Potentialities of Mermithid nematodes for the biocontrol of blackflies (Diptera: Simuliidae) - a review

Mermithids of three genera and species are known to parasitise North American Simuliids, and a more varied Mermithid fauna probably exists [cf. RAE/B 51, 135]. The host specificity of Mermithid parasites of Simuliids is variable, but the nematodes do not appear to infect other stream fauna. The sporadic distribution of Mermithid parasites of Simuliids among potential biotypes may be associated with a relatively inefficient mode of dispersal for such nematodes. Detailed information is lacking concerning the stages in the life-cycles of these pathogens and their synchronisation with those of the Simuliid host. Mermithids cause pathogenic effects on several Simuliid tissues, but no information is available concerning physiological manifestations of Mermithid parasitism in the flies. A brief review of the present state of knowledge of Simuliid taxonomy and bionomics is presented. The potentialities of Mermithid nematodes for the biological control of Simuliids are assessed and a feasible research programme presented in relation to the present state of knowledge of Mermithid-Simuliid interrelationships..