Safety and Acquisition Potential of <I>Metarhizium anisopliae</I> in Entomovectoring With Bumble Bees, <I>Bombus terrestris</I>

Abstract

In the context of integrated pest management with biological control and reduced pesticide use, dissemination of entomopathogenic fungi with insects has the potency to protect crops and specifically their flowers against pests and diseases. But before implementation of such entomovectoring system, a measurement of risks of the microbial biocontrol agent toward the vectoring insect is crucial. The essential contributions of this project are that 1) exposure of bumble bees, Bombus terrestris (L.) to powder containing 10(7) spores of the commercial biocontrol agent Metarhizium anisopliae strain F52 (Biol020) per gram, was safe; and 2) that when bumble bees had walked through this spore concentration (10(7) spores per gram) in a dispenser, their body carried 9.3 +/- 1 x 10(6) spores/bumble bee, and this was still 2.6 10(6) spores after a flight of 60 s, representing the average time to fly from the dispenser to the crop flowers. 3) In contrast, a 100-fold higher spore concentration (10(9) spores per gram powder) was highly toxic and the acquisition on the bumble bee body was only 2.5 times higher. Based on these data, future studies can start investigating the protection efficacy of this entomovector system with M. anisopliae and bumble bees without harming the vector and with a loading of the vector considered enough to obtain a good inoculation into and protection of the flowers.

Floral Odors and the Interaction between Pollinating Ceratopogonid Midges and Cacao

“…There is increasing global interest developing in precision pollination systems, including via optimizing commercially reared pollinators (Molet et al 2009), integrated pollination and pest management systems (Karise et al 2016;Smagghe et al 2013) and deployment of agricultural technologies in improvement of pollination (Olombria 2019). This may open up future opportunities to use an improved understanding of non-bee pollinators in commercial settings to improve crop production, especially in high-value crops with growing global demand such as cacao.…”

Distribution of a model biocontrol agent (Serenade® MAX) in apple and pear by mason bees and bumble bees

“…Furthermore, dry topical exposure to Bacillus subtilis had no deleterious impact on bumble bees (Mommaerts and Smagghe, unpublished data), and this has already been safely used in other pollinator‐vector experiments with honey bees and mason bees (Dedej et al ., 2004; Maccagnani et al ., 2009; Joshi et al ., 2020). However, this does not completely rule out that dry applications are safe for bees, as for instance exposure of Bombus terrestris to powder containing 10 7 spores of Metarhizium anisopliae strain F52 (Bio1020) per gram was harmless, while a 100‐fold higher spore concentration (10 9 spores per gram powder) was highly toxic (Smagghe et al ., 2013). Thus, future studies need to put more attention to evaluating the risk of microbial biocontrol agents towards the vectoring insect.…”

Biopesticides and insect pollinators: Detrimental effects, outdated guidelines, and future directions

“…In exposed nests of B. terrestris no acute toxicity was observed in workers nor reduced sexuals' production was recorded. However, high conidia concentrations (comparable to those used in the field) provoked a severe worker mortality, a reduced sexuals' production, and a total colony loss within few weeks (Smagghe et al, 2013) (Table S1).…”