Question

In the evening, males of a species of bee (Idiomelissodes duplocincta) form sleeping clusters in which dozens or hundreds of bees perch close together overnight. An assassin bug kills bees at these sleeping sites, but usually only one or two bees per night.

(A) The bees do not join forces to fight the bug when one appears, so it may be that a bee joins the cluster to dilute the risk that it will be one of the unlucky ones killed at random.

(B) The same sort of clustering of defenseless prey occurs in spadefoot frog tadpoles; hundreds of tadpoles swim and feed together in pools containing carnivorous water beetles that attack and kill them.

(C) In contrast, males of other bees in the genus Idiomelissodes are larger and more capable of deterring a predator on their own, and they sleep apart.

(D) The dilution effect hypothesis receives support from the observation that males of certain poisonous inedible flies do not form sleeping groups.

Answer 1

The sleeping clusters of Idiomelissodes duplocincta bees illustrate the dilution effect, where larger groups decrease individual predation risk, contrasting with other species that do not form clusters due to their size and ability to deter predators (option D).

Step-by-step explanation:

The sleeping clusters formed by the Idiomelissodes duplocincta species of bees serve as a way to dilute the individual risk of predation from predators such as the assassin bug. This concept, known as the dilution effect, suggests that the likelihood of any single individual being preyed upon is reduced when in a large grouping. This behavior contrasts with other species within the same genus which are larger and do not form clusters, indicating that the size and ability to deter predators can influence social behavior patterns among closely related species. The dilution effect is further supported by observations that certain poisonous and inedible flies do not form sleeping groups; since they are less vulnerable to predation due to their toxicity, there is less need for them to employ risk dilution strategies.

Hence, the answer is option D.