Species, Population Density and Biology of Mites Associated with Cotton in Thailand

Abstract

Species, population density and biology of mites associated with cotton grown in Thailand were carried out during October 1998-November 2001. Mite specimens were collected from the infested cotton leaves grown in different parts of 13 provinces of Thailand. They wee then mounted on the slides and identifies. Results from the investigation of mite specimens revealed the occurrences of 25 species of mites asociated with cotton. Among which 10 of them wee regarded as pests, the rests were regarded as predators. Tetranychus kanzawai kishida is the most important pest and whide spread on cotton. Amblyseius asiaticus Evans and A. longispinosus (Evans) are the most abundant and important species of predatory mites found in cotton fields. Results from the biological study of T. kanzawai, the most important mite pest of cotton, revealed the completion of development from eggs to adults of the male and fermale mites pest of cotton, revealed the completion of development from eggs to adults of the male and fermale mites as 8.47 +- 0.72 and 8.14 +- 0.38 days respectively. Each mated female could lay at the average of 13.44 +- 7.34 eggs throughout her adult life. The unmated female produced only male progenies while the mated frmale produced both male and female progenies at the ratio of 1 : 7
Studies were also carried on the species and population density of mites on Srisamrong 60 cotton variety throughout the growing season of 20001 at Nakhon Sawan field Crops Research Center. The results indicated high density of Polyphagotarsonemus latus (Banks) throughout the growing season but the highest population was observed in October related to the density of predatory mites, A. asiaticus. The research was then conducted on the feeding ability of this predatory mite on their coexisting prey, P. latus. The results showed that A. asiaticus could prey on P. latus at the average of 9.33 +- 3.52 adults/day.