Prey consumption 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 a natural enemy against small arthropod pests including whiteflies, thrips, spi- der mites and aphid. This mirid is also successfully mass reared under factitious prey for commercial purposes. In the present study we assessed and com- pared the prey consumption, weight gain and conver- sion efficiency in females of two populations of M. pygmaeus, from mainland Portugal and the Azores, fed on single prey diets of Ephestia kuehniella Zel- ler (Lepidoptera: Pyralidae) eggs, or Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) eggs. We found that female’s prey consumption on eggs of T. abso- luta was higher than that of E. kuehniella, presum- ably due to the comparative size/amount of biomass of the eggs. Translating prey consumption in biomass ingested, we only found 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 mainland Portugal and Azorean populations fed on alternative prey. From an applied perspective, our results are a contribution to the decision-making on the use of the most effective biocontrol agents for different prey and/or agroecosystem contexts.