Formulation of weather-based criteria rules for the prediction of sucking pests in cotton (Gossypium hirsutum) in Punjab (original) (raw)
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Indian Journal of Agricultural Sciences
A study was conducted during 2005 and 2006 to develop a weather-based forecasting model for sucking pest in Bt-cotton (Gossypium hirsutum). The population dynamics of Jassid, Whitefly and Thrip with respect to meteorological parameters on Btcotton (cv. Ankur 651 during rainy season 2005 and cv RCH 34 during rainy season 2006) under 3 dates of sowing was conducted during crop seasons at research farm of the Punjab Agricultural University, Ludhiana. The results revealed that a decrease in maximum temperature (6-7 o C from normal of >38 o C) and minimum temperature (4-5 o C from normal of >27 o C) and sunshine hours (5-7 hr from normal of >8 hr) favour the population build up of cotton jassid (Amrasca bigutulla Shir). Whereas an increase in temperature (maximum temperature >32 o C; minimum temperature >25 o C) and sunshine hours (>9 hr) coupled with decreased relative humidity favoured the build up of cotton whitefly (Bemisia tabaci Genn.). Of these parameters, the contribution of increase in the number of sunshine hours has been significant with respect to its build up. Cotton thrip (Thrips tabaci Lindi.) appeared on cotton during its early vegetative stage and ceased its activity with the onset of southwest monsoon. Peak population of thrips was recorded as soon as the maximum and minimum temperature crossed 39 and 25 o C and morning and evening relative humidity was below 55 and 35%, respectively along with more than 9 hr of sunshine. On the contrary a decrease in temperature and sunshine hours and increase in RH coupled with a heavy rainfall led to cessation of thrips activity in cotton.
Influence of Weather Parameters on Population Dynamics of Thrips and Whitefly on Bt Cotton
The thrips and whitefly population was commenced from SMW 30 and SMW 32 and peak population was observed in SMW 32 and SMW 36 respectively. Thereafter the population decreased up to SMW 52. The correlation among peak population of thrips and weather factors showed that maximum temperature, morning relative humidity and rainfall positively affected the thrips population, whereas negative correlation obtained with minimum temperature and evening relative humidity. Whitefly population showed positive correlation with maximum temperature and rainfall, whereas negative correlation with minimum temperature and humidity.
Cotton is an important fibrous crop and called as white gold of Pakistan. Like many other crops, various chewing and sucking insect pests attack on different Bt and non-Bt cotton genotypes. Furthermore, metrological factors (especially temperature, relative humidity and rainfall) also play vital role in the population dynamics of sucking insect pest complex like jassid, aphid, thrips and mites. The present study was conducted on six cotton cultivars (3 Bt and 3 non-Bt) to monitor the population dynamics of thrips in relation to abiotic climatic factors. Interaction effect was found significant in Bt varieties but not for non-Bt cultivars. Average thrips population per leaf on various Bt and non-Bt varieties showed that the CIM-557 along with BT-703 had the highest number of thrips density while Bt variety FH-113 had the lowest thrips population per leaf. Similarly, in relation to thermal effect, high thrips population was recorded at 29-35 o C but population declined at 40°Ċ. Findings are helpful for appropriate management of sucking complex in case of cotton crop.
2020
Nowadays approximately 20 thrips species have been reported to infest cotton internationally causing considerable yield losses. Monitoring thrips is hard as they are about minute and are mysterious feeders, which build thrips not easy to manage by chemical. The present investigations were designed to test out the seasonal outbreak of thrips individuals on two cotton varieties and effect of ecological components markedly temperature, humidity and rainfall on it. The impact of different sowing dates was also intentional. The results indicated that thrips population was maximum (11.83/leaf) found on Cyto-179 and (8.22/leaf) on IUB-2013. In the first sown cotton, the peak activity of thrips was during the second week of August while for second planting time it was first week of August. The results from correlation analysis showed the positive association was found between the thrips abundance and temperature. While the analysis showed unconstructive correlation of relative humidity and rainfall with thrips abundance. Both cotton cultivars proved extra vulnerable to the thrips hit. A biotic factors played momentous role in the growth along with surveillance of this pest. So, by managing the agronomic factors, e.g. sowing time, cotton yield could be enhanced by reducing the infestation of thrips.
Nowadays approximately 20 thrips species have been reported to infest cotton internationally causing considerable yield losses. Monitoring thrips is hard as they are about minute and are mysterious feeders, which build thrips not easy to manage by chemical. The present investigations were designed to test out the seasonal outbreak of thrips individuals on two cotton varieties and effect of ecological components markedly temperature, humidity and rainfall on it. The impact of different sowing dates was also intentional. The results indicated that thrips population was maximum (11.83/leaf) found on Cyto-179 and (8.22/leaf) on IUB-2013. In the first sown cotton, the peak activity of thrips was during the second week of August while for second planting time it was first week of August. The results from correlation analysis showed the positive association was found between the thrips abundance and temperature. While the analysis showed unconstructive correlation of relative humidity and rainfall with thrips abundance. Both cotton cultivars proved extra vulnerable to the thrips hit. A biotic factors played momentous role in the growth along with surveillance of this pest. So, by managing the agronomic factors, e.g. sowing time, cotton yield could be enhanced by reducing the infestation of thrips.
Acta Phytopathologica et Entomologica Hungarica, 2013
Among sucking insect pests, the incidence of a leafhopper [Amrasca biguttula biguttula (Ishida)] and a whitefly [Bemisia tabaci (Gennadius)] remained active through the cropping season in varying population density. Thrips [Thrips tabaci (Lindemann)] population was only observed in early stages of the crop growth. The leafhopper population attained its peak during 2 nd half of July and was maximum (9.2 nymphs/3 leaves) in the year 2008. The population of whitefly adults was maximum (14.8 adults/3 leaves) in 2007 and it acquired its peak during end of July and again in end of September to early October. The incidence of thrips was maximum in June. The population of the A. biguttula showed significant positive correlation with minimum temperature (r=0.636; p=0.003), mean temperature (r=0.475; p=0.034), evening relative humidity (r=0.618; p=0.004) and rainfall (r=0.556; p=0.011). The correlation of B. tabaci population with minimum temperature was significantly positive (r=0.454; p=0.044). The multiple regression analysis revealed that all the weather parameters collectively accounted for variability in the A. biguttula and B. tabaci population with R 2 values ranging from 0.67-0.80 and 0.50-0.69, respectively, during different years.
2019
A study on population dynamics of thrips, Scirtothrips dorsalis Hood on Bt cotton was conducted at Anand Agricultural University, Anand during Kharif 2017-18. The incidence of the pest started from last week of July to end of crop season with peak activity in 2 nd week of December. The higher activity of this pest was noticed during November and December (8.24 to 14.24 thrips/leaf). The correlation coefficient data indicated that rainfall (r=-0.54**), wind speed (r=-0.61**), minimum temperature (r=-0.92**), morning relative humidity (r=-0.67**), evening relative humidity (r=-0.84**), morning vapour pressure (r=-0.92**) and evening vapour pressure (r=-0.82**) were highly significant negatively correlated with thrips population. The bright sunshine hour(r=0.57**) and evening vapour pressure deficit (r=0.65**) had highly significant positive correlated with the activity of thrips.
The first incidence of cotton thrips noted during mid July and peak activity during first fortnight of October when crop was in boll development stage. The population remains fluctuated and active throughout crop season. Maximum temperature exhibited significant positive correlation (r= 0.434) during first year and non significant positive correlation (r= 0.200) during second year while rainfall expressed significant negative correlation (r= -0.485) during first year and non significant negative correlation (r= -0.318) during second year.