Influence of different levels of temperature and relative humidity on the speed of development, survival and fecundity of Macropes excavatus Distant (Hemiptera: Lygaeidae)

Atwal, A.S.; Singh, S.

Indian Journal of Entomology 33(2): 166-171


ISSN/ISBN: 0367-8288
Accession: 000116832

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Laboratory studies were carried out in the Indian Punjab on the effect of temperature and relative humidity on the hygaeid cavelerius (Macropes) excavatus (Dist.), a pest of sugar-cane. At 20, 25 and 30 deg C, respectively, the egg stage lasted 33.1, 17.2 and 12 days, viability being 56.7, 65.2 and 71%, and nymphal development took 62.5, 43.4 and 33.5 days, survival being 38.6, 52.1 and 56.7%. At 35 deg C, eggs and nymphs in the first three instars could not survive and the preoviposition and oviposition periods and length of life decreased. The optimum temperature for development of the immature stages and for female fecundity was 30 deg C. For all three temperatures together the egg stage lasted 19.5 days at 90% R.H. and 22.2 days at 40% R.H., and the development periods of nymphs in the five instars were, respectively 10.5, 6.7, 8.2, 7.5 and 9 days at 90% R.H. and 12, 7.4, 9.2, 8.2 and 9.9 days at 40% R.H. Nymphal survival was greatest at 90% R.H. A combination of 30 deg C and 90% R.H. was the most favourable for nymphal development. Although females became sexually mature earlier at 35 deg C than at lower temperatures, the oviposition period was 5.5 days at 35 deg C and 22.6 days at 30 deg C. Females laid most eggs (166) at 30 deg C. The low humidity and high temperature (35 deg C or above) encountered in the State during May-June appeared to be unfavourable for development of eggs and young nymphs, whereas the higher humidity (70-90% R.H.) and moderate temperature (30 deg C) found during the monsoon period from July to September resulted in the largest populations (12.4 nymphs/plant) occurring during August.