Standardization of release rate of Trichogramma chilonis (Ishii) in bio-intensive management of Chilo partellus (Swinhoe) in fodder maize

Abstract

The early season attack of Chilo partellus, in kharif sown fodder maize inflicts appreciable losses, if unchecked. Biointensive management with the use of egg parasitoid Trichogramma chilonis Ishii in fodder maize through different doses and release rate was standardized. The results of the trials from two years showed that damage parameters like Leaf Injury (LI), recorded three weeks after parasitoid release from 0.25-6.00 per cent across different treatments whereas in untreated control it was 6.50-13.25 %, respectively. Similarly the observations on percent DH patterns in different treatments varied from 0.62-3.75 % as compared to control (5.50-9.0 %). Furthermore, the per cent reduction in damage was substantially low with the second inundative release of the parasitoid than plots receiving a single release of bio-agent at a given dose. The proportion of DH recorded at three weeks after release was significantly lower (1.0 and 0.62%) in plots with t-cards @ 125,000 parasitized eggs in two releases as compared with other treatments. Additionally the green fodder yield obtained in promising treatment was statistically superior (445 q ha^-1) to 392 q ha^-1 GFY as recorded in the untreated control and other lower dose treatments except the plots receiving the highest dose of parasitoid release (450q ha^-1). Thus the results suggested that field release of T. chilonis @ 125,000 parasitoids per hectare in two releases helps in substantial reduction of C. partellus inflicted damage with high economic returns.