YADAV, D. N.Patel, Rajesh K.2018-05-172018-05-171991http://krishikosh.egranth.ac.in/handle/1/5810046452Effect of intercropping marigold on the infestation of Heliothis armigera Hubner and its natural enemies in seed crop of tobacco and tomato was studied during 1990-91 season at the Anand Campus of Gujarat Agricultural University. H.armigera Hubner preferred marigold to tobacco for oviposition. Opened flowers were preferred over buds. Disc-floret type of flowers received greater number of eggs, than ray-floret type. In tobacco, buds are preferred for oviposition. Different combinations of marigold viz., 1 row of marigold and 1 row of tobacco, 1 row of marigold and 2 rows of tobacco, 1 row of marigold and 3 rows of tobacco, 2 rows of marigold and 2 rows of tobacco, 2 rows of marigold and 1 rows of tobacco, 2 rows of marigold and 6 rows of tobacco and random i.e. growing marigold (3 10% plants,were effective in attracting Heliothis moths to lay significantly greater number of eggs than tobacco. Similarly, these combinations were effective in reducing larval infestation of Heliothis except in 1 : 1 and 1 : 2. Heliothis laid significantly higher number of eggs in the third and fourth week of November suggesting that temperature 17.3 to 30.4°C and 80% RH were conducive for oviposition. Similarly significantly higher number of larvae were found during first and second week of December and second week of January. Temperatures ranging from 11.8 to 27.3°C and 80.5% RH appear to favour the development of the Iarvae. Data on capsule damage showed that lowest damage was observed in 2 : 4 combination followed by 2 : 6, 1 : 3, 1 : 2, randomly grown marigold, 1 : 1, tobacco distant control and 2 : 2. Highest seed yield was recorded in 2 : 6 combination (1351.12 kg/ha). Intercropping marigold did not affect the activity of the mirid predator, Nesidiocoris tenius R. It helped in the occurrence of Trichogramma chilonis Ishii to a little extent. It was also found reducing root knot nematode, Meloidogyne javanica population to some extent. Disc floret marigold were more often visited by honey bee. Apisindica (3.37 bees/plant) as compared to ray floret (0.14 bees/plant). Further yellow disc floret attracted more number of bees/plant. Studies in tomato revealed that, tomato in presence of marigold received significantly lesser number of eggs than control. Consequently significantly lesser number of larvae were observed in experiments) tomato. On the other hand, control plot had higher larval count.enAGRICULTURAL ENTOMOLOGY, AGRICULTUREIMPACTThesis