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Maruca vitrata (Fabricius), commonly known as legume pod borer, is a serious pest in pulses affecting the yield. Liberal use of chemical insecticides to control has resulted in diverse array of insect detoxification enzymes produced by the pest to metabolize these toxic chemicals and develop resistance. Here, we studied the gut hydrolytic enzymes of M. vitrata up on its field exposure to different insecticides in order to have an idea about level of adaptation. Among the larval samples collected from different pulses, the maximum protein content of 547.14 mg was recorded per g of gut sample of legume pod borer, M. vitrata collected from green gram. Total trypsin activity was insignificant in gut samples of larvae collected from different samples. The total chymotrypsin and aminopeptidase activities were found maximum in cowpea of 0.5655 and 0.1184 mM/mL/min/g, respectively. Whereas, the maximum GST activity in lablab populations of M. vitrata (2.3335 mM/mL/min/g). The specific activity of trypsin was maximum in Maruca larval populations from lablab (0.0050 nM/mL/min/mg of protein) and red gram or pigeonpea (0.0049 nM/mL/min/mg of protein) and chymotrypsin activity in cowpea (0.0098 nM/mL/min/mg of protein). The larval samples collected from lablab (0.0052 nM/mL/min/mg of protein) and cowpea (0.0037 nM/mL/min/mg of protein) showed the maximum specific activity of aminopeptidase. Maximum specific GST activity of 0.0325 and 0.0294 nM/mL/min/mg of protein was recorded in larvae collected from lablab and red gram, respectively. Larval samples from black gram ranked the last with respect to the activity of gut enzymes. [ABSTRACT FROM AUTHOR]

Legume pod borer, Maruca vitrata Geyer is one of the serious pests occurring during flowering and pod formation stage of pigeonpea. Relative abundance of M. vitrata studied in pigeonpea variety, CORG 7 during Kharif and Rabi seasons of 2011 and 2012 at Department of Pulses, TNAU, Coimbatore revealed that in 2011, the first peak incidence was during 34th SMW (IV week of August) and 36th (I week of September) SMW as 4.44 and 3.68 webbings/ plant respectively followed by the second peak during 50 (II week of December) and 52nd (IV week of December) SMWs as 9.38 and 5.72 webbings per plant respectively. In 2012, on 50 and 52nd SMWs (II and IV weeks of December) the peak incidence of 6.21 and 5.10 webbings per plant were recorded respectively. The larval incidence showed a significant negative correlation with maximum temperature (r=0.455*), sunshine hours (r=0.382*) and evaporation (r=402*) and positive correlation with minimum relative humidity (RH) (r=0.399*) and rainfall (r=0.463*). Regression analysis showed all abiotic factors together determine the variation in Maruca damage by 61.4 per cent (R2 = 0.614). [ABSTRACT FROM AUTHOR]