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

L Boukhobza,M Biche,R Belguendouz

doi:10.15421/2020_247

Abstract

In order to establish better communication between applied entomology and fundamental ecology to consider an integrated control against the Australian cochineal Icerya purshasi 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 3 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 (62.79%) and 13,968 individuals (54.39%) in 2017 and 2018 respectively against 7896 individuals (37.21%) in 2017 and 11,715 individuals (33.50%) 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≤1%, Tukey's test p≤1%). The Cross-Correlation Test shows the presence of a time lag (p=0.0371, p≤5%) 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≤5%). 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≤1%).

Highlights

Scale insects or coccidae are the most formidable enemies of citrus fruit, both in terms of the qualitative and quantitative depreciation they cause to the fruit as well as its tree
The level of I. purchasi infestation was very high over the studied period, with the minimum threshold exceeding 400 individuals during the two years
Observations on the population dynamics of I. purchasi on clementine orchards were obtained during two years

Summary

Introduction

Scale insects or coccidae are the most formidable enemies of citrus fruit, both in terms of the qualitative and quantitative depreciation they cause to the fruit as well as its tree. Among the Margarodidae, the most worrying species for citrus orchards is I. purchasi, commonly known as the Australian mealybug. It originates from Australia but has spread to all parts of the world (DeBach, 1964). It is considered a major pest of citrus (Carvalho et al, 1996). Damage by this scale insect is both direct (sap extraction, wounds on the bark, deformations and seeps) as well as indirect, through a high production of honeydew which allows the development of sooty mold. The sanitary quality, due to diseases and pests that make them unfit for consumption, preservation and export, depriving Algeria of foreign exchange earnings (Belguendouz, 2014)

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