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- Prey consumption and conversion efficiency in females of two feral populations of Macrolophus pygmaeus, a biocontrol agent of Tuta absolutaPublication . Borges, Isabel; Oliveira, Luísa; Barbosa, Francisco; Figueiredo, Elisabete; Franco, José Carlos; Durão, Ana; Soares, António O.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, 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 prey consumption, weight gain and conversion efficiency in females of two populations of M. pygmaeus, from mainland Portugal and 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 prey consumption 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 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.
- Feeding preference and intraguild interactions between the parasitoid Trichogramma achaeae and the predator Macrolophus pygmaeus, two biological agents of Tuta absolutaPublication . Borges, Isabel; Oliveira, Luisa; Durão, Ana; Arruda, Patricia; Soares, António O.ABSTARCT: Tuta absoluta is an exotic species and a major pest of tomato crops in Europe. Macrolophus pygmaeus and Trichogramma achaeae are two biocontrol agents widely used in integrated pest management programs of the South American tomato pinworm Tuta absoluta. In this study, we evaluated under laboratory conditions the (i) voracity of M. pygmaeus females fed on single diets of Tuta absoluta eggs parasitized or unparasitized by Trichogramma achaeae, (ii) voracity and feeding preference of M. pygmaeus females provided with mixed diets of Tuta absoluta eggs unparasitized and parasitized by Trichogramma achaeae and (iii) effect of competitive and intraguild interactions between M. pygmaeus and Trichogramma achaeae on the number of Tuta absoluta eggs consumed and/or parasitized. Lastly, we assessed under field conditions the effect of interspecific and intraspecific interactions between natural enemies on the number of Tuta absoluta eggs consumed and/or parasitized.
- Ephestia kuehniella Zeller eggs as a surrogate host to test feeding preference and intraguild interactions between Macrolophus pygmaeus (Rambur) and Trichogramma achaeae Nagaraja and NagarkattiPublication . Costa Miranda Soares, António Onofre; Durão, Ana; Oliveira, Luisa; Arruda, Patricia; Borges, IsabelABSTRACT: Mass rearing of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) eggs is a laborious task requiring investment of time, equipment and man hour work. The use of a surrogate prey/host, as Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), easily obtained and maintain, could be an option to undertake experiments. The aim of this study was to test to what extent the eggs of E. kuehniella is a suitable surrogate host of T. absoluta eggs to test for feeding preference and intraguild interactions between Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) and Trichogramma achaeae Nagaraja and Nagarkatti (Hymenoptera: Trichogrammatidae). Our results shows that E. kuehniella eggs is a suitable surrogate host to test for feeding preference and intraguild interactions between natural enemies, taking in consideration that i) under single diet, feeding on T. absoluta eggs is expected to be twice that on E. kuehniella, ii) whether offering T. absoluta or E. kuehniella under different ratios of parasitized vs unparasitized eggs, feeding preference was always toward non-parasitized eggs iii) in conspecific experiments with increasing density of M. pygmaeus females, the results show an overall decrease on feeding of 38.7% of E. kuehniella compared with T. absoluta eggs but experiments with T. achaeae show an overall increase in parasitism rate of 78.2% of eggs toward E. kuehniella eggs iv) in heterospecific experiments with increasing density of both natural enemies, when using E. kuehniella eggs we found an overall decrease on feeding consumption of 30% and an increase of parasitism rate of 65%.