Biology and Reproductive Parameters of Scymnus subvillosus (Coleoptera: Coccinellidae) on Saissetia oleae Crawlers

Abstract

The biology and reproductive performance of Scymnus subvillosus were investigated under laboratory conditions to evaluate its potential as a biological control agent against Saissetia oleae crawlers in perennial orchard systems. Developmental duration, survival rate, adult longevity, fecundity, and reproductive parameters were assessed using a diet of first-instar crawlers under controlled temperature and humidity conditions. The predator successfully completed its life cycle on S. oleae, indicating strong adaptability to scale insect prey. Larval development proceeded through successive instars with relatively high survival rates, particularly under moderate environmental conditions. Feeding activity was continuous throughout larval stages, with increasing prey consumption observed in later instars. Adult females exhibited significantly higher longevity and fecundity compared with males, with peak oviposition occurring during the early reproductive period followed by a gradual decline with age. Pre-oviposition and oviposition periods were influenced by prey availability, with optimal reproduction observed under abundant crawler supply. Life history parameters indicated favorable reproductive potential, including high net reproductive rate and moderate intrinsic rate of increase, supporting population persistence under field conditions. The predator demonstrated effective prey utilization, particularly targeting early instar crawlers, which are the most vulnerable stage of S. oleae. These biological traits suggest a strong functional role in regulating scale insect populations in orchard ecosystems.