Biology of tetranychus urticae koch and seasonal incidence of mites infesting citrus
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Date
2014
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Punjab Agricultural University, Ludhiana
Abstract
The biology of two-spotted spider mite, Tetranychus urticae Koch and seasonal incidence of mites infesting citrus was studied during 2013-2014 at the Acarology Laboratory, Entomological Research Farm, Department of Entomology and New Orchard, Department of Fruit Science, Punjab Agricultural University, Ludhiana. Biological studies on T. urticae revealed that the mean incubation, larval, protonymphal and deutonymphal period was found to be 2.52, 2.74, 2.08, and 2.40 days, respectively. The pre-oviposition, oviposition and post-ovipostion period was 0.96, 1.78 and 6.40 days, respectively. The fecundity of 1.56 eggs/female and longevity of females (9.40 days) and males (6.71 days) was observed. The sex ratio was in favour of females (4.33:1). Studies on oviposition response of T. urticae on different citrus genotypes revealed that oviposition was found to be maximum on SL-4 and G-4 followed by BL-2 and G-4 genotypes and no egg laying was observed on SL-3, SL-7, G-7, BL-1, BL-3 and Tahiti lime. Feeding preference studies revealed that mites preferred KL-7 genotype the most, but had least preference for G-4 genotype. Observations on the seasonal incidence revealed that peak occurrence of Brevipalpus phoenicis was reported during 47th standard week (SW) (23.0 mites/leaf); Tetranychus urticae during 21st SW (6.25 mites/leaf), while Polyphagotarsonemus latus started occurring during November-December (47th to 25th SW). The population of Eutetranychus orientalis was observed during April-June (16th to 26th SW) as with increase in temperature there was increase in population of mites. The population of predatory mites viz. Tydeids, Phytoseiids and Cunaxids was observed throughout the year with peak incidence during 29th SW and 46th SW, respectively. Although the mite populations showed both negative and positive correlations with the various abiotic parameters, but statistically these were found to be non significant.
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Keywords
Citrus genotypes, Kinnow, two-spotted spider mite, tetranychus urticae