In vitro Assessment of Neonicotinoids and Pyrethroids against Tea Mosquito Bug, Helopeltis antonii Sign. (Hemiptera: Miridae) on Guava

The tea mosquito bug (TMB), Helopeltis antonii, is an emerging pest of horticultural crops, specially on guava and moringa. Insecticides are indispensable component for the management of insect pests. Exploration of new molecules with shortest waiting period may pave way for managing TMB in fruit and vegetable crops with nil/low residue. Until now there are no recommended insecticides available under Central Insecticides Board & Registration Committee (CIB&RC) against TMB on guava. In view of the above facts, new molecules with a low waiting period and are recommended by CIB&RC on tea, viz., Clothianidin 50% WDG, Thiacloprid 21.7% SC, Bifenthrin 10% EC, and Thiamethoxam 12.60% + Lambda-Cyhalothrin 9.5% ZC, were chosen and evaluated against TMB under in vitro condition. Clothianidin 50% WDG recorded the highest mortality of 100.00 per cent at 72 hours after treatment (HAT), and the lowest LC50 value (0.328 ppm, fiducial limits: 0.144-0.515 ppm) and LT50 value (10.49 h, fiducial limits: 5.444-14.551 h), followed by Thiamethoxam 12.60% + Lambda-Cyhalothrin 9.5% ZC, Thiacloprid 21.7% SC, and Bifenthrin 10% EC. The results showed that the Clothianidin 50% WDG and Thiamethoxam 12.60% + Lambda-Cyhalothrin 9.5% ZC, were highly effective, with the lowest LC50 and LT50 values. Since TMB occurs from new flushing to fruiting stage of guava, a minimum of two sprays are mandatory to have quality fruit yield. Hence, application of Clothianidin 50% WDG followed by Thiamethoxam 12.60% + Lambda-Cyhalothrin 9.5% ZC on need basis will help to reduce the impact of TMB on guava

Temperature Tolerance in the Five Field Strains of Trichogramma chilonis from Northern Districts of Tamil Nadu, India

The egg parasitoid, Trichogramma chilonis is a potential egg parasitoid in the agricultural ecosystem, reducing many lepidopteran pest incidences. The laboratory strains of T. chilonis was significantly inferior to the ecotypes collected from fields in their parasitisation potential and tolerance to temperature due to continuous exposure to temperature extremes in the field. Hence, a study was undertaken to evaluate the laboratory reared strain of T. chilonis with that of other ecotypes to identify a temperature tolerant ecotype for use in pest management programme. Five ecotypes of T. chilonis were collected from farmer's fields on sugarcane and citrus using sentinel egg technique by exposing egg cards of Corcyra cephalonica, mass reared on C. cephalonica for three successive generations and tested for their relative tolerance to temperature in comparison with the laboratory population. The emergence percentage of the parasitoid varied with the ecotypes tested and all the field collected ecotypes recorded increased emergence compared to the laboratory population. At 150 C, the emergence was significantly higher in Chitteri ecotype (83.44%) followed by Arungunam and Amirthapuram ecotype (78.65 and 75.57%). The performance of all the ecotypes were best at 200 C and Chitteri ecotype performed significantly better compared to other ecotypes and the laboratory population with an adult emergence of 95.66 per cent. It was followed by Arungunam ecotype (88.65%) at 200 C. While the laboratory population and other ecotypes failed to develop at 350 C, Chitteri and Arungunam ecotypes were able to develop with 9.66 and 7.25 per cent adult emergence from the parasitised eggs

Baseline Susceptibility and Resistance Monitoring for Novaluran 10% EC against Spodoptera frugiperda (J. E. Smith)

A Study was undertaken to assess the susceptibility of fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) to Novaluran (10% EC) by diet overlay bioassay method. Novaluran 10% EC was tested in vitro against S. frugiperda, obtained from four important Maize-producing tracts in Tamil Nadu. The susceptible population was obtained from FAW laboratory at TNAU which was in the 150th generation and further, reared up to 157th generation. The LC50 and LC95 values of Novaluran 10% EC to the susceptible population decreased from 0.865 to 0.746 ppm and 2.125 to 1.451 ppm, respectively. The susceptibility index of Novaluran was 1.159 and 1.464. The F157 population of S. frugiperda was used to conduct the preliminary discriminating dosage in Novaluran 10% EC and was 0.746 ppm.  Resistance monitoring studies of S. frugiperda from Coimbatore, Perambalur, Salem, and Theni districts revealed that the LC50 values of Novaluran 10% EC ranged from 0.792 and 0.930 ppm for Theni and Coimbatore, respectively. Novaluran 10% EC had the highest resistance ratio of 1.246 fold in the Coimbatore field population and the lowest resistance ratio of 1.061 fold in the Theni field population when compared with the TNAU FAW laboratory susceptible population of S. frugiperda