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Evaluation of neem, Azadirachta indica, with and without water management, for the control of culicine mosquito larvae in rice‐fields
Author(s) -
RAO D. R.,
REUBEN R.,
VENUGOPAL M. S.,
NAGASAMPAGI B. A.,
SCHMUTTERER H.
Publication year - 1992
Publication title -
medical and veterinary entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 82
eISSN - 1365-2915
pISSN - 0269-283X
DOI - 10.1111/j.1365-2915.1992.tb00627.x
Subject(s) - azadirachta , azadirachtin , neem oil , biology , meliaceae , toxicology , instar , bioassay , neem cake , veterinary medicine , culex tritaeniorhynchus , horticulture , larva , botany , agronomy , pesticide , virus , japanese encephalitis , ecology , medicine , vermicompost , encephalitis , virology , nutrient
Applications of neem, Azadirachta indica (Meliaceae), to rice‐fields were evaluated with the dual objective of controlling the culicine mosquito vectors of Japanese encephalitis virus (JEV) and enhancing the grain yield. Since crude neem products deteriorate under improper storage conditions, a laboratory bioassay was developed to screen neem cake powder against mosquito larvae, Cule.x quinquefasciatus. Only samples of neem giving over 90% bioassay mortality were used in field trials. When good quality neem cake powder was applied at the dose of 500 kg/ha, either alone or coated over urea, there was a striking reduction in the abundance of late instar culicine larvae and pupae. Only fourteen pupae were obtained over a period of 13 weeks in neem cake powder treated plots, and four in those treated with neem coated urea, compared with 101 in control plots. Both treatments were significantly less than the control, but on par with one another. In another field trial, neem cake coated urea was tested at 500 and 250kg neem/ha in combination with water management practices. No reduction in efficacy was noted at the lower dose. Larval abundance in plots under water management alone did not differ significantly from the controls, but was significantly reduced when water management was combined with neem products. Two stable formulations, ‘Neemrich‐I’ (lipid rich) and ‘Neemrich‐H’ (azadirachtin rich), also gave good suppression of immature culicines. All the treatments with neem also gave higher grain yield than the control. Therefore, it is feasible to develop an acceptable package for community use, particularly as the Agricultural Department already recommends the use of both water management and neem cake coated urea to farmers.