Microbial symbiosis and the control of vector-borne pathogens in tsetse flies, human lice, and triatomine bugs

Abstract

Symbiosis is a widespread biological phenomenon, and is particularly common in arthropods. Bloodsucking insects are among the organisms that rely on beneficial bacterial symbionts to complement their unbalanced diet. This review is focused on describing symbiosis, and possible strategies for the symbiont-based control of insects and insect-borne diseases, in three bloodsucking insects of medical importance: the flies of the genus Glossina, the lice of the genus Pediculus, and triatomine bugs of the subfamily Triatominae. Glossina flies are vector of Trypanosoma brucei, the causative agent of sleeping sickness and other pathologies. They are also associated with two distinct bacterial symbionts, the primary symbiont Wigglesworthia spp., and the secondary, culturable symbiont Sodalis glossinidius. The primary symbiont of human lice, Riesia pediculicola, has been shown to be fundamental for the host, due to its capacity to synthesize B-group vitamins. An antisymbiotic approach, with antibiotic treatment targeted on the lice symbionts, could represent an alternative strategy to control these ectoparasites. In the case of triatominae bugs, the genetic modification of their symbiotic Rhodococcus bacteria, for production of antiTrypanosoma molecules, is an example of paratransgenesis, i.e. the use of symbiotic microorganism engineered in order to reduce the vector competence of the insect host.

Grandeur Alliances: Symbiont Metabolic Integration and Obligate Arthropod Hematophagy

“…This arrangement may reflect an evolution-driven mechanism that reduces the risk of gene loss during symbiont genome degeneration while ensuring adequate levels of gene expression [119]. Interestingly, the genome of R. pediculicola lacks antibiotic resistance genes, suggesting that targeting this symbiont through antibiotic administration may be a novel method of controlling P. h. humanus infestations [120, 122]. …”

Evolution of hematophagous habit in Triatominae (Heteroptera: Reduviidae)

“…Blood as feed, although rich in proteins, does not have all the nutritional elements the triatomines need to survive, and therefore, these insects as bloodsuckers needed to develop a symbiotic relationship with microorganisms that produced vitamin B (thiamine, pantothenic acid, pyridoxine, folic acid, and biotin), which is insufficient in vertebrate blood (Douglas and Beard 1996;Sassera et al 2013). These symbionts are so important that most bloodsuckers store them in bacteriocytes or mycetocytes (Douglas 1989), cells that coat the ventricle of the mesenteron in the tsetse fly or in specialized organs known as mycetomes, present, for example, in lice (Anoplura) (Burkhart and Burkhart 2006).…”

Efficiency of an air curtain as an anti‐insect barrier: the honey bee as a model insect

“…Information on the wind speed from which insects stop their flight is lacking for most species, but it can be assumed that their flight activity is also sensitive to the wind. Understanding the wind sensitivity of strong flyers that are involved in the dissemination of human and animal vector‐borne and food‐borne diseases, such as house, tsetse, horse, deer, horn, stable and face flies, thus appears as very important . The sensitivity of insects to wind as a preventive approach to insect infestation has long been a subject of interest, as exemplified by the early study on flies investigating the anti‐insect effect of mechanical fans in eating areas…”

“…Understanding the wind sensitivity of strong flyers that are involved in the dissemination of human and animal vector-borne and food-borne diseases, such as house, tsetse, horse, deer, horn, stable and face flies, thus appears as very important. [24][25][26][27][28][29] The sensitivity of insects to wind as a preventive approach to insect infestation has long been a subject of interest, as exemplified by the early study on flies investigating the anti-insect effect of mechanical fans in eating areas. 30 To combat insect-borne diseases, air curtains might represent a promising approach to limit the spread of flying insects.…”