Suneet Pandher

Selection of housekeeping genes and demonstration of RNAi in cotton leafhopper, Amrasca biguttula biguttula (Ishida)

Amrasca biguttula biguttula (Ishida) commonly known as cotton leafhopper is a severe pest of cotton and okra. Not much is known on this insect at molecular level due to lack of genomic and transcriptomic data. To prepare for functional genomic studies in this insect, we evaluated 15 common housekeeping genes (Tub, B-Tub, EF alpha, GADPH, UbiCF, RP13, Ubiq, G3PD, VATPase, Actin, 18s, 28s, TATA, ETF, SOD and Cytolytic actin) during different developmental stages and under starvation stress. We selected early (1st and 2nd), late (3rd and 4th) stage nymphs and adults for identification of stable housekeeping genes using geNorm, NormFinder, BestKeeper and RefFinder software. Based on the different algorithms, RP13 and VATPase are identified as the most suitable reference genes for quantification of gene expression by reverse transcriptase quantitative PCR (RT-qPCR). Based on RefFinder which comprehended the results of three algorithms, RP13 in adults, Tubulin (Tub) in late nymphs, 28S in early nymph and UbiCF under starvation stress were identified as the most stable genes. We also developed methods for feeding double-stranded RNA (dsRNA) incorporated in the diet. Feeding dsRNA targeting Snf7, IAP, AQP1, and VATPase caused 56.17–77.12% knockdown of targeted genes compared to control and 16 to 48% mortality of treated insects when compared to control.

Reference Gene Selection in Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) and Their Normalization Impact on Gene Expression in RNAi Studies

Abstract Phenacoccus solenopsis, the cotton mealybug (Hemiptera: Pseudococcidae), is one of the major cotton pests in India. Scanty information is available on molecular studies in this insect due to limited genomic or transcriptomic sequence data. With advancement in sequencing technology, enormous genomic and sequencing data are being generated, and RNAi studies are being undertaken in insects, which require reverse transcription quantitative polymerase chain reaction evaluation. These gene expression studies require normalization of mRNA levels with reference genes to account for sample variability. To supplement the molecular studies in this insect, candidate reference genes were identified and evaluated for their expression stability across various developmental stages and starvation stress. Fourteen candidate reference genes including several commonly used ones were investigated across five different stages and under starvation stress using four different statistical algorithms (NormFinder, genNorm, BestKeeper, and RefFinder). Based on this analysis, GST (third, fourth, and adult stage), Actin (Crawler, second instar), TFIID (starvation stress), SDHA, and 28s were identified as best reference genes for expression studies in mealybug.

Information Communication Technology for Extension: A Mobile Phone Based Voice Call System for Dissemination of Cotton Production Technologies

ABSTRACT Dissemination of newer crop production technologies among growers is the major bottleneck in the existing extension system. This study proposes an innovative method for dissemination of cotton cultivation technologies through mobile phones. The voice advisories on different aspects of cotton cultivation were sent to mobile phones of growers, as and when required in the field. Feedback from growers revealed it as a highly acceptable extension technique, which helped them to make crucial time-specific decisions for crop management. The system has the potential to reach and benefit each and every grower at a very low cost compared to conventional training and visit extension system.

Persistence of carbaryl and its risk assessment through consumption of treated grapes

The average initial deposits of carbaryl were observed to be 1.4 and 3.1 mg kg−1, respectively, following four applications of the insecticide at 4.95 and 9.9 kg active ingredient per hectare. Residues of carbaryl dissipated below its limit of quantification of 50 µg kg−1 after 7 and 10 days at single and double the application dosage, respectively. The half-life values (t 1/2) of carbaryl were worked out to be 1.3 and 0.7 days, respectively, at single and double dosages. The acceptable daily intake (ADI) for carbaryl has been fixed at 8 µg kg−1 body weight per day. Keeping in view the residues of carbaryl observed one day after the last application, a child of 10 kg and an adult of 60 kg will have an intake of 77 and 154 µg carbaryl after consumption of 100 and 200 g grapes, in comparison to its ADI of 80 and 480 µg; thus, no health risk is to be expected. Therefore, a waiting period of 1 day has been suggested for the safe consumption of carbaryl-treated grapes to avoid any health hazards.