Wednesday, March 30, 2011

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)

2 comments:

  1. i'm not really familiar with insect life or anatomy, but does this mean that they need to sing to survive? or that they need to sing to reproduce?

    or is it the other way around? they need to be quiet?


    Cleopatra Duque

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  2. Different insects use different methods to attract the opposite sex, so they could reproduce and maintain the survival of their species. These methods of attraction include pheromones, displays, wing vibration sensing organs, and in this case singing (sometimes they involve a combination of them). The selective pressure towards cicadas and Australian crickets by parasitoid flies acts on their main method for attracting mates. With the crickets, the only males that were surviving for reproduction were ones with wing mutations that simply made them mute. What is suggested is that mute mails follow the songs produced by regular males to gain access to females. So all three (regular males, mutated males and females) may be needed for this cricket species to survive in Hawaii (regular males to attract females and mutated males to mate multiple times).

    I am pretty sure this could’ve been said in fewer words, but I hope it clarifies things for you.

    Posted by: Nelson Milano

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