Australasian Science: Australia's authority on science since 1938

Locust Mating a Risky Business

By Stephen Luntz

A wasp targeted copulating locust during the most recent plague.

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During the peak of the 2010–11 swarm, Australian locust faced a 10% chance of dying a particularly horrible death if they chose to have sex. Black digger wasps reproduce by paralysing grasshoppers and crickets, dragging them to a burrow and laying eggs inside the body. When the eggs hatch they feed on the still-living Orthoptera.

Dr Darrell Kemp of Macquarie University’s Evolutionary and Behavioural Ecology Research Group says that little is known about the lifecycle of this particular species, but related wasps feed only on nectar after they emerge or “don’t feed at all”. Most, if not all, nutrition comes from the unfortunate individual in which the wasp was laid.

Kemp observed plague locusts around the time of their first mating and found that females had a one-in-200 chance of being stung by a wasp while on their own. The risk for males was even lower, as the wasps would usually let a single male go, possibly because the smaller males lack the nutrients needed to sustain the young wasps to adulthood.

However, during a single mating event lasting 10–20 minutes, the risk of the wasp stinging the female was one-in-ten. “Male locust were never directly paralysed by wasps – either while solo or in couple – but males in captured pairs lost their lives solely because they could not detach from their paralysed female partner and were ultimately buried alive...

The full text of this article can be purchased from Informit.