SEASONAL INFESTATION, DAMAGE INCIDENCE AND MANAGEMENT OF MANGO LEAF CUTTING WEEVIL DEPORAUS MARGINATUS (COLEOPTERA: CURCULIONIDAE)

Abstract

The experiment was conducted to evaluate the seasonal infestation, damage incidence and management of mango leaf cutting weevil, Deporaus marginatus Pascoe in mango orchard of HSTU campus, Dinajpur during October 2016 to September 2017. For seasonal infestation and damage incidence, nine mango varieties namely, Amropali, Harivanga, Mallika, Surjapuri, Gopalvog, Langra, Fazli, Ashwina and Guti were used to conduct the experiment. Result showed that all the varieties were attracted to D. marginatus but Surjapuri showed the highest susceptibility. The highest percent infestation was found in Surjapuri (52.60%), and the lowest in Ashwina (33.40%). Pest incidence in regards to the month, the highest infestation was found in the month of August (77.47%) at surjapuri variety and the lowest was found in February (7.860%) at Mallika. There was no leaf infestation were found in the month of December and January in all the variety used in the study. Six indigenous weed extracts namely, black nightshade (Solanum nigrum), wild tobacco (Nicotiana plumbaginifolia), common Leucas (Leucus aspera), lantana (Lantana camara), goatweed (Ageratum conyzoides) and raan tulas (Croton sparsiflorus) were used to evaluate the insecticidal toxicity against mango leaf cutting weevil in the laboratory conditions. Methanol solvent was used to prepare the extracts and 3 concentrations (1.25, 2.5, and 5.0 %) along with control the highest toxicity effect (78.33 %) was found in rann tulas weed extract at 5.0 % concentation whereas black nightshade weed extract showed the lowest toxicity effect (10.83 %) at 1.25 % concentration. On the basis of weevil mortality, the order of the toxicity of the plant extracts were found as rann tulas > wild tobacco > Lantana camara > goat weed > leucas > black nightshade. Mortality percentages were directly proportional to different concentration level and hours after treatments. The lowest LD50 values (14.12, 0.36 and 0.13 mg/cm2 at 24, 48 and 72 HATs) of rann tulas weed extract indicated that the highest toxicity effects against mango leaf cutting weevil.