Sex Ratio of Cryptopygus thermophilus in Rubber Plantations of Chengannur Thaluk of Alappuzha District, Kerala, India

Sex ratio of Cryptopygus thermophilus in Rubber plantation of Chengannur Thaluk, Alappuzha district, Kerala state, India, from June 2014 to August 2015 was studied.100 samples were randomly collected every month. Hand sorting and light funnel extraction was adopted to extract Cryptopygus thermophilus. Ovipositer of females and a small protuberance in the third ventral abdominal segment in male were taken in to consideration for sex identification. The study showed that the male female ratio is almost 11.5 in all these months. The Length range sex ratio observed showed that 0-1 cm range, males outnumbered females, but 2-3 cm range, females outnumbered males and above 5 cm length range, males were totally absent. In all these cases critical chi-square value was larger than the computed chi-square value with P greater than 0.01 indicating a deviation of the sex ratio from normal 11. Male survivor ship is high in lower length range and female survivor ship is more in upper length range in the studied habitat.