First list of parasitoids in flies of medical, veterinary, and forensic importance in Rio Grande do Sul – Brazil

Necrophagous flies are of great importance for human and animal health. In places where their development occurs, parasitoids can be used as a tool to control these dipterans. In Brazil, the fauna of these parasitoids has been investigated in some regions. However, in Rio Grande do Sul, it is known the occurrence of only one species. Thus, this study aimed to create the first list of parasitoids in flies of medical and veterinary importance in Southern Brazil. Collections took place in the municipality of Pelotas (31º 42’ S; 52º 18’ W). Three replicates consisting of a 500 g bovine liver chunk placed in a tray were exposed to open air for 20 days. Then pupae were individualized and observed until their emergence. We identified 4,882 adult flies of Calliphoridae, Fanniidae, Muscidae, and Sarcophagidae. 4,040 parasitoids emerged, belonging to eight species, of which Nasonia vitripennis, Spalangia cameroni, Spalangia chontalensis, and Tachinephagus zealandicus are new records in Rio Grande do Sul state. Also, three undescribed species of the genus Aphaereta were collected. In spite of being the first attempt to inventory the fauna of hymenopteran parasitoids, this study may help in the development of management programs of these dipterans in the region.

Bacterial supergroup specific “Cost” of Wolbachia infections in Nasonia vitripennis

The maternally-inherited endosymbiont, Wolbachia, is known to alter the reproductive biology of its arthropod hosts for its own benefit. It is also known to induce both positive and negative fitness effects in many hosts. Here we describe the effect of maintenance of two distinct Wolbachia infections, one each from supergroups A and B, on the parasitoid host Nasonia vitripennis. We compare the effect of Wolbachia infections on various traits between uninfected, single A, single B, and double infected strains. Contrary to the previous reports, our results suggest that there is a “significant cost” associated with the maintenance of Wolbachia infections where traits like progeny family size, fecundity, longevity and rates of male copulation is compromised in Wolbachia infected strains. The double infection of Wolbachia has more detrimental impacts on the host as compared to single infections, while the supergroup B infections elicits the most pronounced negative effect. These findings raise important questions on the mechanism of survival and maintenance of these reproductive parasites in arthropod hosts.

Parasitic wasps do not lack lipogenesis

Fatty acids are crucial primary metabolites for virtually all creatures on earth. Most organisms thus do not rely exclusively on a nutritional supply containing fatty acids, but have the ability to synthesize fatty acids and triacylglycerides de novo from carbohydrates in a process called lipogenesis. The ubiquity of lipogenesis has been questioned by a series of studies reporting that many parasitic wasps (parasitoids) do not accumulate lipid mass despite having unlimited access to sugar. This has been interpreted as an evolutionary metabolic trait loss in parasitoids. Here, we demonstrate de novo biosynthesis of fatty acids from 13 C-labelled α- d -glucose in 13 species of parasitoids from seven families. We furthermore show in the model organism Nasonia vitripennis that lipogenesis occurs even when lipid reserves are still intact, but relative 13 C-incorporation rates increase in females with widely depleted fat reserves. We therefore conclude that the presumed ‘lack of lipogenesis' in parasitoids needs to be re-evaluated.