Post-Graduate School of Entomology, Fredrick Institute of Plant Protection and Toxicology, Padappai-601 301, Tamil Nadu (India).
The development of freshly laid and six-day old eggs of Eurybrachys tomentosa Fabr. was investigated at four different temperatures, viz., 0, 20, 28 and 42°C. Both types of eggs were allowed to incubate separately for 2, 4 and 6 days at four temperature regimes initially and then transferred at ambient temperature (28–32°C) till the emergence of first batch of nymphs. There was no significant variation in the incubation period when different batches of eggs of different oviposition timings were left to hatch at room temperature. But, when the freshly laid eggs were subjected to low temperatures (20°C, O°C) prior to allowing them to hatch at room temperature, the total incubation period was appreciably retarded, the variation being 20.5–32.2 days. In the earlier stage of embryonic development, however, the viability increased, being 82.75–96.55 when subjected to this treatment. With higher temperatures (3g°C, 42°C). the incubation period of both advanced and earlier stages of development was reduced (13–16.75 days). There was no significant variation in the incubation periods, considering the duration of exposure periods at different temperatures. The hatching percentage of the eggs in earlier stage of development was lessened (55.5–85.5%) but increased in the case of 6-day old eggs (80.25–95%).
