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Exposure of honeybee (Apis mellifera L.) to pesticides disturbed normal physiological and behavioral functions required for normal foraging and colony maintenance. The present study was aimed towards establishing the mean lethal concentration (LC50) of three pesticides viz. carbamate (carbaryl), organophosphate (chlorpyrifos) and neonicotinoid (imidacloprid) in honeybees through feeding bioassay laboratory trial. Deleteriousness was confirmed through mortality rate, number of survival bees, acetylcholinesterase (AChE), total protein (TP) levels, AChE gene transcription level, and gut tissues histological analysis of exposed honeybees. Mean mortality rate was calculated for 96 h interval at three different concentrations of tested pesticides (5, 2.5, and 1.25 mg L−1), and LC50 values calculated for 48 and 96 h interval. AChE enzyme and TP level are determined by ELIZA and spectrophotometer, respectively. Results revealed that imidacloprid had the lowest LC50 (0.477 ng/bee) values as compared with carbaryl and chlorpyrifos. High mortality rate was observed at highest dose, being impidacloprid have more lethal effects as compared with other pesticides. Similarly, biochemical analysis revealed that imidiacloprid and chlorpyrifos significantly (P ≤ 0.05) increased AChE and TP levels, whereas carbaryl significantly (P ≤ 0.05) decreased them. Similarly, probe based RT qPCR revealed that imidacloprid and chlorpyrifos treatments significantly (P ≤ 0.05) enhanced the AChE level whereas carbaryl decreased it. Histological analysis showed that the gut tissues of honeybees exposed to pesticide treatment had substantial morphological abnormalities. In a nutshell, imidacloprid, carbaryl and chlorpyrifos have substantial toxic effects on all the study attributes of honeybees with imidacloprid being most toxic. [ABSTRACT FROM AUTHOR]

The present study was devised with an aim to assess pesticide risk toward honeybees (Apis mellifera L.) by detecting pesticide residues in pollen and nectar samples collected from various agricultural areas of Pakistan through high performance liquid chromatography analysis. Pollen and nectar were collected from 2016 to 2017 from different agricultural areas of Pakistan during a field survey. Pollen was collected by installing traps and nectar was collected through capillary method allied with centrifugation. The HPLC technique was used for fast and simple detection of pesticide residues of commonly used pesticides (imidacloprid, deltamethrin, chlorpyrifos, fipronil, thiamethoxam, carbaryl, profenophos and bifenthrin). Among a total of 100 pollen samples, 47% were found to be positive. The most frequently found residues were imidacloprid (11%), thiamethoxam (7%) and carbaryl (6%). Among all 100 nectar samples, 36% samples were positive and most abundant pesticides in nectar were imidacloprid (8%), thiamethoxam (6%) and fipronil (5%). In pollen samples, the residual level of imidacloprid and thiamethoxam was detected at a level of 0.032 - 0.76 ng/g and 0.055 - 0.78 ng/g, respectively while in nectar samples imidacloprid and thiamethoxam were detected at a level of 0.009 - 0.53 ng/g and 0.045 -0.76 ng/g, respectively. The results obtained suggest careful monitoring of pesticide used in order to save honeybee population. [ABSTRACT FROM AUTHOR]

The article discusses a study that determined the efficacy of two nematode species, Steinernema carpocapsae (Sc) and Heterorhabditis bacteriophora (Hb) against the workers and nymphs of the subterranean termite Reticulitermes flavipes. Findings show that termite mortality in biossay is affected by different concentrations, nematode species, and degree of interaction between the nematodes and insecticides. The synergism between imidacloprid and nematodes, which caused more than 50 percent mortality in most treatments, is explored.