STUDIES ON THE INSECT PEST COMPLEX OF MARIGOLD (Tagetes sp.) WITH SPECIAL REFERENCE TO THRIPS CALIOTHRIPS INDICUS BAGNALL (THYSANOPTERA: THRIPIDAE)
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Date
1999
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University of Agricultural Sciences, Dharwad
Abstract
Investigations on various aspects covering pest complex on marigold, survey and status of insect pests, seasonal incidence of insects pests, biology of thrips (Caliothrips indicus Bagnall), screening different varieties o f marigold and evaluation of synthetic insecticides and neem products was under taken at the Department of Agricultural Entomology, Agriculture College and Regional Research Station, Raichur, Karnataka during 1997-98. Studies on the surveillance o f various insects pests on marigold revealed five insects belonging to lepidopterist, 12 insects from hemiptera, 12 insects from coleoptera and 10 insects belonging to orthoptera as major, minor or as negligible insect pest at Raichur. Roving survey results revealed that the thrips {Caliothrips indicus Bagnall) incidence on marigold was noticed in all the three districts (Viz., Bidar, Gulbarga and Raichur). The thrips incidence was maximum (7.73 / leaf ) during vegetative stage of marigold at Raichur. The jassids and defoliators (T /- , Helicoverpa armigera Hb. Spodoptera litura F. , ash weevil and grass hopper) were also recorded in all the three districts. Peak incidence of thrips and H. armigera was recorded in all the three districts surveyed. Maximum incidence of thrips and H. armigera was recorded at Raichur and Bidar districts respectively during flowering stage of mangold. The studies on seasonal incidence o f pests of marigold revealed the peak appearance of the thrips between January and May, jassids between October and November and H. armigera during December. To obtain higher flower yield in mangold August, September and October months plantings were found to be suitable. The total life cycle of thrips, C. indicus occupied an average o f 16.80 3.24 days from opposition to adult emergence on marigold and it was 17.90 3.60 days on groundnut. Marigold genotypes screened against several pests, revealed that dwarf red Dharwad, Crimson red tall and Red tall marigold registerd the lower pest population. However, French dwarf marigold was highly susceptible to thrips and H. armigera. Among the twelve synthetic and botanical insecticides tested monocrotophos, dimethpate, acephate, fenvalerate and spinosad were found to be superior to the rest in reducing the sucking pests and H. armigera incidence. Higher yields were obtained from inonocrotophos treated plot followed by dimethoate.
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No . of references 66