Competition between two biocontrol agents attacking the thrips, Gynaikothips ficorum (Marchal) (Thysanoptera: Phlaeothripidae), infesting the Cuban laurel, Ficus nitida Thunb., in Egypt

Abstract

The insect fauna is present in the curled Cuban laurel leaf (Ficus nitida Thunb.) infested with the Cuban laurel thrips, Gynaikothrips ficorum Marchal (Thysanoptera: Phlaeothripidae), in Giza, Egypt, which included pests, predators, and parasitoids. The present study dealt with the presence of two natural enemies of G. ficorum, i.e., the anthocorid predatory bug, Montandoniella moraguesi Puton (Hemiptera: Anthocoridae), and the eulophid parasitoid, Pediobius thysanopterus Marchal. (Hymenoptera: Eulophidae). Inspection of infested leaves revealed the presence of the thrips and the two natural enemies all year round. Numbers of the thrips showed 2 peaks (9500 and 12,000 individuals/100 infested leaves) in 2016 recorded in March and November, respectively. The associated predatory bug, M. moraguesi, occurred in two peaks in March and August by 8000 and 8500 individuals/100 infested leaves, respectively. Meanwhile, the eulophid parasitoid, P. thysanopterus, appeared in low population densities and by only one peak in October 2016 and in August 2017. The same trend for populations of the three concerned insect species was found in 2017. Generally, the very low population of the parasitoid resulted from a severe competition through the dominant voracious predator M. moraguesi that feeds not only on the thrips but also on the larvae and pupae of P. thysanopterus inside their host (G. ficorum) nymphs and prepupae.