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There are more than bacteria, viruses and fungi around; are you looking at protists in your reared insects?

Published on: March 3, 2023

Hello there, I am Edouard Bessette, Early Stage Researcher n°4 from the Insect Doctors programme. Since my last research highlight from January last year, my PhD journey has brought to me to Copenhagen in June 2022.

When I have arrived in Copenhagen, I chose to study the interactions between reared house crickets (Acheta domesticus) and naturally occuring gregarine parasites. To date, there are no data regarding the potential effects that gregarines can have on this reared cricket species. Moreover, there is no molecular data for this species of gregarine and their phylogenetic relationship to other species remains unexplored so far. Thus, implementing methods to obtain uninfected control crickets and controlled infection, I am studying the effects of gregarines on different life traits of the cricket host. It has been shown in other studies on orthopterans that gregarines can reduce the weight, feed consumption and the fecundity of insect hosts. as well as increasing their development time (Harry 1970; Simmons 1990; Zuk 1987; Johny, Muralirangan, and Sanjayan 2000). Eventually, such effects in mass rearing systems could impact the quality of the insect production.

Other ‘protists’ of interest, or previously considered as protists, are the microsporidia. They are now considered as a basal group of fungi and can cause extensive damage to mass-reared invertebrates. Those parasites were my main focus when I started my PhD, but I did not succeed to implement them in my previous insect models, Galleria mellonella and Tenebrio molitor. However, we recently came across a report of reared cricket in the UK (Gryllus bimaculatus) that have been found to be infected since, at least, 2018 (Tokarev et al. 2018). So we also intend to better comprehend the life cycle of this microsporidium and the effects it could have on its host, Gryllus bimaculatus.

At the same time we are also assessing the presence and prevalence of those microsporidia and protist parasites (including gregarines and others) in different reared insect species through laboratory and omics data mining investigations. Through this, we aim to ascertain how those parasites are distributed.

With all these new insights and research avenues, the remaining months of my PhD will be intense and focused.

References

Harry, Owen G. 1970. ‘Gregarines: Their Effect on the Growth of the Desert Locust (Schistocerca Gregaria)’. Nature 225 (5236): 964–66. https://doi.org/10.1038/225964a0.

Johny, S., M. C. Muralirangan, and K. P. Sanjayan. 2000. ‘Parasitization Potential of Two Cephaline Gregarines, Leidyana Subramanii Pushkala and Muralirangan and Retractocephalus Dhawanii Sp. n. on the Tobacco Grasshopper, Atractomorpha Crenulata (Fab.)’. Journal of Orthoptera Research, no. 9: 67–70.

Simmons, L.W. 1990. ‘Post-Copulatory Guarding, Female Choice and the Levels of Gregarine Infections in the Field Cricket, Gryllus Bimaculatus’. Behavioral Ecology and Sociobiology 26 (6). https://doi.org/10.1007/BF00170897.

Tokarev, Yuri S., Katy M. Peat, Julia M. Malysh, and Igor V. Senderskiy. 2018. ‘Discovery of a Novel Microsporidium in Laboratory Colonies of Mediterranean Cricket Gryllus Bimaculatus (Orthoptera: Gryllidae): Microsporidium Grylli Sp. Nov.’ Parasitology Research 117 (9): 2823–29. https://doi.org/10.1007/s00436-018-5970-z.

Zuk, Marlene. 1987. ‘The Effects of Gregarine Parasites, Body Size, and Time of Day on Spermatophore Production and Sexual Selection in Field Crickets’. Behavioral Ecology and Sociobiology 21 (1): 65–72.