Ecology of Icerya purchasi Maskell, 1879 (Homoptera: Margarodidae) on clementine trees at Sidi Moussa (Central Mitidja, Algeria)

National Higher School of Agronomy 16200 El Harrach Algiers, Algeria Laboratory of Medicinal and Aromatic Plants, Department of Biotechnologies, Faculty S.N.V University of Blida 1 – Algeria Corresponding author email: m.biche@ensa.dz Received: 08.10.2020. Accepted: 20.11.2020 In order to establish the better communication between applied entomology and fundamental ecology to consider an integrated control against the Australian cochineal Icerya purchasi Maskell, 1879 (Homoptera: Margarodidae) the most formidable pest for citrus fruits, a study on the Spatio-temporal dynamics of the parasite were followed for two years in a clementine orchard in Western Mitidja in Algeria. Ten-day samples of leaves and twigs were carried out from 2017 to 2018. The level of I. purchasi infestation is very high throughout the study period when the minimum threshold exceeds 400 individuals, with three intense periods of infestations: spring, summer and fall during the two years. The population of young larval stages is the largest during the two years of study with 13,323 individuals (62.8 %) and 13,968 individuals (54.4 %) in 2017 and 2018 respectively against 7896 individuals (37.2 %) in 2017 and 11,715 individuals (33.5 %) in 2018 for adults. Tukey's pairwise comparison test on the companion plan shows that the 2018 one is the most important from an overall effective point of view (ANOVA, p <0.01, Tukey's test p<0. 01). The Cross-Correlation Test shows the presence of a time lag (p = 0.0371, p<0.05) and the maximum overall abundance was reported around mid-July for both campaigns. Statistical tests show that females show the same fertility during the two campaigns (ANOVA, p >0.05). peak fertility in 2017 was reported in mid-June, while peak fertility was reported in mid-July for the 2018 campaign. The Cross-Correlation Test shows a very significant time lag from one month to another (p = 0.0064, p <0.01)