The Ladybird: Dark Secrets of an Endearing Insect
Cute, charming and adored in popular culture, the subject of children’s books, nursery rhymes and logos for a number of well-respected organisations; you’d be forgiven for thinking the ladybird (Coccinellinae) a model for all other insects to adhere to.
But delve a bit deeper in to this little beetle’s private life and they may seem a bad choice for such positive attributions.
A number of studies over the last few decades have found this family of insect to be scandalously promiscuous, disease-transmitting cannibals.
A study by the University of Liverpool looking in to disease transmission in populations of the European ladybird found that one venereal disease causing sterility in females indicated a positive correlation with food availability. This resulted from increased attempts at breeding due to the favourable surrounding conditions, but meant that the very environment which would typically be conducive to an increase in population may actually result in the opposite.
Further research by Cambridge University found that ectoparasitic mites (the insect equivalent of pubic lice), leapt from individual to individual during copulation. These parasites may be linked to a condition in female ladybirds which lead them to produce male eggs with a bacterial infection. If this wasn’t bad enough news for the guys their delayed emergence due to the infection gave their newly-hatched sisters time to devour them as a post-natal meal.
If you need more evidence of their dastardly deeds, Dr Greg Hurst of University College London described the genus as ‘remarkably promiscuous’ after emerging from hibernation. He found that sexually transmitted diseases in ladybirds residing in London were far more rampant than their countryside counterparts. This is thought to be due to the abundance of prey species (greenfly specifically) that thrive in polluted environments and hence the subsequent increased sexual activity of ladybirds eager to reproduce in a food-rich habitat. Here it is estimated that between 80 and 95% of urban ladybirds have some form of STD; giving them the highest prevalence of venereal infections of nearly any insect.
Fortunately, the diseases ladybirds suffer in the UK are a lot milder than those found on the continent although it has been suggested that the invasive harlequin ladybird (Harmonia axyridis), originally an Asian species, has brought with it a new fungal infection via the USA. In fact, it is thought that already around 15% of the UK’s species already suffer from the disease. And with an increase in resource competition from their bigger, Asian-American counterparts our natives might have a tough time in the coming years.
With all this in mind the next time I see a ladybird crawling up my window frame I will no longer think of them as innocent little cuties, but as the incognito, unchaste little harlots of the insect world.
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