MAYBE IT'S BETTER FOR SOME INSECTS TO STAY QUIET

Certain insects have sound producing structures or organs that are generally used to attract mates. While this action has shown to be effective in gaining access to the opposite sex, certain antagonists such as parasitoids have found it beneficial in detecting potential hosts. Over long periods time, selection against insects that continuously produce a sound may lead to suppression or loss of that trait.

I am sure many of you have experienced the sound pollution produced by cicadas during the late spring and summer months. The tymbal, which is the sound producing organ in male cicadas unintentionally attracts Sarcophagid parasitoid flies. The fly oviposits a single egg in its cicada host that subsequently develops into a larva that is capable of destroying the tymbal. By destroying the tymbal, the fly larva reduces future host competition at the expense of the cicada, which loses the ability to attract females, and eventually dies when the larva emerges.

In the case of an introduced Australian cricket to Hawaii, chirping in males has been reduced because it attracts a nocturnal tachinid fly parasitoid (Ormia). Selective pressure by the parasitoid fly has favored a wing mutation in the crickets that prevents their ability to chirp and attract females. However, it is thought that males with the wing mutation may begin to behave like satellites of regular males that are capable of chirping and attracting females, so they could increase their reproductive success.

Posted by: Nelson Milano (2)