Population Ecology of the Cotton Mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on Okra Plants in Luxor Region, Egypt

Among several pests infesting okra plants, the cotton mealybug, Phenacoccus solenopsis (Hemiptera: Pseudococcidae) is considered one of the most destructive pests. Field trials were conducted in a private field in Esna District, Luxor Governorate, Egypt, during two successive growing seasons (2021 and 2022) with the aim to study the seasonal fluctuation of P. solenopsis population infesting okra plants (Balady cultivar). Furthermore, the impacts of both climatic conditions and plant age on the seasonal variation of the tested insect pest were determined. The results indicated that P. solenopsis infested okra plants from the first week of March until the end of July, and had three peaks of activity per season, which were recorded in the first week of April, third week of May, and fourth week of June. The mean total population density of P. solenopsis per 10 leaves over the whole first season was 235.96±16.05 individuals and for the second season, it was 242.13±17.01 individuals. June was the most favourable month for P. solenopsis population increase (as measured during weekly inspections), while March was the least favorable in both growing seasons. Pooled effects of environmental conditions and plant ages had a strong relationship with P. solenopsis population density, with an Explained Variance (EV) of 93.26% in the first season and 95.09% in the second season, during the two seasons. Daily mean relative humidity was the most effective variable in explaining changes in the population density of P. solenopsis for the 1st season (2021), while the it was the major element influencing the changes in population in the 2nd season. On the other hand, the daily maximum temperature was clearly the least effective factor in population changes during both seasons. The data presented here can aid to monitor the oscillations in the population density of this pest.