Effect of temperature on different stages of Romanomermis iyengari, a mermithid nematode parasite of mosquitoes.
The effect of temperature (20 degrees-35 degrees C) on different stages of Romanomermis iyengari was studied. In embryonic development, the single-cell stage eggs developed into mature eggs in 4.5-6.5 days at 25-35 degrees C but, required 9.5 days at 20 degrees C. Complete hatching occurred in 7 and 9 days after egg-laying at 35 and 30 degrees C, respectively. At 25 and 20 degrees C, 85-96% of the eggs did not hatch even by 30th day. Loss of infectivity and death of the preparasites occurred faster at higher temperatures. The 50% survival durations of preparasites at 20 and 35 degrees C were 105.8 and 10.6 hr respectively. They retained 50% infectivity up to 69.7 and 30.3 hr. The duration of the parasitic phase increased as temperature decreased. Low temperature favoured production of a higher proportion of females which were also larger in size. The maximum time taken for the juveniles to become adults was 14 days at 20 degrees C and the minimum was 9 days at 35 degrees C. Oviposition began earlier at higher temperature than at lower temperature. However, its fecundic period was shorter at 20 degrees C than at 35 degrees C indicating enhanced rate of oviposition at 20 degrees C. Fecundity was adversely affected at 20 degrees C and 35 degrees C. It is shown that the temperature range of 25 degrees-30 degrees C favours optimum development of R. iyengari.
Vector Control Research Centre (Indian Council of Medical Research), Indira Nagar, Pondicherry, India.
K P
KP
Paily
K
K
Balaraman
D000818:Animals; D009033:Culicidae / Q000469:parasitology*; D005260:Female; D008297:Male; D008632:Mermithoidea / Q000254:growth & development / Q000502:physiology*; D013696:Temperature