Morphometry and Preffered Feeding Site of Egyptian Mealybug (Icerya Aegyptiaca Douglas) on Croton Codiaeum Variegatum Plant

Abstract

Morphometrical analysis of the mealybug, Icerya aegyptiaca (Douglas) was studied on Codiaeum variegatum under laboratory conditions between August and December, 2010. Microscopic slides were prepared for the existing life forms according to the conventional entomological method. Observations were made on the body structure, appendages and dimensions as possible future tools in taxonomic key’s construction. Result showed that there were three instars and adult stage. There was a significant variation in the body structure, length and dimensions of body appendages of the various larval forms of the insect. The mean body length (cm) of the various instars was significantly different and was as follows: first instars having 1.62±0.03, second instars 1.86±0.03 third instars 2.97±0.07 and the adults to be 3.97±0.03 respectively. Body width dimension was not significantly different and first instars: 0.83±0.02; second instars: 1.04±0.01; third instars: 1.79±0.06 and the adults: 1.85±0.01 respectively. Mean antennal length was recorded to be: 1st instars: 0.53±0.02; 2nd instars: 0.64±0.01; 3rd instar: 0.84±0.02 and the adults: 0.89±0.01 respectively. The progressive development in the length of the stylet with respect to the age of the insects was thought to be affected by feeding requirement and environmental conditions and there was a progressive increase in the dimensions of nearly all the parameters examined after each moult.

Keywords: Body appendages, Codiaeum variegatum, Icerya aegyptiaca, instars, instars, morphometry.