Project Directorate of Biological Control, H.A. Farm Post, P.B. No. 2491, Bellary Road, Bangalore - 560 024, Karnataka, India.
The influence of temperature on the sex ratio of Telenomus sp. was studied by exposing the eggs of Spodoptera litura for varying periods (2, 4, 6, 12, 24 and 48 hours) at different temperatures (27 – 36°C). Freshly laid eggs (0–2 hours old) were offered to the parasitoid in the ratio of 5:1 at the varying temperatures and exposure periods. The ratio of female to male was higher (1.92:1 to 2.58:1) at temperatures of 27–32°C, irrespective of the exposure time of the eggs to the parasitoid., while temperatures > 34°C altered the sex ratio in favour of males (1:1.3 to 1:1.75). Temperature of 27°C with an exposure period of 24 hours provided for an optimum sex ratio skewed towards the females (2.58:1). The shift in the sex ratio towards males at higher temperatures had a negative impact on the perpetuation of the parasitoid.
