Suppression of Escherichia coli O157:H7 by Dung Beetles (Coleoptera: Scarabaeidae) Using the Lowbush Blueberry Agroecosystem as a Model System

Abstract

Wildlife as a source of microbial contamination is a food safety concern. Deer feces (scat) have been determined as a point source for Escherichia coli O157:H7 contamination of fresh produce. The ecological role of the scooped scarab (Onthophagus hecate (Panzer)), a generalist dung beetle species common in Maine blueberry fields, was explored as a biological control agent and alternatively as a pathogen vector between deer scat and food.A large-scale field survey of wildlife scat indicated that pathogenic E. coli O157:H7 was present, albeit at a low prevalence (1.9% of samples, n = 318), in the Maine lowbush blueberry agroecosystem. A manipulative field experiment verified that, should contact occur between deer scat and blueberry plants and fruit during the summer, contamination with E. coli O157:H7 can occur and persist for more than 72 h. For both the positive control and an experimental scat inoculation treatment, the levels of the bacterial population decreased over time, but at different rates (treatment x time interaction: F (1.9,18.8) = 358.486, P < 0.0001). The positive control inoculation, which resulted in a higher initial E. coli level on fruit, decayed at a faster rate than inoculation of fruit via scat in the experimental treatment.We conducted 2 laboratory studies to elucidate aspects of dung beetle feeding ecology as it relates to suppression of E. coli O157:H7 from deer scat to lowbush blueberry fruit. In both experiments, dung beetles buried the same amount of scat whether or not the scat was inoculated with the pathogen (F (1,6) = 0.001; P = 0.999 and (F (2,17) = 4.10, P = 0.147). Beetles feeding on E. coli inoculated deer scat were not found to vector the pathogen to fruit. In two studies, beetles lowered the amount of pathogenic E. coli persisting in soils compared to soils without beetles (F (2,9) = 7.757; P = 0.05 and F (2,17) = 8.0621, P = 0.004).Our study suggests that the dung beetle species, Onthophagus hecate, has the potential to contribute to the suppression of E. coli O157:H7 in agricultural landscapes.

Organic farming promotes biotic resistance to foodborne human pathogens

“…Kudva, Blanch, & Hovde, ). In our study, suppression of E. coli was seen for two dung beetle species, congeners in the genus Onthophagus (Figure a), consistent with previous results for a closely related species (Jones et al., ). Suppression of pathogenic E. coli largely scaled with beetles’ rates of faeces removal (Figure a); because the exotic dung beetle O. nuchicornis is intermediate in its faeces consumption rate, so too is this species intermediate in its ability to remove pathogenic E. coli (Figure a).…”

“…However, some food‐safety regulations (Beretti & Stuart, ) conflate several biodiversity‐friendly practices often deployed by organic farmers with greater risk of produce contamination. For example, organic farms often house particularly robust populations of songbirds and other wildlife (Bengtsson et al., ) that could possibly act as a reservoir for human pathogens (Jones et al., ), though the degree to which wildlife actually elicit foodborne disease outbreaks remains unclear (Atwill, ). Likewise, animal manures on organic farms may harbour human pathogens (Newell et al., ).…”

“…Indeed, farms can harbour a diverse community of faeces‐feeding beetles and microbes that rapidly remove animal faeces once deposited, and also kill or otherwise antagonize any pathogens they contain. For example, dung beetles (Coleoptera: Scarabaeidae) can rapidly remove livestock faeces from grazeable grassland (Losey & Vaughan, ) and, in one case, have been suggested to suppress pathogens in the faeces that they consume (Jones, Tadepalli, Bridges, Wu, & Drummond, ). Likewise, soil microbes contribute to degrading faeces (Chu et al., ), commonly suppress plant pathogens through some combination of competition and chemical antagonism (Weller, Raaijmakers, Gardener, & Thomashow, ), and hinder persistence of human pathogens (Franz et al., ).…”

A trait‐based framework for predicting foodborne pathogen risk from wild birds

“…For example, Wild Turkeys ( Meleagris gallopavo ) were predicted to have overall low crop contact rates in our study, likely because their range does not extend into a large portion of the farms surveyed. However, they may constitute significant food safety risks where they do occur because they have been found to carry STEC and intrude into agriculture in other settings (Jones et al, 2015).…”

Occurrence of Antibiotic Resistant C. jejuni and E. coli in Wild Birds, Chickens, Environment and Humans from Orang Asli Villages in Sungai Siput, Perak, Malaysia

“…In the current research, the insect-eating birds (Oriental Magpie Robin, Little Spider Hunter and Whiterumped Shama) are regarded as one of the sources of E. coli in the villages. Flies and beetles have been shown to be carrying E. coli (Choi et al, 2011;Jones et al, 2015;Puri-Giri et al, 2017).…”