Parasitoid complex of legume pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae) on different pulses

The spotted pod borer, Maruca vitrata Fabricius is an important herbivore of major pulses and vegetable legumes in India and the chemical pesticides are major contributors for its management. In order to have an idea on other alternative management tools, the present studies were carried out on the availability of parasitoids and its genetic variation. Totally, four larval parasitoids viz., Bassus sp., Trathala flavoorbitalis Cameron, Phanerotoma hendecasisella Cameron and an undetermined Braconid wasp were recorded on M. vitrata larva. The occurrence of P. hendecasisella was reported for the first time from Tamil Nadu, India. The Bassus sp. was found to be dominant with the parasitism of 3.0 to 12.7% in different pulses and total parasitism of four parasitoids was maximum in pigeonpea (16.1 %). Total parasitism had a positive relationship with number of webbings on cowpea. The larval parasitoids Bassus sp. and braconid wasp (undetermined) yielded specific fragments (~800 bp) with mitochondrial COI primer. Presence of Wolbachia was confirmed in all four larval parasitoids with the amplicons size between 600 and 650 bp. Present study clearly indicated the close proximity of Bassus sp. on M. vitrata than other parasitoids studied. Hence, it gives way for further insights on suitability, mass culturing and development for sustainable management of this insect pest.

Spatial genetic variation in South Indian larval populations of legume pod borer, Maruca vitrata Geyer (Lepidoptera: Crambidae)

The Legume pod borer Maruca vitrata (Fabricius) is a serious pest in most common pulses affecting their yield. In the present investigation, genetic diversity among larval population of Maruca vitrata from five locations of India was assessed using 23 RAPD primes and 6 SSR primers. RAPD primers produced 364 (98.9% polymorphism) polymorphic alleles with the mean number of 18.2 alleles/primer while SSR primers produced 45 polymorphic alleles with 68% polymorphism. The mean number of alleles detected per primer ranged from 4 to 46 and 5 to 12 with RAPD and SSR primers, respectively in different larval samples. Dendrogram constructed using similarity index values for RAPD and SSR primers differentiated the larval samples. In all three types of Maruca larval samples, Polymorphism information content (PIC) value observed for RAPD primers ranged from 0.019 (OPC 08) to 0.375 (OPAF 12). Similarly, SSR primers showed PIC value of 0.061 (C32008E) to 0.781 (C3393E,1) irrespective of larval samples.

Variation in the gut hydrolytic enzymes of legume pod borer, Maruca vitrata (Fabricius) feeding on different pulses

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.

Microbial control of the invasive spiraling whitefly on cassava with entomopathogenic fungi

Abstract The entomopathogenic fungi Beauveria bassiana, Metarhizium anisopliae, Lecanicillium lecanii and Isaria fumosorosea were tested for their efficacy in managing the exotic spiraling whitefly Aleurodicus dispersus (Hemiptera, Aleyrodidae) on cassava (Manihot esculenta) during 2 seasons (2011-2012 and 2012-2013). The fungi I. fumosorosea and L. lecanii exhibited promising levels of control (> 70% mortality of the A. dispersus population). The percent mortality increased over time in both seasons. Application of I. fumosorosea was highly pathogenic to A. dispersus in both seasons compared to the other entomopathogenic fungi. Analysis of the percent mortality in both seasons revealed differences in efficacy between 3 and 15 days after treatment. The season also influenced the effects of the fungi on the A. dispersus population. Thus, entomopathogenic fungi have the potential to manage A. dispersus infestation of cassava.

Generation and screening of recombinant inbred lines of rice for yellow stemborer resistance.

Based on the results of studies on varietal screening, antixenosis (egg laying preference) and antibiosis (larval survival and adult emergence), rice varieties W1263 and CO43 were selected as resistant and susceptible parents, respectively, for yellow stemborer (YSB) infestation. A mapping population was developed using above parents following single seed descent method. Screening for YSB reaction in F1 and F2, generations under field and glasshouse conditions for both dead hearts and white ears, established the polygenic nature of inheritance for YSB resistance. Field screening for YSB resistance at F9 generation revealed the difference in the reactions among recombinant inbred lines (RILs) between vegetative and reproductive stages. The experiments under field and glasshouse screening of RILs for dead hearts showed significant positive association. However, the reaction was more towards susceptibility in glasshouse screening due to no choice test. Scoring of 250 RILs (F8) for various morphological traits showed wide range of variation indicating the suitability for QTL mapping.