Seasonal occurrence of the broad mite, Polyphagotarsonemus latus (banks), on roselle and its control using botanical extracts

Abstract

The broad mite (Polyphagotarsonemus latus (Banks); Acari: Tarsonemidae) is a significant pest affecting a variety of host plants, particularly the yellow and dark red cultivars of Hibiscus sabdariffa (roselle), causing considerable economic losses. The present study, conducted from September 15, 2022, to April 12, 2023, at the Department of Plant Protection, University of Baghdad, evaluated the impact of the pest and assessed the efficacy of both alcoholic and aqueous extracts from Nerium oleander, Eucalyptus spp., and Mentha spp. in managing the mite. Laboratory assays showed that all tested extracts, at concentrations of 10, 20, and 30 mg/ml, effectively suppressed various developmental stages of the mite, with oleander extract causing the highest mortality rates, followed by eucalyptus and mint extracts. Notably, larvae experienced the greatest mortality after seven days, while eggs were the least susceptible. Field observations revealed the continuous presence of the mite population on roselle cultivars over six months, with higher infestation levels recorded on the yellow cultivar compared to the dark red. Population density analysis indicated greater numbers of eggs, larvae, nymphs, and adults on the yellow cultivar, with two distinct seasonal peaks, one in late November (autumn) and another in early April (spring). Among the botanical treatments, alcoholic oleander extract was the most effective, followed by eucalyptus and mint extracts, whereas the aqueous mint extract showed comparatively lower control efficacy. Based on the findings, the use of alcoholic N. oleander extract is recommended as the most effective botanical treatment for managing broad mite infestations in roselle.