"Long before it's in the papers"
January 27, 2015


“Maternal instincts” seen in group of colorful beetles

Sept. 27, 2013
Courtesy of Pensoft Publishers 
and World Science staff

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.

Larvae of the spe­cies Dory­phora pay­kulli move am­ong leaves, fol­lowed by their mot­her, in Pa­na­ma. (Credit: S. Van Bael)

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 scien­tists. 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.

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A group of related, colorful beetles in the thick foliage of tropical forests shows signs of maternal instincts and care, scientists say. In a report, researchers described different degrees of maternal instincts 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. 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. Beetle mothers in two species 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 an observer put a thin stick in the area, they wrote. Charges, stamping and shaking continued for some time after the stimulus was removed. A camera held 10 cm (4 inches) under and to the side of the “natal leaf” got the strongest reaction, they wrote. 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.