Single chambered heart is present in which insect order?

Solution(By Examveda Team)

The single chambered heart is present in Mallophaga and Anoplura insect order.
The number of chambers in an insect heart varies with grasshoppers having eight, for instance, and cockroaches a whopping thirteen. Each chamber of the heart has two holes called ostia. These have valves so that blood only flows one way from the pool of haemolymph in the body into the heart.
The circulatory system is an open one, with most of the body fluid, or hemolymph, occupying cavities of the body and its appendages.