Biotic stress is a major cause for pre and postharvest losses in agriculture. Food crops of the world are damaged by more than of 10,000 species of insects 30,000 species of weeds, 1,00, 000 types of diseases (due to fungi, viruses, bacteria and various microbes) and a 1,000 species of nematodes. Modern day management practices for the above specified stress factors largely depends on the utilization of synthetic pesticides. Pesticide misuse in numerous sectors of agriculture frequently has often linked to health issues and environmental pollution around the world. Thus, there is a growing interest in replacing or possibly supplementing the prevailing control strategies with new and safer techniques. One of the promising management tools in this new state of affairs for crop protection is microbial pesticides. At present, only 3% of plant protectants used globally are covered by bio pesticides, but their growth rate indicates an increasing trend in the past two decades. The discovery of insecticidal property of Bacillus thuringiensis (Bt) indicated a more extensive part of organism based natural control. Microbial pesticides comprise of a microorganisms (bacterium, fungus, virus or protozoan) or toxins produced by them as the active ingredient. The most commonly used microbial pesticides are entomopathogenic fungi (Metarhizium, Beauveria and Verticillium), entomopathogenic bacteria (Bt), entomopathogenic nematode (Steinernema and Heterorhabditis) and baculoviruses (NPV and GV) which able to cause disease in insects. Microbial insecticides are promising alternative to ecologically disruptive pest control measures as they are no longer harmful to the environment and non target organisms. If deployed appropriately, microbial insecticides have capability to bring sustainability to global agriculture for food and food safety.
An experiment was conducted to study and document the copulation duration and effect of mating on female calling behaviour of Indian population of an invasive pest, Spodoptera frugiperda (J. E. Smith). Results showed that 58.39% of the females in absence of males and 88.18% of females in presence of males exhibited calling on first scotophase and onset time of calling was early in females in presence of males. Calling length and calling bouts varied significantly with increase in age in virgin females, while in multiple mated females it showed declining trend. The copulation duration of S. frugiperda varied between 78.00±7.35 min to 197.14±11.06 min with maximum copulation duration and percentage of females mated was observed on second scotophase. The fecundity of multiple mated females ranged between 841 to 1849 with mean of 1176±113 while in single mated females it ranged between 476 to 1368 with mean of 878±175. Practically our results indicated that the calling and mating takes place on first scotophase and it was on peak in second scotophase. This information can be used in formulating biorational molecules, which may modulate calling behaviour and improve mating disruption in S. frugiperda for its management.
The effect of elevated CO2 (570±25ppm) on the brown plant hopper (BPH) population, rice yield parameters, and efficacy of buprofezin (0.05%) in terms of spray volume was studied in an open top chamber (OTCs) during rainy season 2017 and 2018. The pest population was observed to be higher during 2017 compared to the rainy season of 2018. Under elevated CO2, rice plants had more vegetative tillers (18%) and reproductive tillers (22.1%), but there was a decrease in 1000-seed weight (11.2%), seed number per panicle (3.91%), and grain yield (18.8%) in comparison to ambient CO2 grown rice plants. The spray volumes of 700, 600, 500, and 400 l/ha each caused higher BPH mortality under ambient CO2 compared to elevated CO2. A spray volume of 500 l/ha did not prove as effective under elevated CO2 as under ambient CO2. Lower efficacy of spray volume of 500 l/ha under elevated CO2 could be ascribed to higher canopy size under elevated CO2 due to higher tillering. Increased crop canopy size under elevated CO2 may thus require higher spray volume to ensure proper coverage. Results of the study suggested a need to revise spray volume recommendations to facilitate effective management of BPH under climate change.
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