Evaluation of infestation of chewing insect Pests of Cotton Crop and Their Management

Abstract

This research project was accomplished at four experimental sites of southern Punjab in order to underline the insect pest’s population dynamics of cotton and their predators. Eggs and adult Population counts of American bollworm (ABW), Pink bollworm (PBW) and spotted bollworm (SBW) are presented in the undergoing paragraphs. The three years study showed that adult count of ABW was at extreme in October 2014, 2016 and September 2015 at site-I. Similar population trends were observed in 2014 for ABW at site-II. During three years egg and adult count of ABW at site-III was in order: 2014> 2015> 2016. At site-IV population of adults started increasing, reached a maximum in August, and declined slightly in September and October 2014. During 2015, ABW adult count was maximum in September. Similar population trend of ABW was observed during 2016 at site-IV. The egg counts of ABW was maximum in September 2014 at site-I. During 2015, it was maximum in October, and July 2016. At site-II, maximum eggs count of ABW was found during October in 2014, 2015 and 2016, respectively. At site-III, maximum egg count of ABW was observed in July 2014, in August 2015 and in September 2016, respectively. Maximum egg counts of ABW at site-IV during 2014, 2015 and 2016 were observed in the months of August, October and September, respectively. Adult counts of PBW was highest in September during 2014, 2015 and 2016 in each year at site-I. At site-II, highest adult population of PBW was recorded in October 2014, 2015 and September 2016. At site-III, highest PBW population was observed in September 2014, October 2015 and September 2016. At site-IV highest mean egg counts of PBW was noted in October 2014, 2015 and 2016. Highest egg counts of PBW was noted in September each year at site-I. Mean number of eggs of PBW was found highest during September in 2014, 2015 and 2016 each year, at site-II. Highest average egg number of PBW was enumerated in September 2014, September 2015 and October in 2016, at site-III. The highest average count of eggs of PBW was noted during September 2014, October 2015 and August 2016, at site-IV. The highest adult population of SBW was recorded at site-I during October 2014, July 2015 and September 2016. At site-II, highest adult SBW was observed during September 2014 and 2015 each, and in October 2016, respectively. Highest average adult population of PBW was noted in September 2014, August 2015 and September 2016, respectively at site-III. At site-IV, the highest adult population of SBW was found in September 2014, August 2015 and October 2016. Eggs count of American bollworm was significantly affected by period (P<0.05) and variety (P<0.001). Egg count of PBW was significantly affected by varieties and egg count of spotted boll worm was affected by period (P<0.001) and variety (P<0.001) at site-I. Adult population size of American bollworms (ABW) at site-I was affected significantly by period (P<0.001) and variety (P<0.001). Pink bollworm (PBW) and Spotted bollworms adult counts were affected significantly (P<0.05) by period and variety. Average egg count of ABW, PBW and SBW showed significant differences for period and varieties. Host plant susceptibility index (HPSI) showed that cotton variety IUB-33 had highest HPSI in 2014 at site-I and site-II, and Lalazar and MNH-988 had highest HPSI at site-III and site-IV in 2014. Eggs count of ABW, PBW and SBW were non-significantly affected by humidity level (P>0.05), temperature (P>0.05) and wind speed (P>0.05) at all sites. Average number of adults ABW, PBW and SBW was also not affected by temperature, humidity level and wind speed and was non-significant (P>0.05) at all sites. Correlation coefficients between populations of lady beetle (predator) and ABW, PBW, SBW were low and non-significant during the year 2014. The correlations between spider (predator) and ABW, SBW populations were low and non-significant but low and significant for PBW population in this year. The correlations between both predator’s prey populations were high and significant (P<0.01) during 2014 at site-I. During 2015, correlation between lady beetle and ABW, SBW populations were positive low non-significant and negative low non-significant, respectively. PBW had lower but significant (P<0.05) correlations with lady beetle population. Spider population bore very low non-significant correlation with ABW, negative very low non-significant correlation with SBW and low but significant (P<0.05) correlation with PBW population. Mutual correlation between predator’s populations was very low and significant. In 2016, correlation analysis showed that population of lady beetles moderate and significant (P<0.001) with populations of ABW, PBW and SBW. Spider populations also showed intermediate to high and significant (P<0.001) correlations with ABW, PBW and SBW populations along with lady beetle population at site-I. At site-II, the correlations coefficients for lady beetle population and ABW, PBW and SBW were significant (P<0.001) and high in 2014. Spider population showed highly significant (P<0.001) but moderate to high correlations with ABW, PBW and SBW populations. During 2015, the second year of research, the correlations between prey (ABW, PBW and SBW) and lady beetle population were moderate but highly significant (P<0.01) at site-I. Spider population showed similar pattern of correlations during this year in the region but had highly significant and high correlation with lady beetle population. Lady beetle population had very low to low and non-significant correlations with ABW and SBW populations, respectively. A moderate and highly significant correlation coefficient was found between lady beetle and PBW populations. Population of spiders had similar type of correlations with ABW, SBW and PBW i.e. very low to low negative non-significant for former two and moderate but significant with the later. At siteIII, during 2014, correlations between lady beetle population and ABW were highly significant and high, PBW very high and highly significant, and SBW moderate and highly significant. Spider population had low to moderately high and significant correlations with ABW, PBW and SBW populations. In 2015, lady beetle population had very low to low negative non-significant correlations with ABW and SBW populations and low non- significant correlation with PBW population too. Spiders showed very low to low and non-significant correlations with population of ABW, PBW and SBW during this year in the region. Correlations between lady beetle and prey (ABW, SBW and PBW) were moderate to high and significant. Spider population had low to moderately high correlations with ABW, PBW and SBW populations in this region. During 2014, the correlations between lady beetle population and prey (ABW, PBW, SBW) populations were moderate to high and significant (P<0.001). Spider population had low, moderate and high but significant correlations with SBW, ABW and PBW populations during this year at site-IV. During 2015 at site-III, correlation coefficients between populations of lady beetle and chewing pests (ABW, PBW, SBW) were low to moderate and significant except for SBW that had nonsignificant correlation. Correlations between spider and chewing pest (ABW, PBW, SBW) populations were also in lower to intermediate range during this year yet they were significant (P<0.05). Lady beetle and chewing pest populations had negative and very low to low correlations that were also non-significant at site-IV.