Crop protection chemicals known as pesticides are playing a significant role to ensure food security. Besides controlling pests in agriculture, they are also used in human and animal health programmes. Development of resistant pests poses a real challenge towards the effectiveness of these toxic pesticides leading to their increased application associated with residual toxicity in food and environment. An estimated 954 pest species which include arthropods, weeds and plant pathogens have developed resistance against various types of pesticides, viz. insecticides, herbicides and fungicides. Resistance development in pest populations is influenced by biological, genetic and operational factors. Various mechanisms involved in resistance development in insects, microbes and weeds are discussed. The extent of insecticide, fungicide and herbicide resistance in various pest species is also highlighted. Effective pest and resistance management practices require understanding the factors influencing its development. The important role of Insecticide Resistance Action Committee (IRAC), Fungicide Resistance Action Committee (FRAC) and Herbicide Resistance Action Committee (HRAC) for resistance management is indicated. Strategies to mitigate the resistance development in conventional pesticides, use of Plant Incorporated Protectants (PIPs) and biopesticides as alternative to chemical pesticides along with some general recommendations are suggested for adoption.
Phosphine fumigant is widely used to control stored insect pest infestation in grains. The study on Aluminium Phosphide (ALP) fumigation was conducted to find out the effect of relative humidity on concentration of phosphine. Aluminium phosphide (tablet) 56% formulation was used for fumigation of two stacks of pigeon pea grains, each of 4 MT capacities. During fumigation first stack the humidity was ranged 60 to 70% and another stack the humidity was between 50 to 60%. Fumigation procedure carried out as per National Standards of Phytosanitary Measures (NSPM) with dose rate of 3 tablets / MT for 10 days exposure period. Phosphine concentration was monitored in both stacks from 1 to 10 days after fumigation. After 24 hrs (1 day) of treatment the average phosphine concentration was 340 ppm in stack with higher humidity and terminal concentration (after 10 days) was 315 ppm, whereas in stacks with lower humidity the concentration was 309 ppm and 184 ppm after 24 hrs and 10 days respectively. The results revealed that concentration of phosphine was directly proportional to the humidity.
Regular movements of planting materials between countries pave the way for the entry of exotic pests. Despite rigorous quarantine regulations, various insect pests have hitherto entered India and raised biosecurity concerns. The occurrence of rugose spiraling whitefly, Aleurodicus rugioperculatus Martin and bondar’s nesting whitefly, Paraleyrodes bondari Peracchi on coconut crop has drawn the attention of the scientific and farming community due to their unique damaging behavior and rapid progression. Understanding their invasion, a study was undertaken to explore their incidence pattern in West Bengal (India). The survey revealed the occurrence of these species in different regions and habitats. The species was confirmed by standard morphological characters and molecular techniques by amplifying the cytochrome oxidase gene (COI) of mDNA. The representative sequence of A. rugioperculatus and P. bondari has been deposited to the NCBI with accession numbers OP024192 and OP024193, respectively. At present, two species co-exist on coconut leaflets with a rare exception of Gause’s principle. The incidence and severity of these pests were found greater on coconut palms. The damage inflicted by siphoning of plant sap by A. rugioperculatus was more severe than P. bondari. A shift in the weather pattern and continuous dry spells favor their proliferation and spread. The extensive field survey identified potential natural enemies of these whiteflies in the Eastern region of the country. Coconut plays a significant role in the agrarian economy and this comprehensive work would be much useful as a diagnostic guide for farmers, researchers, extension workers and organizations.
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