.0% concentration. More acaricidal activity was noticed in C. infortunatum and X. strumarium under field condition. The APEs, even at higher concentration (10%), caused no mortality to the adults of S. gilvifrons for 14 days, and no
significant change in feeding after 24 h in comparison with untreated control. Crude plant extracts of A. calamus, X. strumarium, P. hydropiper and C. infortunatum can effectively be utilized as safer
phytopesticidal products in both organic and inorganic tea estates as one of the potent tools in integrated mite management.