Entomologists from Panama, Europe, Canada and Brazil have teamed up to describe in detail the different degrees of maternal instincts present within eight species of the colorful leaf beetles from Central and South America.

According to their study published in the open-access journal ZooKeys, within the leaf beetles, maternal care of offspring is found in just two of 15 subfamilies – the broad-shouldered leaf beetles, Chrysomelinae, and the tortoise beetles, Cassidinae, groups possibly more vulnerable to predators and parasitoids due to slow-moving and exposed immature stages.

Complex subsocial behavior was observed in pairs of one of the species studied, Doryphora paykulli, interacting aggressively on newly expanded leaves. Whether these were contests over resources or precopulatory courtship is unclear, however, analysis of video taken of one of these interactions shows the use of the mesosternal horn in dislodging a competitor. Adult females of Doryphora paykulli were discovered during mid-May in close proximity to eggs attached to the cupped apical leaves.

Observations of additional species associated with a different family of plants, the Solananceae, suggest that mothers modify leaf resources in advance of bearing live offspring, and later block and herd movement of larvae among leaves on the same food plant. An adult was also recorded following a tightly arranged group of larvae moving between leaves on their food plant. Mothers at times tightly straddled their aggregated first and second instar larvae on the natal leaf, preventing their advance down the leaf petiole.

While guarding, mothers reacted aggressively by charging to the edge of the leaf when a thin stick was introduced to the area by an observer. Charges, stamping and shaking continued for a short period of time after the stimulus was removed. The strongest reaction was given to a camera held approximately 10 cm under and to the side of the natal leaf.

Reports on the three Doryphora species that feed on vines in the dogbane family, Apocyanaceae, reveal that mothers defend eggs and larvae by straddling, blocking access at the petiole and greeting potential predators with leaf-shaking and jerky advances.

A less aggressive form of maternal care is found in two Platyphora and four Proseicela species associated with shrubs and small trees in the nightshade family Solanaceae.

“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,” said lead author Dr Donald Windsor from the Smithsonian Tropical Research Institute in Panama.

“We urge continued study of these magnificent insects, their enemies and their defenses, both behavioral and chemical, especially in forests along the eastern versant of the Central and South American cordillera.”

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Bibliographic information: Windsor DM et al. 2013. Subsocial Neotropical Doryphorini (Chrysomelidae, Chrysomelinae): new observations on behavior, host plants and systematics. In: Jolivet P, Santiago-Blay J, Schmitt M (Eds). Research on Chrysomelidae 4. ZooKeys 332: 71 – 93; doi: 10.3897/zookeys.332.5199