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 1st year than the 2nd one. W. mimosae recorded about 3-4 peaks of total population in 1st and 2nd 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 1st 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 1st and 2nd year, respectively. The highest population was in 1st December and 1st February in the 1st and 2nd year, respectively. The highest rate of increase was recorded in 1st year with 2.5 in mid-January 2017. Whereas, it recorded 3 annual overlapping generations the longest one was from mid-December till 1st of May 2017 with 135 days in the 1st year while in the 2nd year each one of the 3 overlapping generations recorded 75 days. The effects of the three studied weather factors were insignificant. One associated parasitoid was recorded in low density.