Timing and host plant associations in the evolution of the weevil tribe Apionini (Apioninae, Brentidae, Curculionoidea, Coleoptera) indicate an ancient co-diversification pattern of beetles and flowering plants

New basal taxa of South African Apioninae (Coleoptera: Curculionoidea: Brentidae)

Four new genera, six new species and one new subspecies of the brentid subfamily Apioninae are described from the Republic of South Africa (R.S.A.), all representing ancient fauna with Gondwanan roots. The new genera are: Rhynchitapion gen. n., with Rh. variiforme sp. n. (the type-species) and Rh. pallidum sp. n., Apodytapion gen. n., with A. stepniewskii sp. n., Turnerapion gen. n., with T. pondoense sp. n., and Lepanomidius gen. n., with L. ruthmuellerae sp. n. (the type-species) and L. magdaloides sp. n. The primitive genus Lepanomus Balfour-Browne is re-described and a new subspecies of its type species, Lepanomus crinalis zuluensis ssp. n., is described from north-eastern R.S.A. In addition, Rhynchitapion usambarense sp. n. is described from Tanzania. An identification key to all 12 basal genera of South African Apioninae is presented and their higher systematics is discussed. Three new tribes are proposed in South African Apioninae: Rhynchitapiini trib. n., Apodytapiini trib. n., and Lepanomini trib. n., in addition to the existing basal Antliarhinini Schoenherr, 1823, Tanaini Schoenherr, 1839, Mecolenini Wanat, 2001, Apiomorphini Legalov, 2018, Setapiini Legalov, 2018, and derived Apionini Schoenherr, 1823. A temporary resignation from supertribal division of the subfamily is recommended after discussion.

Patterns of host tree use within a lineage of saproxlic snout-less weevils (Coleoptera: Curculionidae: Scolytinae: Scolytini)

The influence of plants in the diversification of herbivorous insects, specifically those that utilize moribund and dead hosts, is little explored. Host shifts are expected because the effectiveness of toxic secondary chemicals is lessened by decay of dead plants. Feeding on dead plants also releases herbivorous insect lineages from diversifying within a particular plant lineage. Thus, phylogenetic constraints on the herbivorous insect lineage imposed by the host plants are diminished and repeated patterns of species diversification in an association with unrelated host trees is hypothesized (i.e., taxon cycle). Scolytini, a diverse weevil tribe, specialize on many different dead and moribund plant taxa as a source of food. These species and their hosts offer an opportunity to examine the association between dead host plants and the extent of phylogenetic constraints. A phylogeny of the Scolytini was reconstructed with likelihood and Bayesian analyses of DNA sequence data from nuclear (28S, CAD, ArgK) and mitochondrial (COI) genes. Ancestral host usage and geography was reconstructed using likelihood criteria and conservation of host use was tested. Results supported a monophyletic Scolytini, Ceratolepis, Loganius, and a paraphyletic Scolytus, Camptocerus and Cnemonyx. Diversification of the Scolytini generally occurred well after their host taxa diversified and suggests a sequential evolution of host use. In this scenario the beetle imposes little selection pressure on the tree but the tree provides a platform for beetle evolution. Major changes in host tree use occurred during periods of global cooling associated with changes in beetle biogeography. Diversification of beetles occurred on common and widespread hosts and there was likely a single origination of conifer-feeding from angiosperm-feeding species during the early Pliocene and a radiation of beetle species from the Palearctic to the Nearctic. Overall, the observed patterns of Scolytini host use are conserved and are similar to those expected in a taxon pulse diversification. That is, after a host switch to an unrelated tree, the beetles diversify within the host plant lineage. The need to locate an ephemeral food resource, i.e., a dying tree, likely maintains host specificity once a host shift occurs. These findings suggest that characteristics of dead and moribund host plants (e.g. secondary chemicals) influence the diversification of these saproxlic weevils despite the reduction of selection pressures.

Genome-wide macroevolutionary signatures of key innovations in butterflies colonizing new host plants

The mega-diversity of herbivorous insects is attributed to their co-evolutionary associations with plants. Despite abundant studies on insect-plant interactions, we do not know whether host-plant shifts have impacted both genomic adaptation and species diversification over geological times. We show that the antagonistic insect-plant interaction between swallowtail butterflies and the highly toxic birthworts began 55 million years ago in Beringia, followed by several major ancient host-plant shifts. This evolutionary framework provides a valuable opportunity for repeated tests of genomic signatures of macroevolutionary changes and estimation of diversification rates across their phylogeny. We find that host-plant shifts in butterflies are associated with both genome-wide adaptive molecular evolution (more genes under positive selection) and repeated bursts of speciation rates, contributing to an increase in global diversification through time. Our study links ecological changes, genome-wide adaptations and macroevolutionary consequences, lending support to the importance of ecological interactions as evolutionary drivers over long time periods.

Species complex diversification by host plant use in an herbivorous insect: The source of Puerto Rican cactus mealybug pest and implications for biological control

Cryptic taxa have often been observed in the form of host‐associated species that diverged as the result of adaptation to alternate host plants. Untangling cryptic diversity in species complexes that encompass invasive species is a mandatory task for pest management. Moreover, investigating the evolutionary history of a species complex may help to understand the drivers of their diversification. The mealybug Hypogeococcus pungens was believed to be a polyphagous species from South America and has been reported as a pest devastating native cacti in Puerto Rico, also threatening cactus diversity in the Caribbean and North America. There is neither certainty about the identity of the pest nor the source population from South America. Recent studies pointed to substantial genetic differentiation among local populations, suggesting that H. pungens is a species complex. In this study, we used a combination of genome‐wide SNPs and mtDNA variation to investigate species diversity within H. pungens sensu lato to establish host plant ranges of each one of the putative members of the complex, to evaluate whether the pattern of host plant association drove diversification in the species complex, and to determine the source population of the Puerto Rican cactus pest. Our results suggested that H. pungens comprises at least five different species, each one strongly associated with specific host plants. We also established that the Puerto Rican cactus pest derives from southeastern Brazilian mealybugs. This is an important achievement because it will help to design reliable strategies for biological control using natural enemies of the pest from its native range.

The early wasp plucks the flower: disparate extant diversity of sawfly superfamilies (Hymenoptera: ‘Symphyta’) may reflect asynchronous switching to angiosperm hosts

The insect order Hymenoptera originated during the Permian nearly 300 Mya. Ancestrally herbivorous hymenopteran lineages today make up the paraphyletic suborder ‘Symphyta’, which encompasses c. 8200 species with very diverse host-plant associations. We use phylogeny-based statistical analyses to explore the drivers of diversity dynamics within the ‘Symphyta’, with a particular focus on the hypothesis that diversification of herbivorous insects has been driven by the explosive radiation of angiosperms during and after the Cretaceous. Our ancestral-state estimates reveal that the first symphytans fed on gymnosperms, and that shifts onto angiosperms and pteridophytes – and back – have occurred at different time intervals in different groups. Trait-dependent analyses indicate that average net diversification rates do not differ between symphytan lineages feeding on angiosperms, gymnosperms or pteridophytes, but trait-independent models show that the highest diversification rates are found in a few angiosperm-feeding lineages that may have been favoured by the radiations of their host taxa during the Cenozoic. Intriguingly, lineages-through-time plots show signs of an early Cretaceous mass extinction, with a recovery starting first in angiosperm-associated clades. Hence, the oft-invoked assumption of herbivore diversification driven by the rise of flowering plants may overlook a Cretaceous global turnover in insect herbivore communities during the rapid displacement of gymnosperm- and pteridophyte-dominated floras by angiosperms.

Frozen Antarctic path for dispersal initiated parallel host-parasite evolution on different continents

After the break-up of Gondwana dispersal of organisms between America, Australia and Africa became more complicated. One of the possible remaining paths led through Antarctica, that was not yet glaciated and it remained habitable for many organisms. This favourable climate made Antarctica an important migration corridor for organisms with good dispersal ability, such as Aculeata (Hymenoptera), till the Oligocene cooling. Here we tested how cooling of Antarctica impacted global dispersal of Aculeata parasites (Strepsiptera: Xenidae). Our data set comprising six nuclear genes from a broad sample of Xenidae. Bayesian dating was used to estimate divergence times in phylogenetic reconstruction. Biogeography was investigated using event-based analytical methods: likelihood-based dispersal-extinction-cladogenesis and Bayesian models. The Bayesian model was used for reconstruction of ancestral host groups. Biogeographical methods indicate that multiple lineages were exchanged between the New World and the Old World + Australia until the Antarctica became completely frozen over. During the late Paleogene and Neogene periods, several lineages spread from the Afrotropics to other Old World regions and Australia. The original hosts of Xenidae were most likely social wasps. Within one lineage of solitary wasp parasites, parallel switch to digger wasps (Sphecidae) occurred independently in the New World and Old World regions. The biogeography and macroevolutionary history of Xenidae can be explained by the combination of dispersal, lineage extinction and climatic changes during the Cenozoic era. A habitable Antarctica and the presence of now-submerged islands and plateaus that acted as a connection between the New World and Old World + Australia provided the possibility for biotic exchanges of parasites along with their hymenopteran hosts. Although Xenidae are generally host specialists, there were significant host switches to unrelated but ecologically similar hosts during their evolution. There is little or no evidence for cophylogeny between strepsipteran parasites and hymenopteran lineages.

A preliminary overview of the Brazilian Apioninae (Coleoptera: Brentidae) with an illustrated key for genera, and a checklist with distribution information

Abstract: Here we examine the taxonomic diversity of the Brazilian Apioninae (Coleoptera: Brentidae) and provide an update based on the literature and through examination of material in primary Brazilian collections. Ten genera and 89 species are valid and we include 30 (25 genera, 5 species) new distribution records. Chrysapion Kissinger, 1968 is first reported in Brazil, restricted to the northeast. Ranges now include the Amazon (three genera and one subgenus) and Atlantic (four genera and one subgenus) forests, the Pantanal (five genera) and Cerrado (three genera). The ranges of several genera now include more than one new biome. An identification key (including images of adults and illustrations of male genitalia) also includes the 10 Brazilian genera of Apioninae for the first time.

Climate and host-plant associations shaped the evolution of ceutorhynch weevils throughout the Cenozoic

Using molecular phylogenetic data and methods we inferred divergence times and diversification patterns for the weevil subfamily Ceutorhynchinae in the context of host‐plant associations and global climate over evolutionary time. We detected four major diversification shifts that correlate with both host shifts and major climate events. Ceutorhynchinae experienced an increase in diversification rate at ∼53 Ma, during the Early Eocene Climate Optimum, coincident with a host shift to Lamiaceae. A second major diversification phase occurred at the end of the Eocene (∼34 Ma). This contrasts with the overall deterioration in climate equability at the Eocene‐Oligocene boundary, but tracks the diversification of important host plant clades in temperate (higher) latitudes, leading to increased diversification rates in the weevil clades infesting temperate hosts. A third major phase of diversification is correlated with the rising temperatures of the Late Oligocene Warming Event (∼26.5 Ma); diversification rates then declined shortly after the Middle Miocene Climate Transition (∼14.9 Ma). Our results indicate that biotic and abiotic factors together explain the evolution of Ceutorhynchinae better than each of these drivers viewed in isolation.

Species delimitation within the Bothryorrhynchapion weevils: Multiple evidence from genetics, morphology and ecological associations

Curculionidae is a hyperdiverse group of beetles, whose taxonomy and phylogenetics are still poorly understood, especially at the genus level. The latest work on the evolution of Apionini showed a noticeable "mess" in the subtribe Oxystomatina, where most of the morphology-based genera were found to be polyphyletic or paraphyletic. These discrepancies between classical taxonomy and molecular phylogenetics implied the need for further taxonomic revision of these groups. Here, we used sets of morphological, molecular and ecological characters to verify the taxonomic statuses and disentangle the phylogenetic relations among the Bothryorrhynchapion apionids, which are classified as a subgenus of Cyanapion. Morphological data including morphometrics, and multilocus molecular analyses confirmed the monophyly of the Bothryorrhynchapion and species statuses of five species. The morphological analyses showed that Cyanapion (Bothryorrhynchapion) protractum (Sharp, 1891) from the southeast Palaearctic is a synonym of C. (B.) gyllenhalii (Kirby). Moreover, ecological features (host plant use and presence/absence of the endosymbiotic bacteria Wolbachia) helped to unravel the relations among the examined weevils. The speciation of Bothryorrhynchapion apionids was probably affected by allopatric distribution, shifts in the preferred host plants (Vicia sp. or Lathyrus sp.) of sympatric taxa, and infection by different strains of Wolbachia. The paper presents the first comprehensive description of the species' morphology, biology and ecology, and includes a key to the species.