Australian insects build houses to keep from drying out
3 October 2014 2:30 pm
Life is a major challenge for small animals living in the hot and dry Australian outback. Being small increases their risk of desiccation, and there are few options to deal with the constant hot and dry weather. At a mere 2 to 3 millimeters in length, thrips are among the smallest insects found on Australian soil, and they have evolved various ways to keep cool and avoid drying out. Their main strategy involves the formation of galls on various acacia plants. These galls—hollow knobby growths of plant tissue that swell in response to thrips—protect insects from the outside weather. Now, scientists have found a new antidesiccation strategy in a group of acacia thrips, according to a study published online before print in the journal Behavioral Ecology. Dunatothrips aneurae (pictured) build a tiny house made of the phyllodes (leaflike structures) of acacia trees, glued together by a silklike secretion extruded from the insect’s anus. This silken chamber keeps moisture levels high inside, stopping these minuscule insects from drying out. Although cozy, these homes are also fragile. The domicile wall often gets damaged by wind, and the thrips rush over to fix the damage so their offspring don’t dry or fall out. The discovery represents the first confirmed case of active parental care against desiccation in an insect. The finding may also represent a step in the evolution of social behavior in thrips, as domicile building is often a group affair. Domiciles can host groups of adults, which may be considered a kind of babysitting club, so if someone dies there are others to care for their babies, as happens in bees and termites.