Beetle larvae that cooperate to mimic amorous bees 

Hafernik and Saul-Gershenz (2000) found that cooperative behaviour in insects is not limited to the social insects such as bees. He found that the larvae of a certain blister beetle, Meloe franciscanus (Meloidae) also does it.

Young larvae (triungulins) of the blister beetle have a remarkable system of finding a bee host, Habropoda pallida (Anthophoridae). The beetle larvae aggregate together on the vegetation and mimic the appearance of a female bee. Male bees confuse the larvae aggregate for a female and attempt to mate. This results in the larval aggregation attaching to the underside of the male. When the male finally finds a female and mates, the beetle larvae transfer themselves to the female and get transported back to the nest where they feed on the pollen collected by the female for her offspring.

 

Images provided by J. Hafernik. (These species do not occur in southern Africa but they illustrate yet another fascinating mimicry system in nature). Larvae of the blister beetle Meloe franciscanus aggregate on the end of plant stems to mimic the appearance of female Habropoda pallida.  

 

Male bees pick up larvae from stems through pseudocopulation and then deposit the larvae on female bees during mating attempts. Close-up of triungulin larvae on the underside of a male bee.  

Female bee with triungulin larvae on her back. These larvae are the result of venereal transmission from a male bee.

 

Not only does the aggregation of beetle larvae look like the female bee but it was deduced that pheromones were also emitted by the larvae as male bees were observed to land and hover next to groups of larvae before they aggregated. Painted models of the aggregations were also placed nearby and these were ignored by the male bees.

The question is why has this Meloe species of blister beetle developed a system such as this? Hafernik and Saul-Gershenz point out that Meloe species produce large clutches of larvae (about 3000) and this is associated with high larval mortality. The study site was situated in a desert region so it would seem that the mimicry system developed by M. franciscanus enhances its survival in a harsh environment where bee numbers, flowers and flowering frequency are highly variable.

In his research on Fideliidae bees in South Africa, V. B. Whitehead of the South African Museum found Sitaris sp. (Meloidae) larvae on bees, Fidelia paradoxa (Fideliidae). The beetle larvae in this case merely transfer singly from the flowers onto the bees and then drop off in the bee nest.

Reference

  • Hafernik, J. and Saul-Gershenz, L. 2000. Beetle larvae cooperate to mimic bees. Nature. Vol. 405. 4 May: 35.

Page by Margie Cochrane


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