Dietary specialization in European species groups of seed beetles (Coleoptera: Bruchidae: Bruchinae)

Abstract

Because of their particular biology, seed beetles exhibit a strong relationship with their larval host plants. In Europe, however, field data have long been scarce and unreliable. The results of Legume seed collections of nearly 1,000 samples belonging to 292 species from various locations in Europe are summarized. The status of current Bruchidius species groups is amended on morphological and phylogenetic bases. Recent advances in the knowledge of phylogenetic structures of both Fabaceae and Bruchinae provide a new picture of Bruchinae-Fabaceae interactions. It reveals a certain level of host conservatism. The hypothesis of radiative adaptation seems the most compatible with observed data.

New seed beetles from Thailand belonging to the Bruchidius mendosus (Gyllenhal, 1839) species-group, and a key to Southeast Asian species (Coleoptera, Chrysomelidae: Bruchinae)

“…However, purely morphological arguments in favour of this hypothesis are very strong: small size of the adult, which fi ts the usually very small size of Desmodieae seeds; elytral pattern similar to that found in several other species, particularly in B. meibomiaca, a species that feeds in Dendrolobium umbellatum seeds in India and Vietnam (Delobel 2010b); ornamentation of saccus consisting in a small number of dented sclerites and spines (usually 2 to 4 in Asian Desmodieae-feeding bruchines). However, the peculiar shape of the ventral valve in B. aereomaculatus sheds a doubt on its inclusion in the Desmodieae-feeding group of species.…”

“…Th e number of species presently known to share this common larval diet in Asia is estimated to be about twenty, of which sixteen were recorded in Vietnam (Delobel 2014). Several more Indian species, estimated to be at least ten (Delobel 2010b) show similar morphological features, and possibly belong to the same group of species. Apart from their small size, males of the group are best characterized by internal sac ornamentation, with variously arranged sclerotised teeth, and a small number (two to four) of usually dented plates.…”

“…In some cases however, examination of genitalia will be found necessary. It is based on a key previously published for Vietnam (Delobel 2010b), to which are added species reported posteriorly. Our current knowledge of the geographic distribution of these 20 species is given in brackets.…”

“…A number of seed beetles closely related with the paleotropical species Bruchidius mendosus (Gyllenhal, 1839) were described from India (Arora 1977, Sri Lanka (Decelle 1975) and Vietnam (Delobel 2010a(Delobel , b, 2014. Th ey are small to very small beetles, oft en measuring less than 1.5 mm in length, and all those with known host plant feed in the seeds of Fabaceae Desmodieae.…”

Applied evolutionary ecology of insects of the subfamily Bruchinae (Coleoptera: Chrysomelidae)

“…Proximate mechanisms for host-plant shifts are probably associated with chemical (Janzen, 1969), morphological (Janzen, 1969;Szentesi and Jermy, 1995) and geographical (Johnson and Siemens, 1991) proximity between the current and potential hosts. Delobel and Delobel (2006) suggest that the speciation in European bean beetles is sequential evolution 338 M. TUDA The genera in bold include pest species.…”