Neonicotinoid-induced pathogen susceptibility is mitigated by Lactobacillus plantarum immune stimulation in a Drosophila melanogaster model

Abstract

Pesticides are used extensively in food production to maximize crop yields. However, neonicotinoid insecticides exert unintentional toxicity to honey bees (Apis mellifera) that may partially be associated with massive population declines referred to as colony collapse disorder. We hypothesized that imidacloprid (common neonicotinoid; IMI) exposure would make Drosophila melanogaster (an insect model for the honey bee) more susceptible to bacterial pathogens, heat stress, and intestinal dysbiosis. Our results suggested that the immune deficiency (Imd) pathway is necessary for D. melanogaster survival in response to IMI toxicity. IMI exposure induced alterations in the host-microbiota as noted by increased indigenous Acetobacter and Lactobacillus spp. Furthermore, sub-lethal exposure to IMI resulted in decreased D. melanogaster survival when simultaneously exposed to bacterial infection and heat stress (37 °C). This coincided with exacerbated increases in TotA and Dpt (Imd downstream pro-survival and antimicrobial genes, respectively) expression compared to controls. Supplementation of IMI-exposed D. melanogaster with Lactobacillus plantarum ATCC 14917 mitigated survival deficits following Serratia marcescens (bacterial pathogen) septic infection. These findings support the insidious toxicity of neonicotinoid pesticides and potential for probiotic lactobacilli to reduce IMI-induced susceptibility to infection.

Novel probiotic approach to counter Paenibacillus larvae infection in honey bees

“…[18]. Findings from model systems support this approach, showing that Lactobacillus plantarum Lp39 can improve the innate immune response and resistance towards opportunistic infection in Drosophila melanogaster [19]. A reduction of pesticide toxicity via Lactobacillus rhamnosus GR-1 supplementation in D. melanogaster [20] and protection against harmful microorganisms by various Lactobacillus and Bifidobacterium spp.…”

“…Preliminary experiments identified honey bee alpha-tubulin (XM_391936) to be most stably expressed (compared to ribosomal protein S5 [XM_624081], microsomal glutathione-S-transferase [XM_394313], and UDP-glucuronyltransferase [XM_392727]) endogenous control under our specific set of experimental conditions, and thus was chosen as the internal standard for normalization as per MIQE guidelines [40]. cDNA was diluted tenfold and used for qPCR reactions with the Power SYBR Green kit (Applied Biosystems) as previously described [19]. All qPCR reactions were performed in DNase-and RNase-free 384-well microplates using a Quant Studio 5 Real-Time PCR System (Applied Biosystems) and analyzed with associated software.…”

The direct and indirect effects of environmental toxicants on the health of bumble bees and their microbiomes

“…The effects of xenobiotic chemicals on the microbiomes of animals is emerging as an integral part of the ecotoxicology of harmful compounds (41). Cadmium (42,43), selenium (44), copper (45), imidacloprid (46), and hydrogen peroxide (as measured as ROS (47)) have been shown to alter host microbiomes in non-bee study systems. Outside of our work, little is known about how these toxicants affect bee microbiota, with field-realistic selenium and cadmium exposure altering proportions of microbes in honey bees (22), and imidacloprid not affecting the microbiome of honey bees (48).…”

The Canmore Declaration: Statement of Principles for Planetary Health

“…Inspiring examples included the work of indigenous physician Dr Nicole Redvers in conjunction with the Artic Indigenous Wellness Foundation; recipient of the $1 million Artic Inspiration Prize, Dr Redvers and her team work toward revitalizing community health with language, culture, traditional foods and practices [75]. There were numerous other examples of ecological solutions with multi-dimensional benefits, including restoring beneficial microbes to improve soil health and crop yields, detoxifying environmental pollutants, and even buffering against colony collapse disorder in bees by protecting against pesticide immunotoxicity [76]. When applied to low-income communities, such as those in sub-Saharan Africa, ecological strategies to food production are showing community benefits not only for health but also for employment, training and women's empowerment [77].…”