2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
Drones of the bee Habropoda pallida from the Mojave Desert (A) and Habropoda miserabilis from Oregon (B) with the larvae of the blister beetle Meloe franciscanus adhered to.
The Franciscan T-shirt (Meloe franciscanus) blister beetles, which parasitize bees, have adapted to the host species that lives in the same place as the beetles, according to the Proceedings of the National Academy of Sciences. Larvae from separate populations of beetles living in Oregon and the Mojave Desert, in the same area, together with the bees Habropoda miserabilis and Habropoda pallida, respectively, in order to attract males, learned to produce pheromones of females of a particular species of bees.
The flightless beetle Meloe franciscanus is native to North America. They parasitize on earthen bees - the female lays more than 700 eggs from which larvae hatch at the same time. All of them climb high grass, forming a single cluster, and at the same time produce pheromones, attracting males. After the male sits on the larvae, they grab onto him and he transfers them to the female bee. During mating, the larvae move from male to female, and she transfers them to the nest. There, the parasites grow, feeding on bee eggs and larvae, and next spring they leave the nest in the form of adults.
As the American entomologists led by Leslie Saul-Gershenz discovered in their previous work, the bee Habropoda pallida produces pheromones in the glands on the head. They are hydrocarbons with a chain length of 21 to 31 links, in one of the positions of which there is an unsaturated bond. Pheromones of females and males differ only in the position of this unsaturated bond. T-shirt larvae have learned to produce substances identical to the pheromones of females, and with their help lure drones.
In the new work, the researchers studied two isolated populations of M. franciscanus beetles in Oregon and the Mojave Desert. The same areas are inhabited by the earth bees Habropoda miserabilis and Habropoda pallida, on which they parasitize. Entomologists analyzed how beetles were able to adapt to different types of insect hosts. First, they studied how the drones of both types of bees react to females of their own species and to the larvae of beetles, as well as which part of the female's body attracted them the most. It turned out that most of all males were attracted by heads, and they did not react to the rest of the body of females and to other males.
Then the authors of the work obtained extracts from females and males of two species, as well as from larvae of Franciscan T-shirts, and analyzed their composition using gas chromatography-mass spectrometry. It turned out that in both cases, the larvae produced substances identical in composition to the pheromones of females, not males. It also turned out that blister beetles adapt not only by changing the composition of pheromones, but also by changing their behavior. The larvae of beetles living in Oregon, in search of bees, climb onto the grass 10-40 centimeters high, and the larvae from the Mojave Desert form clusters at a height of 2-12 centimeters.
Pheromones, which are produced by bees H. miserabilis and H. pallida and "local" larvae of blister beetles. The blue vertical line shows substances whose composition is identical in larvae and females, but absent in drones.
In conclusion, the researchers tested the reaction of male bees to larvae from a different population and showed that they prefer parasites from the local population, rather than "alien" individuals.
Earlier entomologists discovered that Varroa mites parasitizing honey bees not only develop a chemical "camouflage", but are also able to change its composition in a week to adapt to a new host.