Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 2009
Publication Date: July 1, 2010
Citation: Suh, C.P., Westbrook, J.K. 2010. Relationship between population estimates of cotton fleahoppers (Hemiptera: Miridae) obtained by terminal and whole plant examinations. Journal of Entomological Science. 45:1-7. Interpretive Summary: The standard technique for assessing cotton fleahopper abundance in cotton involves direct counts of adults and nymphs on plants. However, many producers avoid or neglect sampling for cotton fleahoppers because this procedure is laborious and time consuming. We examined the distribution of cotton fleahopper adults and nymphs within cotton plants to determine whether reliable population estimates of fleahoppers could be obtained by sampling only the upper (terminal) portion of plants. Our findings indicate that the terminal portion accounts for the majority of fleahoppers on plants. Our results also demonstrate that reliable population estimates can be obtained by sampling only the terminal portion of plants, regardless of the time of day when plants are sampled. Because sampling the terminal portion of plants takes considerably less time and effort than sampling entire plants, it is anticipated that producers and consultants will readily accept and use this sampling practice. By sampling fields for cotton fleahoppers on a regular basis, the incidence of unnecessary or untimely insecticide application for this insect pest will be greatly minimized.
Technical Abstract: The standard sampling technique used to quantify cotton fleahopper, Pseudatomoscelis seriatus (Reuter), abundance in cotton, Gossypium hirsutum L., involves direct counts of adults and nymphs on plants. This method, however, becomes increasingly laborious and time consuming as plants increase in size. We examined the distribution of cotton fleahopper adults and nymphs within cotton plants to determine whether reliable population estimates could be obtained by sampling only the terminal portion of plants. Fleahopper distribution patterns were examined twice a day (0800-1130 h and 1300-1630 h) during the initial three or four weeks of pre-floral bud production in 2007 and 2008. Overall, the mean numbers and distribution patterns of fleahoppers observed during the morning and afternoon sampling periods were statistically similar. Consequently, time-of-day sampling effects were not observed. During both periods, significantly more adults and nymphs were observed in the terminal of plants than below the terminal. When the numbers of cotton fleahoppers (adults and nymphs combined) found on plants were regressed on the numbers of fleahoppers observed in the terminal of those plants, the r-squared and coefficient of variation values were 0.89 and 28, respectively. Based on the inverse of the regression slope, the terminal accounted for 74 percent of the fleahoppers observed on plants. Our results suggest reliable population estimates of fleahoppers can be obtained by sampling only the terminal portion of plants. However, this sampling practice may not provide the level of precision typically required in population research.