Wheat is our main staple food crop and growing on largest area in the country. Globally 60% of the food requirement a common man gets from wheat crop. 20% calorie and 40% of food demand of world meet from wheat crop. According to the economics survey of Pakistan 2015 wheat containing the largest area under cultivation 9180 thousand hectares in Pakistan. The yield of wheat is 25.478 million tonnes during 2015. It shares 2.0 percent in the GDP and 10.0 percent in the agriculture . Many insect pest attack on the wheat from sowing up to harvesting and then in stores also. Army worm attack on the wheat when this was on harvesting stage and aphid on vegetative and earning stage. In which the most prominent species of aphid are Rhopalosiphum padi S. Schizaphis graminum R., Rhopalosiphum madis F. and Sitobion avenae F. Among these the most destructive aphid is Schizaphis graminum and have a wide range of host at least 60 species in which barley, sorghum , corn and wheat included. Army worm eat the leaves and some lower soft grains of the spike. The aphid damage the wheat by three ways. First one is that it directly suck the cell sap from the leaves and stems and from the spikes and cause the loss of yield of wheat crop. During sucking honey dew excrete on the plants that favors the growth of sooty mold that hinders the process of photosynthesis in the plants and cause the loss of spikes. Third on is that this also the source of spreading the diseases like yellow dwarf viruses, loose smut of wheat, yellow leaf rust of wheat etc. But the depart of agriculture of Punjab does not recommended any insecticides on the wheat.
In Pakistan nature provides a good control of these pests on the wheat as natural gift to us. The climatic conditions of our country does not provide the suitable environment to cause heavy loss in Pakistan now a days. But the trend of population of aphid slightly changed every year. At the early stage the aphid population is low because the at this the quality of food and also quantity affect the life cycle of the pest at the earing stage the aphid population increased gradually and reached its peak position due to the above mentioned reason. The favorable temperature of the development of the aphid is 7.7 to 25.2 degree centigrade and the optimum temperature is 25.2 degree centigrade. So at the earing stage peak population is also due to the optimum temperature. During optimum temperature the females of the aphid also giving birth to young-ones this process is known as parthenogenesis.
After that the population decreases and finished aphid at the harvesting stage. Insecticides are not recommended first reason is explained above the unfavorable climatic condition of Pakistan for aphid to cause heavy loss. Wheat is direct consuming crop so also avoid the insecticides because their residual affect of these chemicals directly affect on the health of the humans. Health is the prime objective but in Pakistan some pesticides industries gave the solution of aphid when this was at its peak stage insecticide. Because these industries try to sell their products in any way and reached their target of sale. This is very wrong practice giving to the farmers by pesticide dealers.
When the population at its peak then simple solution is that spray the cold water on the wheat the kill the aphid and population remained below the ETL level. During this season i also personally observed some cases that some farmers apply insecticides and no grain formation takes place after that. This also the negligence of the dealers of pesticide not seeing the field situation of the crop. Their main focus is only to achieve the sale target of the company. The grain formation does not takes place because insecticide apply when the crop is at pollination stage so this affect this process and crop fail to pollinate and grain does not produce. This insecticides also kill the many beneficial insects of the wheat crop just like lady bird beetles, chrysopa , black wasps and syrphid fly. Nature also provide natural enemies of aphid so that due to this reason also the population of aphid does not reached at the ETL level. Due to these reasons the insecticide are not recommended on the wheat crop.
Written by . Haseeb Jut