Studies on the Seasonal Activity of Shootfly Through Fish Meal Trap

Seasonal incidence of shootfly in terms of egg load and dead heart formation on sorghum revealed that the pest was active through out the study period of four months starting from 27th to 44th standard week. Attempts were also made to establish relationship between egg load and dead hearts with weather parameters of one, two, three and four weeks lead time (prior) and same week of the observations. In all the aforesaid correlated weeks, the combined weather parameters of maximum temperature with afternoon and morning relative humidity were highly significant and negatively correlated with egg load and dead hearts. Whereas, the morning and afternoon R.H., minimum temperature and after noon RH together exerted highly significant positive relationship with egg load and dead hearts. However, the same week weather parameters influenced more on egg load (54%) and dead hearts (44.7%). Studies on the shootfly catches in fish meal trap revealed that, highest peak catch of 488 flies/trap was recorded during 35th standard week. On an average 92.6 and 7.2% females and males were trapped, respectively. The reproductive status of females revealed 39.3, 47.9 and 13.2% as gravid, spent and freshly emerged adults, respectively. Trap catches established positive relationship with egg load and dead hearts in all the correlated weeks. The egg load of one and two week after the catch was highly significant. Similarly the dead heart formation in one, two and three weeks after the catch was also positive with highly significant correlations. Effect of weather parameters on trap catches revealed that, the maximum and minimum temperature and rainfall had negative relationships. Maximum temperature at two and three weeks prior to trap catch had highly significant positive correlation, whereas the afternoon R.H. at two weeks before trap catch had positive significant correlation.