Voracity and conversion efficiency in females of two feral populations of Macrolophus pygmaeus, a biocontrol agent of Tuta absoluta

Abstract

Macrolophus pygmaeus (Rambur, 1839) (Hemiptera: Miridae) is a polyphagous predator used in programs of biological control and integrated pest management as natural enemy against small arthropod pest populations, including whiteflies, thrips, spider mites and aphid. This mirid is also successfully mass reared under factitious prey for commercial purposes. In the present study we assessed and compared the voracity, weight gain and conversion efficiency in females of two populations of M. pygmaeus, one from Portugal mainland and the other from the Azores, fed on single prey diets of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, or Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) eggs. We found that female’s voracity on eggs of T. absoluta was higher than that of E. kuehniella, presumably due to the comparative size/amount of biomass of the eggs. Translating voracity in biomass ingested, we only find a significant difference for consumption on E. kuehniella eggs by M. pygmaeus from the Azores. Despite the smaller size of females from the Azores, they were able to consume more prey and ultimately reaching a similar body weight and conversion efficiency compared with females from mainland, independently of the prey provided. Our results are in line with a previous study, showing differences in the life-history traits of M. pygmaeus from Portugal mainland and Azorean populations fed on alternative preys. From an applied perspective, our results are a contribution to the decision-making on the use of the most effective biocontrol agents for different preys and/or agroecosystem contexts.