Interactions among the Predatory Midge Aphidoletes aphidimyza (Diptera: Cecidomyiidae), the Fungal Pathogen Metarhizium brunneum (Ascomycota: Hypocreales), and Maize-Infesting Aphids in Greenhouse Mesocosms

Abstract

The generalist entomopathogenic fungus, Metarhizium brunneum, has proved to have great potential as a versatile biological pest control agent. The gall midge Aphidoletes aphidimyza is a specialist predator that occurs naturally in Europe and has been successfully used for aphid suppression. However, the interaction between these two biological control organisms and how it may affect the biological control of aphids awaits further investigation. As part of the EU-supported project INBIOSOIL, this study was conducted in greenhouse conditions to assess the possible effects of combining both biological control agents. In a randomized complete block design, sweet corn (Zea mays var. saccharata) plants were grown in large pots filled with natural soil or natural soil inoculated with M. brunneum. At the third leaf stage, before being individually caged, plants were infested with Rhopalosiphum padi and A. aphidimyza pupae were introduced in the soil. Aphidoletes aphidimyza midge emergence, number of living midges and number of aphids were recorded daily. The presence of conidia in the soil and on leaves was assessed during the experiment. At the conclusion of the experiment, the number of live aphids and their developmental stage, consumed aphids, and A. aphidimyza eggs was assessed under stereomicroscope. This study’s findings showed that the presence of M. brunneum did not affect A. aphidimyza midge emergence. However, longevity was significantly affected. As the study progressed, significantly fewer predatory midges were found in cages treated with M. brunneum compared to untreated cages. Furthermore, by the end of the study, the number of predatory midges found in the Metarhizium-treated cages was four times lower than in the untreated cages. Both daily and final count of aphids were significantly affected by treatment. Aphidoletes aphidimyza applied alone suppressed the aphid population more effectively than M. brunneum applied alone. Additionally, the aphid population was most suppressed when both agents were combined, though the suppression was less than additive.

Influence of the plant interacting entomopathogenic fungus Beauveria bassiana on parasitoid host choice-behavior, development, and plant defense pathways

“…Generally speaking, the consequences of microbe-plant-insect interactions are complicated and rely on many factors [ 18 ], especially when considering higher trophic levels (i.e., parasitoids and predators), and potential adverse effects between EF and natural enemies are important to consider [ 19 , 20 ]. Previous studies have shown compatibility between EF and beneficial arthropods [ 21 – 23 ], but there are also reports of EF causing higher mortality, lower fecundity and reduced longevity in predators and parasitoids, and other studies have shown competition for resources between the two groups of natural enemies [ 24 – 26 ]. We know that EF may influence the performance (e.g.…”

Weeds as Reservoirs of Beneficial Insects to Control Pests in Crops

“…Larvae of Allograpta oblicua (Say) (Syrphidae) fed on the aphid, although Gamboa et al (2016) found Chrysoperla carnea (Stephens) (Chrysopidae) the main predator of In this study, 25 adults and 14 larvae of Aphidoletes spp (Diptera: Cecidomyiidae) were preying on Aphis gossipii in Lepidium virginicum (Table 3). The larva of the fly can consume 50 aphids in 1 day (Campos de Azevedo et al 2017), which shows the potential of the insect to manage aphids in crops. Other Diptera found in smaller numbers were adult Chamaemyiidae (Diptera) (n = 3).…”

Non-target effects of Metarhizium brunneum (BIPESCO 5/F 52) in soil show that this fungus varies between being compatible with, or moderately harmful to, four predatory arthropods

“…Amongst those females that emerged, fecundity was not affected by treatment. Our previous greenhouse study showed that the number of A. aphidimyza midges emerging from M. brunneum-treated soil and the number of eggs laid were not affected by fungal presence; however, the number of midges was four times higher in the control than in the treatment at the end of the experiment (Azevedo et al, 2017).…”