Chemical and biological approaches for citrus leafminer Phyllocnistis citrella stainton control in a Clementine Orchard, in Moulouya region of Morocco

Abstract

The citrus leafminer (CLM), Phyllocnistis citrella is considered an important pest in young citrus nurseries and plantations around the world, as Morocco. Since management of CLM is based primarily on the use of insecticides, a study was developed to use biological approaches along with rational and limited insecticide usage for an integrated management program based on degree-days (DD) required for insect generations. This study was conducted over three years (2017, 2018 and 2019) in Clementine (Citrus reticutala ‘Berkane’) fields located at Berkane area, Morocco. Citrus leafminer adults were monitored with two delta traps baited with pheromone capsules and checked weekly from early April to early September each year. Additionally, a weekly sampling of young leaves from new young shoots showing CLM injury symptoms was conducted to identify the status of larvae or pupae, and the influence of natural enemies (parasitoids and predators). During 2017 and 2018, four peaks of adult flights were observed while five peaks were detected in 2019. However, several overlapping generations occurred according to DD recorded during the study period (seven generations in 2017, six in 2018 and eight until early September 2019). The use of DD indicated that two insecticide applications in each 2018 and 2019 for control of CLM were not needed. The maximum infestation level detected was 90% in early August 2017, and 100% near the beginning and end of July for 2018 and 2019, respectively, with CLM larvae and pupae most detected. The maximum rate of parasitism was observed in non-treated controls in late July 2017 at 37%, early July 2018 at 48%, and late August 2019 at 32%. The parasitoids of CLM identified were Citrostichus phyllocnistoides, Semielacher petiolatus, Cirrospilus pictus (most abundant), Cirrospilus vittatus, Pnigalio sp. and Chrysocharis sp., while the main predators were ants, ladybugs and spiders.

Keywords:

• degree-days
• insecticides
• integrated management program
• parasitoids
• predators

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was supported by the National Institute for Agricultural Research of Morocco (Regional Center of Agricultural Research of Oujda). We thank the Triffa and Zniber Domains (heads and technicians) for their technical support, availability and valuable advice.