Quick estimation of egg number in compact ovisacs of pink hibiscus mealybug, Maconellicoccus hirsutus (Green)

Abstract

Estimating the number of eggs in a mealybug ovisac (= egg sac) is not only tedious but time consuming. Here, we explain a simple method to estimate the number of eggs in a mealybug ovisac using the ovisac parameters viz., length, width, weight. When subjected to correlation analysis these parameters revealed significant association (P = 0.01) between number of eggs per ovisac with ovisac length (r=0.81) and weight (r=0.69) but not with ovisac width. Further detailed step-wise regression analyses revealed that ovisac length (cm) and ovisac weight (mg) together can predict variability in the number of eggs to the tune of 72% (-110.45 + 897.61 x, + 28.72 x2; F =46.63; edf =36; P <0.0001). Further, ovisac length alone could predict the egg number to the tune of 66% (F = 70.42; edf = 36; P<0.0001). This method can speed up the mealybug egg estimation vis a vis population in both field as well as laboratory conditions.