Potential Role of the Eastern Mosquitofish (Gambusia holbrooki) in the Spread of the Harmful Fish Parasite, Asian Tapeworm Schyzocotyle (Bothriocephalus) acheilognathi

Biological control of undesirable organisms and pathogens often involves the introduction of alien species into new regions. However, alien species themselves pose a potential threat to local ecosystems and economies. The Eastern mosquitofish Gambusia holbrooki is recognised as a dangerous invasive species, but despite this, it is still used for biological control of mosquito larvae, a potential vector of malaria plasmodium transmission to humans, on the Black Sea coast of the Caucasus. We focused on the species composition of helminths in this fish species. We detected adult nematodes Pseudocapillaria (Pseudocapillaria) tomentosa and cestodes Schyzocotyle acheilognathi (formely Bothriocephalus acheilognathi). The above nematode was observed for the first time in fish of the genus Gambusia. Importantly, the cestode S. acheilognathi, which we found in G. holbrooki, is the most successful invasive alien parasite species in freshwaters of the planet and is extremely hazardous to natural ecosystems and aquaculture as it can cause mass mortality of young fish. Thus, the current practice of transferring mosquitofish between water bodies on the Black Sea coast of the Caucasus to control mosquito larvae may contribute to the undesirable spread of a harmful quarantine fish parasite.