Ecological studies on two mealybug species (Hemiptera)‎ and their predator on navel orange trees at Qalubiya governorate, Egypt

الملخص EN

Citrus mealybug Planococcus citri (Risso) (Hemiptera: Pseudococcidae) and Egyptian fluted mealybug, Icerya aegyptiaca (Douglus) (Hemiptera: Monophlebidea) are serious insect pests, attack the navel orange trees and cause a severely considerable damage.

The present study aimed to determine mealybug generations under the studied conditions and the proper time for their control.

Field studies were carried out on P.

citri and I.

aegyptiaca on 100 navel orange leaves and 25 twigs in half monthly samples, at a private farm in Qalubiya Governorate, Egypt throughout two years 2018 and 2019.

The obtained results showed that P.

citri population had three peaks of infestation in the first year (2018) in June 1st, July 2nd and August 2nd.

In the second year (2019) two peaks were recorded on 1st week of July and 2nd week of September.

The Egyptian mealybug I.

aegyptiaca had one peak in both years occurred in the second week of September in first year and in second week of October the second year.

Two peaks of abundance during the first year 2018 recorded for the associated predator, Rodolia cardinalis (Mulsant) (Coleoptera: Coccinellidae), in June 2nd and in the October 1st.

During the second year of study, it had two peaks in June 1st and October 1st .

There was simultaneous occurrence of the total population of P.

citri and I.

aegyptiaca and its associated predator R.

cardinalis.

Positive correlation between Max., Min.

temperatures and the total population of P.

citri and I.

aegyptiaca was determined.

On the other side there were negative correlation of relative humidity and total population during the two years of study.-