Seasonal impact on life-fertility table parameters of Oligonychus sapienticolus Gupta infesting banana under Gangetic Basin of West Bengal, India

Aim: The aim of the present study was to investigate the impact of seasonal variation on life-fertility table of Oligonychus sapienticolus Gupta.Methodology: Adult mite population were collected from infested banana leaves and reared under laboratory condition. A cohort of 100 eggs laid at a time by a population of 100 gravid females was considered for the experiment. This cohort was used for constructing of age specific life-fertility table. Seasonal impact on different life-fertility table parameters were studied by using different formulas. Results: The perusal of data showed that the net reproductive rate, finite rate of increase and innate capacity for increase in number were highest during summer months, but mean generation time, doubling time and corrected generation time declined with increase in temperature. Interpretation: The study concludes that this mite prefer hot and dry climatic condition for better growth and development. So, during this period appropriate management measures against this mite will avoid the chances of yield loss of banana plantation

Aptitud biológica de poblaciones de Bemisia tabaci (Gennadius) Biotipo B (Hemiptera: Aleyrodidae) con diferente susceptibilidad al insecticida thiametoxam / Fitness of Bemisia tabaci (Gennadius) B Biotype (Hemiptera: Aleyrodidae) populations with different levels of susceptibility to the thiametoxam insecticide

In two field-collected populations of de Bemisia tabaci (Gennadius) B biotype previously selected with the neonicotinoid insecticide thiamethoxam (NEO-R, NEO-N), and a population susceptible to insecticides (SUSC), the level of response to the insecticide thiametoxam, as well as the life and fertility tables were determined. At LC95, the NEO-R population showed a resistance ratio (RR95) value of 8.8-fold, an intrinsic rate of increase (r m) of 0.72. The fitness of the NEO-R and NEO-N populations in relation to the SUSC was 1.5 and 2.0, respectively. The RR95 value for NEO-N was 1.9-fold; it's r m value was 0.082, while in the SUSC population was 0.041. The developmental time of egg and adult were longer in NEO-R population, while the nymph and pupa lasted longer in the NEO-N and SUSC populations. The developmental time was different in the three NEO-R, NEO-N, and SUSC populations with 19.7 d (315.84 degree days or dd), 15.7 d (250.4 dd) and 18.5 d (296.6 d), respectively. The populations previously selected with thiamethoxam did not reproduce faster than their susceptible counterpart.