A group of related, colorful beetles in the thick foliage of tropical forests shows signs of maternal instincts and active care, scientists say.
In a report, researchers described “maternal” behaviors in eight species within a subfamily of leaf beetles known as broad-shouldered leaf beetles, or Chrysomelinae. The findings were published in a special issue of the research journal Zookeys.
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Larvae of the species Doryphora paykullimove among leaves, followed by their mother, in Panama. (Credit: S. Van Bael)
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Mothers “actively defend offspring” as well as the eggs, wrote the researchers, Donald M. Windsor of the Smithsonian Tropical Research Institute in Balboa-Ancon, Panama, and colleagues.
Maternal care in insects is rarely seen in such active forms, though common in lower-level forms such as insects positioning their eggs so the newborns will have access to a good food source.
Beetle mothers in two species within the Chrysomelinae group treated the leaf on which their youngsters were born as a sort of nest to be protected, the scientists found. The mothers reacted aggressively to invaders, and charged toward the edge the leaf when a person put a thin stick in the area, they wrote. Stamping and leaf-shaking were other common reactions, they added.
A camera held 10 cm (4 inches) under and to the side of the “natal leaf” got the strongest reaction, according to the scien-tists. Mothers also were found to “guard” larvae by straddling them.
Other species of beetles showed “less aggressive” forms of maternal care, they added. The scientists said some mothers seem to make changes to the leaves where their offspring are born. And once the young beetles, or larvae, are born, some mothers were described as “herding” them to make them go in desired directions and keep them together in little groups.
The investigators said it’s not clear why these behaviors evolved in these Central and South American beetles. “Large voids remain in our understanding of the natural history of both groups, including the identity and importance of predators and parasitoids and the diverse ways in which mothers may be influencing the survival of offspring,” Windsor and colleagues wrote.
