G. it. Ent., 9 (48): 3-25
December 31, 1998
Torneutini (Coleoptera: Cerambycidae) of Argentina. Part 2.
Biology of Coccoderus novempunctatus (Germar, 1824),
Diploschema rotundicolle (Serville, 1834) and
Praxithea derourei (Chabrillac, 1857)
by
OSVALDO R. DI IORIO
Abstract - The tunnels bored by the larvae of Coccoderus novempunctatus, Diploschema rotundicolle and Praxithea derourei follow a way, from the apexes of branches to the bases of living plants. Last instar larvae of Coccoderus novempunctatus bore a circular or helicoidal tunnel just under the bark; they will build the pupal chamber in the dried branch above this. This behaviour varies according to the habitus of host plants (tree or shrub), a factor affecting the density of larvae per plant. Breakage of branches with last-instar larva circular tunnels is related to the hardness of wood of the host plant species. Larvae of Diploschema rotundicolle attain high densities infesting trees of Melia azedarach; they bore circular tunnels in the first instar, and rarely or never bore circular tunnels in the last one. Two new larval host plants for C. novempunctatus and three for Praxithea derourei are added to those known from Argentina and Brazil. The possible relation between defensive chemical substances (triterpenoids and limonoids) and host plant selection by the Torneutini in exotic and autochthonous Meliaceae is discussed.
