Assessment of Earias vittella (Fabricius) Egg Distribution in Cotton Crop at Multan, Pakistan: A Comprehensive Guideline for Developing a Pest Scouting Method
Assessment of Earias vittella (Fabricius) Egg Distribution in Cotton Crop at Multan, Pakistan: A Comprehensive Guideline for Developing a Pest Scouting Method
Muhammad Tahir Jan1, Sarfraz Ali Shad2, Mushtaq Ahmad Saleem3 and Muhammad Binyameen2,*
ABSTRACT
The knowledge of oviposition preference by female insects is a basic requirement for developing insect pest scouting methods to determine the potential damage and to apply control measures for key pest like Earias vittella in cotton. Field experiments were conducted to assess the distribution of E. vittella eggs within the cotton plant. Out of 240 plants inspected, E. vittella females laid 204 and 194 eggs on 40.9% and 36.9%of the plants in 2011 and 2012, respectively. Spearman Rank Correlation showed that a significant and positive relationship (association) existed between the number of infested plants or plant parts and number of eggs laid. In every week, an average of 6.1±1.2 plants were infested with13.6±2.7 eggs in 2011 and 5.5±1.1 plants with 12.9±2.2 eggs in 2012. Four and three peak egg-laying periods were observed in 2011 and 2012, respectively. Taylor’s power law of regression showed an aggregate spatial pattern distribution of eggs for E. vittella in plants in both years. Variance-to-mean ratio, the chi-square test index, and Lloyd index of patchiness indicated uniform eggs distribution for both years. Within the plants, the most preferred oviposition sites were just below the terminal portion on such structures as the leaves, terminal buds and NE leaves. The current study regarding the site selection for oviposition provides information that can be used to develop guidelines for E. vittella management in cotton production.
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