Factors influencing thrips abundance and distribution on rose flowers in central India.
The factors affecting thrips (Scirtothrips dorsalis and Thrips flavus) abundance and distribution on rose flowers in central India were investigated in trials in 2 fields in Maharashtra, India from 1996 to 1998. In the first field, cv. Gladiator was used, while in the second, cultivars Gladiator, Folklore and Landora were used. Insecticides were sprayed 3 times: monocrotophos 0.05% + carbendazim 0.2% at 700 l/ha during 13 October 1996; monocrotophos 0.05% + cypermethrin 0.006% at 500 l/ha during 30 March 1997; and monocrotophos 0.05% + cypermethrin 0.01% at 500 l/ha during 20 May 1997. Thrip population levels were high during January-March and low during May-July. The percentage of infested flowers varied in the range 14-88, 28-95 and 37-52% in 1996, 1997 and 1998, respectively. Maximum and minimum temperatures, and insecticide applications had a significantly negative effect on infestation and thrip numbers. The thrip number significantly varied with the level of flower infestation, flower colour, compactness, size and petal position. Thrips preferred loose, small-sized and red-orange coloured flowers.