28 research outputs found
Monogamous sperm storage and permanent worker sterility in a long-lived ambrosia beetle
The lifetime monogamy hypothesis claims that the evolution of permanently unmated worker castes always requires maximal full-sibling relatedness to be established first. The long-lived diploid ambrosia beetle Austroplatypus incompertus (Schedl) is known to be highly social, but whether it has lifetime sterile castes has remained unclear. Here we show that the gallery systems of this beetle inside the heartwood of live Eucalyptus trees are always inhabited by a single core family, consisting of a lifetime-inseminated mother, permanently unmated daughter workers, and immatures that are always full siblings to each other and their adult caretakers. Overall sex ratios are even. Males always disperse and only survive as stored sperm, but female offspring either disperse to mate and found their own colony or assume unmated worker roles, probably surviving for many years without any reproductive potential because tarsal loss precludes later dispersal. A well-supported Platypodinae phylogeny has allowed us to infer that parental monogamy evolved before a lifetime-unmated worker caste emerged, confirming the prediction that monogamy and full-sibling relatedness are necessary conditions for the evolution of such workers. The initially very challenging but ultimately long-term stable nesting habitat in live trees appears to have provided the crucial benefit/cost factor for maintaining selection for permanently sterile workers after strict monogamy and lifetime sperm storage had become established in this curculionid coleopteran lineage
New species of Ophiostomatales from Scolytinae and Platypodinae beetles in the Cape Floristic Region, including the discovery of the sexual state of Raffaelea
Olea capensis and Rapanea melanophloeos
are important canopy trees in South African
Afromontane forests. Dying or recently dead individuals
of these trees are often infested by Scolytinae and
Platypodinae (Curculionidae) beetles. Fungi were
isolated from the surfaces of beetles emerging from
wood samples and their galleries. Based on micromorphological
and phylogenetic analyses, four fungal
species in the Ophiostomatales were isolated. These were Sporothrix pallida and three taxa here newly
described as Sporothrix aemulophila sp. nov., Raffaelea
vaginata sp. nov. and Raffaelea rapaneae sp. nov.
This study represents the first collection of S. pallida, a
species known from many environmental samples
from across the world, from Scolytinae beetles. S.
aemulophila sp. nov. is an associate of the ambrosia
beetle Xyleborinus aemulus. R. rapaneae sp. nov. and
R. vaginata sp. nov. were associated with a Lanurgus
sp. and Platypodinae beetle, respectively, and represent
the first Raffaelea spp. reported from the Cape
Floristic Region. Of significance is that R. vaginata
produced a sexual state analogous with those of Ophiostoma seticolle and O. deltoideosporum that
also grouped in our analyses in Raffaelea s. str., to date
considered an asexual genus. The morphology of the
ossiform ascospores and anamorphs of the three
species corresponded and the generic circumscription
of Raffaelea is thus emended to accommodate sexual
states. The two known species are provided with new
combinations, namely Raffaelea seticollis (R.W.
Davidson) Z.W. de Beer and T.A. Duong comb. nov.
and Raffaelea deltoideospora (Olchow. and J. Reid)
Z.W. de Beer and T.A. Duong comb. nov.DST/NRF Centre of Excellence in Tree Health Biotechnology (CHTB).http://link.springer.com/journal/104822016-10-30hb201