Imagine an STD that made you extra eager for sex. Oh, and it makes you sterile.
This STD exists—in insects.
Researchers working in a lab that studies field crickets came into work one day only to find, much to their dismay I imagine, that their colony had been infected with a virus. But, as they say in science, when life gives you lemons, thoroughly analyze them and publish the results.
Shelley Adamo and colleagues at Dalhousie University recently published an article in the Journal of Experimental Biology describing this accidental infection and how it made their crickets not only ignore being sick, but actually made them super randy.
The virus, Insect Iridescent Virus type 6 (or IIV-6 for short) has been known to infect insects for a long time. The virus infects the fat body, an extremely important organ in insects required for the function of their immune system, among other things. They’re “iridescent” viruses because they make the fat body of the insect glow blue.
Researchers in the Adamo lab got the first hint that there was something amiss when some females in their colony stopped laying eggs. They cut open a cricket and noticed its insides had turned blue. Using electron microscopy, they confirmed that the fat body was indeed full of tiny little hexagonal viruses. The DNA of those hexagons made the definitive diagnosis: IIV-6.
So what happened to the infected crickets?
First, the virus killed off their baby-makers. Females’ ovaries withered and they stopped producing eggs. Males still made sperm, but those sperm could no longer swim. Basically, it made them all sterile.
But that didn’t stop them from having sex.
There was no difference in mating behavior between infected and uninfected females. With or without eggs, they were happy to accept a courting male. Males on the other hand not only kept on courting, but they became even more enthusiastic about it. Uninfected males tended to wait an average of 600 seconds before starting to “sing” to a female—the equivalent of cricket flirting. Males infected with some other kind of pathogen, like bacteria, were not really in the mood. They waited about 800 seconds to sing. But the males infected with IIV-6, the ones without working sperm, only waited about 200 seconds. They were ready to go.
The researchers predicted that the virus could be transmitted sexually from cricket to cricket. Otherwise, why manipulate them into mating even when they’re sterile? As you’ve probably guessed, they were right. This sneaky virus had taken over the cricket’s immune system, tricking them into thinking they weren’t sick, and then got them all hot and bothered so that they could spread the virus far and wide.
IIV-6 isn’t the only sexually-transmitted insect virus. Another virus, called Hz-2v infects a type of moth (Helicovera). This virus also manipulates its host’s sexual behavior to increase its chances of spreading.
It’s a dangerous world out there for a fun-loving insect. Unfortunately, I don’t think that tiny bug-sized condoms are going to take off any time soon.
Related blog post:
Infected with love: a viral aphrodisiac in crickets (Jalees Rehman at SciLogs)
Adamo SA, Kovalko I, Easy RH, & Stoltz D (2014). A viral aphrodisiac in the cricket Gryllus texensis. The Journal of experimental biology PMID: 24625650
Burand JP, Tan W, Kim W, Nojima S, & Roelofs W (2005). Infection with the insect virus Hz-2v alters mating behavior and pheromone production in female Helicoverpa zea moths. Journal of insect science (Online), 5 PMID: 16299596