Offspring size is a fundamental trait in disparate biological fields of study. This trait can be measured as the size of plant seeds, animal eggs, or live young, and it influences ecological interactions, organism fitness, maternal investment, and embryonic development. Although multiple evolutionary processes have been predicted to drive the evolution of offspring size, the phylogenetic distribution of this trait remains poorly understood, due to the difficulty of reliably collecting and comparing offspring size data from many species. Here we present a database of 10,449 morphological descriptions of insect eggs, with records for 6,706 unique insect species and representatives from every extant hexapod order. The dataset includes eggs whose volumes span more than eight orders of magnitude. We created this database by partially automating the extraction of egg traits from the primary literature. In the process, we overcame challenges associated with large-scale phenotyping by designing and employing custom bioinformatic solutions to common problems. We matched the taxa in this database to the currently accepted scientific names in taxonomic and genetic databases, which will facilitate the use of this data for testing pressing evolutionary hypotheses in offspring size evolution.
The evolution of organism size is hypothesized to be predicted by a combination of development, morphological constraints, and ecological pressures. However, tests of these predictions using phylogenetic methods have been limited by taxon sampling. To overcome this limitation, we generated a database of more than ten thousand observations of insect egg size and shape from the entomological literature and combined them with published genetic and novel life-history datasets. This enabled us to perform phylogenetic tests of long-standing predictions in size evolution across hexapods. Here we show that across eight orders of magnitude in egg volume variation, the relationship between egg shape and size itself evolves, such that predicted universal patterns of scaling do not adequately explain egg shape diversity. We test the hypothesized relationship between size and development, and show that egg size is not correlated with developmental rate across insects, and that for many insects egg size is not correlated with adult body size either. Finally, we show that the evolution of parasitism and aquatic oviposition both help to explain the diversification of egg size and shape across the insect evolutionary tree. Our study challenges assumptions about the evolutionary constraints on egg morphology, suggesting that where eggs are laid, rather than universal mathematical allometric constants, underlies egg size and shape evolution.
The longhorn beetle genus Callipogon Audinet-Serville represents a small group of large wood-boring beetles whose distribution pattern exhibits a unique trans-Pacific disjunction between the East Asian temperate rainforest and the tropical rainforest of the Neotropics. To understand the biogeographic history underlying this circum-Pacific disjunct distribution, we reconstructed a molecular phylogeny of the subfamily Prioninae with extensive sampling of Callipogon using multilocus sequence data of 99 prionine and four parandrine samples (ingroups), together with two distant outgroup species. Our sampling of Callipogon includes 18 of the 24 currently accepted species, with complete representation of all species in our focal subgenera. Our phylogenetic analyses confirmed the purported affinity between the Palearctic Callipogon relictus and its Neotropical congeners. Furthermore, based on molecular dating under the fossilized birth–death (FBD) model with comprehensive fossil records and probabilistic ancestral range reconstructions, we estimated the crown group Callipogon to have originated in the Paleocene circa 60 million years ago (Ma) across the Neotropics and Eastern Palearctics. The divergence between the Palearctic C. relictus and its Neotropical congeners is explained as the result of a vicariance event following the demise of boreotropical forest across Beringia at the Eocene-Oligocene boundary. As C. relictus represents the unique relictual species that evidentiates the lineage's expansive ancient distribution, we evaluated its conservation importance through species distribution modelling. Though we estimated a range expansion for C. relictus by 2050, we emphasize a careful implementation of conservation programs towards the protection of primary forest across its current habitats, as the species remains highly vulnerable to habitat disturbance.
Whole-genome amplification by multiple displacement amplification (MDA) is a promising technique to enable the use of samples with only limited amount of DNA for the construction of RAD-seq libraries. Previous work has shown that, when the amount of DNA used in the MDA reaction is large, double-digest RAD-seq (ddRAD) libraries prepared with amplified genomic DNA result in data that are indistinguishable from libraries prepared directly from genomic DNA. Based on this observation, here we evaluate the quality of ddRAD libraries prepared from MDA-amplified genomic DNA when the amount of input genomic DNA and the coverage obtained for samples is variable. By simultaneously preparing libraries for five species of weevils (Coleoptera, Curculionidae), we also evaluate the likelihood that potential contaminants will be encountered in the assembled dataset. Overall, our results indicate that MDA may not be able to rescue all samples with small amounts of DNA, but it does produce ddRAD libraries adequate for studies of phylogeography and population genetics even when conditions are not optimal. We find that MDA makes it harder to predict the number of loci that will be obtained for a given sequencing effort, with some samples behaving like traditional libraries and others yielding fewer loci than expected. This seems to be caused both by stochastic and deterministic effects during amplification. Further, the reduction in loci is stronger in libraries with lower amounts of template DNA for the MDA reaction. Even though a few samples exhibit substantial levels of contamination in raw reads, the effect is very small in the final dataset, suggesting that filters imposed during dataset assembly are important in removing contamination. Importantly, samples with strong signs of contamination and biases in heterozygosity were also those with fewer loci shared in the final dataset, suggesting that stringent filtering of samples with significant amounts of missing data is important when assembling data derived from MDA-amplified genomic DNA. Overall, we find that the combination of MDA and ddRAD results in high-quality datasets for population genetics as long as the sequence data is properly filtered during assembly.
Light pollution on ecosystems is a growing concern, and knowledge about the effects of outdoor lighting on organisms is crucial to understand and mitigate impacts. Here we build up on a previous study to characterize the diversity of all beetles attracted to different commonly used streetlight set ups. We find that lights attract beetles from a broad taxonomic and ecological spectrum. Lights that attract a large number of insect individuals draw an equally high number of insect species. While there is some evidence for heterogeneity in the preference of beetle species to different kinds of light, all species are more attracted to some light radiating ultraviolet. The functional basis of this heterogeneity, however, is not clear. Our results highlight that control of ultraviolet radiation in public lighting is important to reduce the number and diversity of insects attracted to lights.
Weevils are one of the largest groups of living organisms, with more than 60,000 species feeding mostly on plants.With only one exception, their described larvae are typical plant-feeders, with mouthparts adapted to chewing plant material. Here we describe the second case of a weevil with early-instar larvae adapted to killing conspecifics.We have studied the life history of Anchylorhynchus eriospathae G. G. Bondar, 1943 (Curculioninae:Derelomini sensu Caldara, Franz&Oberprieler (2014)), a species whose immatures feed internally on palm flowers and fruits.We provide detailed descriptions of all immature stages, including the extremely modi- fied first-instar larva. Unlike other weevils and later instars, this stage exhibits a flat bodywith very long ventropedal lobe setae, a large and prognathous headwith a gula, and falciformmandibles, eachwith a serrate retinaculum, that are used to fightwith and eventually kill other first-instar larvae.We also provide biological notes on all stages and the results of behavioral tests that showed that larval aggression occurs only among early life stages. Finally we show that adult size is highly dependent on timing of oviposition. This specialized killer first instar probably evolved indepen- dently fromthe one other case known inweevils, in Revena rubiginosa (Conoderinae: Bariditae sensu Prena, Colonnelli&Hespenheide (2014)). Interestingly, both lineages inhabit the same hosts, raising the possibility that both intra- and inter-specific competition shaped those phenotypes. Given the scarcity of knowledge on early larval stages of concealed insect herbivores, it is possible that our findings represent an instance of amuch broader phenomenon. Our observations also allowed us to conclude that Anchylorhynchus eriospathae and A. hatschbachi G. G. Bondar, 1943 are actually the same species,whichwe synonymize here by considering the latter as a junior synonym(newsynonymy).
Anchylorhynchus vanini sp. nov. from the Amazon is described, including the mouthparts and male genitalia. The new species is compared with similar species within the genus and the key to the species of Anchylorhynchus provided by Vaurie (1954) is modified to include the new species. Adult specimens were collected in flowers of the palm Syagrus vermicularis Noblick and additional collections in other palms species suggest that this association is specific. This is the first record of the palm Syagrus vermicularis as host for a species of Anchylorhynchus.
Sicoderus robini sp. nov. (type locality: Bolivia, Santa Cruz de la Sierra, Buena Vista, El Cairo) is described and illustrat- ed. The new species is assigned to the Sicoderus appendiculatus species group, compared with similar species of the group and with the two other species of Sicoderus that occur in Bolivia. The previously published key for species identification of the S. appendiculatus group is updated to include the new species.
Three new species of the genus Anchylorhynchus from Colombia, are described: Anchylorhynchus pinocchio sp. nov., A. centrosquamatus sp. nov. and A. luteobrunneus sp. nov.. A morphological description, including the male genitalia, is pro- vided for each species as well as a comparison with similar species within the genus. All three species are found in inflo- rescences of species of Syagrus Mart. (Arecaceae). The adults are pollinators and the larvae develop inside fruits and feed on the endosperm, interrupting seed formation and causing fruit abortion.
Light pollution due to exterior lighting is a rising concern. While glare, light trespass and general light pollution have been well described, there are few reported studies on the impact of light pollution on insects. By studying insect behavior in relation to artificial lighting, we suggest that control of the UV component of artificial lighting can significantly reduce its attractiveness, offering a strong ability to control the impact on insects. Traditionally, the attractiveness of a lamp to insects is calculated using the luminous efficiency spectrum of insect rhodopsin. This has enabled the development of lamps that emit radiation with wavelengths that are less visible to insects (that is, yellow lamps). We tested the assumption that the degree of visibility of a lamp to insects can predict its attractiveness by means of experimental collections. We found that the expected lamp’s visibility is indeed related to the extent to which it attracts insects. However, the number of insects attracted to a lamp is disproportionally affected by the emission of ultraviolet radiation. UV triggers the behavior of approaching lights more or less independently of the amount of UV radiation emitted. Thus, even small amounts of UV should be controlled in order to develop bug-free lamps.
Background Traditionally, epidemiologists have considered electrification to be a positive factor. In fact, electrification as well as plumbing are typical initiatives that represent the integration of an isolated population into modern society, ensuring the control of pathogens and promoting public health. Nonetheless, electrification is always accompanied by night lighting, which attracts insect vectors and changes people's behavior. Although this may lead to new modes of infection and increased transmission of insect-borne diseases, the role of night lighting is rarely considered in epidemiological surveys. Objectives This paper reviews evidence concerning the role of lighting in the spread of diseases as documented in epidemiological literature, in order to encourage other researchers to consider this element in future studies. Discussions We present three case studies of infectious vector-borne diseases (Chagas, leishmaniasis, and malaria) and discuss evidence which suggests that use of artificial lighting results in behavioral changes and changes in the prevalence of vector species and modes of transmission. Conclusion Despite a surprising lack of studies, we conclude that existing evidence supports our hypothesis that artificial lighting leads to a higher risk of infection with vector-borne diseases. We believe that this is not only related to the simple attraction of traditional vectors to light sources, but also to changes in the behavior of both humans and insects that result in new modes of disease transmission. Considering the ongoing expansion of night lighting in developing countries, additional research on this subject is urgently needed.
The development of alternative energy sources and the increase in the efficiency of artificial lighting systems are allowing for the widespread diffusion of artificial lighting in isolated areas. Since many insects are strongly attracted by artificial lighting, we hereby launch hypotheses on the possible impact of the rising increase in the use of artificial lighting on the diffusion of diseases. Herein are also presented the results of attraction tests with different wavelengths of light radiation, indicating means of minimizing impacts.