D3020: Provision borne microbes and the development of Megachile rotundata

The alfalfa leaf cutting bee, Megachile rotundata F. is an important field crop pollinator. The females provision its offspring with pollen from different plant species. Pollen has a diverse community of microbes that are symbiotically associated with bees and contribute to their health and survival. Additionally, Lactobacillus clade is the most abundant microbe in the gut helping bees to digest pollen and has demonstrated resistance to a broad range of antibiotics. Despite the apparent importance of the microbial community, evidence concerning the direct and indirect affects of provision microbes on physiology, growth rate, and survival is lacking in M. rotundata . To test this hypothesis, we reared larva on the following provision treatments: pollen provision with antibiotics, sterile pollen provision, sterile pollen provision + Lactobacillus micheneri , natural pollen provision + Lactobacillus micheneri , and natural pollen provision (control). Gamma irradiation was used to sterilize the natural pollen provision. We hypothesis that individuals reared on manipulated diet showed significant effects on the growth rate, survival, and mass of larvae, prepupae, and cocoon. Larvae reared on sterile pollen appeared to weigh normal, showing that pollen microbiome does not contribute towards attaining optimal mass. However, antibiotics negatively affected larval, prepupal and cocoon weight. This study on solitary bee larvae presents an interesting contrast to the fact that microbes are thought to strongly affect their hosts' fitness. Finally, showing that the dependency for growth and development on microbes is not a universal phenomenon across solitary bees.