Being male doesn't usually generate a lot of respect or status in the insect world. At worst, a male preying mantis can have his head chomped off by his mate, and some male spiders are devoured by less than devoted females. At best, male insects are merely tolerated and thoroughly dominated by females.

But now a University of Washington researcher has discovered the first species among social insects, a wasp, where males rule the nest, biting and sometimes chasing off females, including their queens. They also consume much of the food gathered by workers.

Sean O'Donnell, the UW assistant professor of psychology who studied the wasps in the cloud forests of Costa Rica, believes more examples of male dominance among social insects will be found as researchers focus on the tropics where most species live. In the past, researchers, who primarily live in temperate zones, have studied social insects that live nearby and where male dominance doesn't exist.

"Among social insects males just haven't received much attention. We have had the bias that males are not important and, to some extent, we have ignored them," said O'Donnell, whose discovery will be published in the journal Ethology.

That probably is about to change following his study of the species Mischocyttarus mastigorphorus, which lives at about 1,450 meters elevation in the cloud forests of Costa Rica and neighboring countries. The wasp, which is about half an inch long, lives in small colonies of two to three dozen individuals in dark and dank conditions. It comes in two color types that mimic other wasp species living on the margins of its habitat, and males frequently make up half or more of a colony's population.

O'Donnell studied 32 colonies of M. mastigorphorus, surveying the number of males present in each and collected detailed behavioral data on six of the colonies, tracking all individuals.

Dominance behavior or aggressive social
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Contact: Joel Schwarz
joels@u.washington.edu
206-543-2580
University of Washington
8-Feb-1999