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Isotima javensis is a solitary ecto parasitoid of the sugarcane top borer, S. exceptalis. It attacks the prepupal stage and deposits an egg either on the prepupa or near its vicinity. The extent of parasitisation was observed 2.12%, 4.28%, 7.14%, 5.88% and 5.23 % in I, II, III, IV and V broods of top borer, respectively. The contribution of mortality of pupae of the top borer by parasitisation is high in III and IV broods (Aug-Oct), the time when the brood infestation remains generally very high. The maximum female ratio (59.72%) was observed in III brood of parasitisation followed by 55.20 % in IV brood. In I and II broods, however more or less equal number of males and females can be observed in the field. Equality in the sex ratio at this time ensures fertilisation of almost all the females for retaining the vigour and vitality of the species. The absence of unfertilized parasites naturally removes the chances of parthenogenetic reproduction and thus the number of females gradually rises in the succeeding season. It is concluded that there are several attributes of parasitoid i.e. specific parasite of top borer; its life cycle is much shorter than its host; active throughout the period of activity of the host and even it hibernates under north Indian conditions which make it a good biocontrol agent. It is suggested that parasitoid may be exploited in biological control programme, more detailed study is required for mass multiplication in the laboratory on an alternate host, release technique and survival in the sugarcane field.
How to Cite
Baitha, A., Tripathi, G., Lal, R., & Nigam, R. (2017). A note on parasitisation of top borer by Isotima javensis Rohwer (Hymenoptera: Ichneumonidae). International Journal of Agricultural Invention, 2(01), 82-84. https://doi.org/10.46492/IJAI/2017.2.1.18
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