Field population dynamics of Trichogramma chilonis on eggs of Sugarcane internode borer

The egg parasitisation on internode borer ranged from 34.4 to 62.1% during 2006 to 2014. The extent of parasitisation by Trichogramma chilonis is differing with regions and with season in same region. The mean number of parasitized eggs of internode borer was varied from 19.87 to 33.77. Adult emergence from parasitized egg masses varied from 68.4 to 150.6%. During 2009, 2011, 2012 and 2014; emergence percentage was 106.7, 102.5, 110.3 and 150.6, respectively. Results showed that during these periods, more than one adult emerged from each parasitized eggs. The urge for oviposition was so great in this parasite that it laid two or three eggs in a host during a single insertion of the ovipositor of the parasite. The per cent female emergence was observed as 97.9 in 2009 followed by 94.6 (2012), 89.2 (2013), 86.2 (2007), 82.4 (2010), 80.2 (2008), 76.6 (2011 & 2014) and lowest 59.4 in 2006. The field-collected eggs showed preponderance of female ratios. It is concluded that populations of T. chilonis was more active during August-September with highest parasitisation and more female biased ratio that are useful for minimize the incidence of INB.