Having had the yellow fly in this post identified for me as the Yellow Dung Fly, Scathophaga stercoraria, I looked up this insect in more detail, only to discover that this insect has been one of several subjects, investigated in the laboratory with respect to the matter of sexually transmitted diseases in insects. And yes, there's a scientific paper for me to share with you all! Namely:
Sexually Transmitted Diseases Of Insects: Distribution, Evolution, Ecology And Host Behaviour by Robert J. Knell & K. Mary Webberley, Biological Reviews of the Cambridge Philosophical Society, 79(3):, 557-581 (August 2004) [Full paper downloadable from here]
WARNING: FOR SOME REASON, THAT LINK TRIGGERS A MALWARE ALERT FROM MY ANTI-VIRUS SUITE. DOWNLOAD THE FILE AT YOUR OWN RISK. MY ANTI-VIRUS SUITE LISTS THE FILE AS CLEAN AFTER A SCAN. DOUBLE CHECK IF YOU CHOOSE TO DOWNLOAD THIS FILE.
Further on in the paper, we find the following interesting snippet - the hilariously gruesome part being highlighted below:Knell & Webberley, 2004 wrote:ABSTRACT
Sexually transmitted diseases (STDs) of insects are known from the mites, nematodes, fungi, protists and viruses. In total 73 species of parasite and pathogen from approximately 182 species of host have been reported. Whereas nearly all vertebrate STDs are viruses or bacteria, the majority of insect STDs are multicellular ectoparasites, protistans or fungi. Insect STDs display a range of transmission modes, with ‘pure’ sexual transmission only described from ectoparasites, all of which are mites, fungi or nematodes, whereas the microparasitic endoparasites tend to show vertical as well as sexual transmission. The distribution of STDs within taxa of insect hosts appears to be related to the life histories of the hosts. In particular, STDs will not be able to persist if host adult generations do not overlap unless they are also transmitted by some alternative route. This explains the observation that the Coleoptera seem to suffer from more STDs than other insect orders, since they tend to diapause as adults and are therefore more likely to have overlapping generations of adults in temperate regions. STDs of insects are often highly pathogenic, and are frequently responsible for sterilizing their hosts, a feature which is also found in mammalian STDs. This, combined with high prevalences indicates that STDs can be important in the evolution and ecology of their hosts. Although attempts to demonstrate mate choice for uninfected partners have so far failed it is likely that STDs have other effects on host mating behaviour, and there is evidence from a few systems that they might manipulate their hosts to cause them to mate more frequently. STDs may also play a part in sexual conflict, with males in some systems possibly gaining a selective advantage from transmitting certain STDs to females.
STDs may well be important factors in host population dynamics, and some have the potential to be useful
biological control agents, but empirical studies on these subjects are lacking.
Now that is seriously creepy - a sexually transmitted disease that makes its dead victims look like ripe females, in order to attract males to become infected. I'm sure there's an Alien type science fiction novel awaiting penning based upon this.Knell & Webberley, 2004 wrote:(4) Fungi
The majority of fungi that have been reported as being STDs come from the order Laboulbeniales. These fungi are all ectoparasites of arthropods, and usually exhibit a high degree of specificity in the parts of the insect that they will grow on (Weir & Beakes, 1995). This high degree of specificity has led to a number of them being identified as being transmitted during mating because they are found on the parts of the male and female insects that come into contact with each other during mating. That this corresponds with transmission during mating has been confirmed experimentally several times, originally by Peyritsch (1875, cited in Whisler, 1968; arguably the first description of an STD of an insect), and several times since (Whisler, 1968; Strandberg & Tucker, 1974). Both of these latter studies also found that the fungus can also be transmitted by other contact between conspecifics. It is often thought that the Laboulbeniales do little harm to their hosts (Weir & Beakes, 1995), but Strandberg & Tucker (1974) found a significant increase in mortality in earwigs (Labidura riparia) infected with Filariomyces forficulae.
A second group of sexually transmitted fungus is the Massospora species. Their periodical cicada hosts continue to fly and mate even when heavily infected and abdominal segments have broken away to expose the mass of infectious conidia left in their place (Soper, Delyzer & Smith, 1976; White & Lloyd, 1983). A final and rather unusual example of an STD fungus is that of Entomophthora muscae infecting Musca domestica. Møller (1993) described how this fungus causes swelling of the abdomen of freshly killed cadavers of its host, making them resemble gravid females. Male flies attempt to mate with these cadavers and in doing so become infected.
