Symbionts as Major Modulators of Insect Health: Lactic Acid Bacteria and Honeybees

Abstract

Lactic acid bacteria (LAB) are well recognized beneficial host-associated members of the microbiota of humans and animals. Yet LAB-associations of invertebrates have been poorly characterized and their functions remain obscure. Here we show that honeybees possess an abundant, diverse and ancient LAB microbiota in their honey crop with beneficial effects for bee health, defending them against microbial threats. Our studies of LAB in all extant honeybee species plus related apid bees reveal one of the largest collections of novel species from the genera Lactobacillus and Bifidobacterium ever discovered within a single insect and suggest a long (>80 mya) history of association. Bee associated microbiotas highlight Lactobacillus kunkeei as the dominant LAB member. Those showing potent antimicrobial properties are acquired by callow honey bee workers from nestmates and maintained within the crop in biofilms, though beekeeping management practices can negatively impact this microbiota. Prophylactic practices that enhance LAB, or supplementary feeding of LAB, may serve in integrated approaches to sustainable pollinator service provision. We anticipate this microbiota will become central to studies on honeybee health, including colony collapse disorder, and act as an exemplar case of insect-microbe symbiosis.

Isolation, Characterization and Identification of Probiotic Lactic Acid Bacteria (LAB) from Honey Bees

“…Isolation of LAB from the fourth instar larval gut in this study assumes significance as the larval gut is the target of highly pathogenic bacteria and fungi. Both royal jelly and worker jelly (bee bread + gland secretions + diluted honey) play an important role in the nature of bacterial composition as reported by Vojvodic et al, (2013) who found that first and second larval instars contained almost exclusively Acetobacteraceae, while later instars were dominated by one or two very different Lactobacillus spp. Acetobacteraceae includes acetic acid bacteria (AAB), a large group of obligate aerobic gram-negative bacteria, well adapted to sugary and alcoholised fluid such as vinegar, fruit juice, sap water, alcoholic beverages and flowers.…”

“…Lactobacillus is commonly associated with honey bees even in India (Pattabhiramaiah et al, 2012). Elsewhere L. kunkeei has been reported as the most common fructophilic species (Vasquez et al, 2012). Earlier different species of bacteria have been reported from the pollen (CorbyHarris et al, 2014) and honey stomach (Tajabadi et al, 2011).…”

“…The sugar-loving and flower-associated Gluconobacters are among the predominant bacterial groups in bees (Hamdi et al, 2011). While both AAB and LAB may play a role in nutrient processing in adult bees, they contribute to larval immunity during the early and fragile stage of honey bee development (Vojvodic et al, 2013). Royal jelly is considered highly antimicrobial, possessing a pH between 3.6 and 4.2, with many peptides active against gram-positive and gramnegative bacteria, fungi and yeasts.…”

“…Symbionts play a major role in maintaining the health of the host animal, including insects, especially honey bees. LAB is a key symbiotic micro-organism in bees, providing not only adequate nutrition but also host immunity against pathogens (Vasquez et al, 2012). At present, acaricides and antibiotics are extensively used in apiculture to manage the ectoparasitic Varroa mite syndrome.…”

“…Honey bees possess a diverse LAB microbiota in their honey crop, acquired by consuming pollen and nectar and through contact with older bees of the colony. All the extant honey bee species possess Lactobacillus and Bifidobacterium within the crop in biofilms (Vasquez et al, 2012), with potential to inhibit American Foul Brood-causing Paenibacillus larvae growth on agar plate (Forsgren et al, 2009). Especially, Lactobacullus kunkeei is predominantly found in A. laboriosa honey in Nepal (10 8 cfu per gram honey), followed by A. mellifera honey in Africa.…”