Ecological studies on the wax scale insect Waxiella mimosae (Signoret) and the mealybug Trabutina serpentina (Green) infested Tamarix trees in Giza Governorate

Abstract

Ecological studies have been conducted on the population of the wax scale insect Waxiella mimosae (Signoret) and the mealybug Trabutina serpentina (Green) infesting Tamarix trees for 2 successive years (2016-2017) and (2017 and 2018) in Giza Governorate. Obtained results showed that both insects' population were higher in the 1 st year than the 2 nd one. W. mimosae recorded about 3-4 peaks of total population in 1 st and 2 nd year, respectively. The highest population of insects was recorded in September 2016, and the nymphal stage was the most numerous than other stages. The highest rate of increase was recorded in the 1 st year with 2.97 with temperature ranged between (15.13-24.00°C) and average relative humidity of 51.93%. It recorded 4 annual overlapping generations/year, the longest generations recorded 195 and 165 days from October till April in both years. Two parasitoids (with a new record parasitoid in Egypt) and two predators were recorded associated with W. mimosae in low densities that appeared mostly in spring months. The effect of mean temperature was significant on the insect population but the relative humidity effect was insignificant in both years. T. serpentina recorded 4 and 3 peaks in the 1 st and 2 nd year, respectively. The highest population was in 1 st December and 1 st February in the 1 st and 2 nd year, respectively. The highest rate of increase was recorded in 1 st year with 2.5 in mid-January 2017. Whereas, it recorded 3 annual overlapping generations the longest one was from mid-December till 1 st of May 2017 with 135 days in the 1 st year while in the 2 nd year each one of the 3 overlapping generations recorded 75 days. The effect of the three studied weather factors was insignificant. One associated parasitoid was recorded in low density.