Male opportunistic mating increases with intensity of female sexual cannibalism in three web-building spiders

Sexual conflict is common in animals, and female sexual cannibalism represents an extreme form of sexual conflict. Males in many species have evolved a variety of strategies to circumvent or decrease the risk of female sexual cannibalism. Opportunistic mating, by which a male mates with a female when she is disturbed or when she is feeding or undertaking moulting, is one of such kinds of strategies, and widely occurs in many animals, especially in spiders. However, whether the occurrence of male opportunistic mating depends on the intensity of female sexual cannibalism remains largely unexplored. We predicted a positive correlation between them. In this study, we tested this prediction by performing a series of mating trials in the laboratory using three species of web-building spiders with different intensities of female sexual cannibalism: Nephila pilipes, Nephilengys malabarensis, and Parasteatoda tepidariorum. We found that the occurrence of male opportunistic mating was positively, though not statistically significantly, correlated with the intensity of female sexual cannibalism, thus supporting our hypothesis. All together, we provide evidence that male opportunistic mating may have evolved to respond to the selection pressure posed by female sexual cannibalism.

FGF signalling is involved in cumulus migration in the common house spider Parasteatoda tepidariorum

Cell migration is a fundamental component during the development of most multicellular organisms. In spiders, the collective migration of a signalling centre, known as the cumulus, is required to set the dorsoventral body axis of the embryo. Here, we show that FGF signalling plays an important role during cumulus migration in the spider Parasteatoda tepidariorum. Spider embryos with reduced FGF signalling lack cumulus migration and display dorsoventral patterning defects. Our study reveals that cumulus expression of several FGF signalling components is regulated by the transcription factor Ets4. In conjunction with a previous study, we show that the expression of fgf8 in the germ-disc is regulated via the Hedgehog signalling pathway. We also demonstrate that FGF signalling influences the BMP signalling pathway activity in the region around cumulus cells. Finally, we show that FGF signalling might also influence cumulus migration in basally branching spiders and we propose a hypothetical model in which fgf8 acts a chemo-attractant to guide cumulus cells towards the future dorsal pole of the spider embryo.

Does Only Egg Sac Protect Spider Embryos From Pathogens? Detection Of Antibacterial Proteins In Embryos of Theridiidae And Lycosidae Representatives

Cocoons covering spider embryos may constitute a physical barrier, protecting eggs from microbial infections. The aim of the study was to find out if the embryos have their own immune potential. We test the effect of cocoon deprivation on the level of antimicrobial proteins (AMPs) produced by spider embryos of Parasteatoda tepidariorum and Pardosa sp. Eggs in the age from 24 to 168 hours were divided in two experimental groups: C (closed, in untouched cocoon) and O (open, embryos isolated from the egg sac). Results indicate that the tested spiders embryos produce lysozyme, defensins and potentially other low-molecular-weight proteins with antimicrobial activity. Level of AMPs increased with the age of spider embryos. Lysozyme in both species was produced at a higher level than defensins. Deprivation of cocoon results in increased production of lysozyme only in Pardosa sp., which may be related to the specific type of parental care of lycosids.

Nasoniasegmentation is regulated by an ancestral insect segmentation regulatory network also present in flies

Insect segmentation is a well-studied and tractable system with which to investigate the genetic regulation of development. Though insects segment their germband using a variety of methods, modelling work implies that a single gene regulatory network can underpin the two main types of insect segmentation. This means limited genetic changes are required to explain significant differences in segmentation mode between different insects. Evidence for this idea is limited toDrosophila melanogaster, Tribolium castaneum, and the spiderParasteatoda tepidariorum, and the nature of the gene regulatory network (GRN) underlying this model has not been tested. Some insects, for exampleNasonia vitripennisandApis melliferasegment progressively, a pattern not examined in studies of this segmentation model, producing stripes at different times throughout the embryo, but not from a segment addition zone.Here we aim to understand the GRNs patterningNasoniausing a simulation-based approach. We found that an existing model ofDrosophilasegmentation (Clark, 2017) can be used to recapitulateNasonia’s progressive segmentation, if provided with altered inputs in the form of expression of the timer genesNν-caudalandNν-odd paired. We also predict limited topological changes to the pair rule network. Together this implies that very limited changes to theDrosophilanetwork are required to simulateNasoniasegmentation, despite the differences in segmentation modes, implying thatNasoniause a very similar version of an ancestral GRN also used byDrosophila.

The Evolution of Sox Gene Repertoires and Regulation of Segmentation in Arachnids

The Sox family of transcription factors regulates many processes during metazoan development, including stem cell maintenance and nervous system specification. Characterizing the repertoires and roles of these genes can therefore provide important insights into animal evolution and development. We further characterized the Sox repertoires of several arachnid species with and without an ancestral whole-genome duplication and compared their expression between the spider Parasteatoda tepidariorum and the harvestman Phalangium opilio. We found that most Sox families have been retained as ohnologs after whole-genome duplication and evidence for potential subfunctionalization and/or neofunctionalization events. Our results also suggest that Sox21b-1 likely regulated segmentation ancestrally in arachnids, playing a similar role to the closely related SoxB gene, Dichaete, in insects. We previously showed that Sox21b-1 is required for the simultaneous formation of prosomal segments and sequential addition of opisthosomal segments in P. tepidariorum. We studied the expression and function of Sox21b-1 further in this spider and found that although this gene regulates the generation of both prosomal and opisthosomal segments, it plays different roles in the formation of these tagmata reflecting their contrasting modes of segmentation and deployment of gene regulatory networks with different architectures.

Differences in Bifenthrin and Fipronil Susceptibility Among Invasive Latrodectus spp. (Araneae: Theridiidae) and Nontarget Spiders in Japan

Prompt responses to invasive Latrodectus spiders introduced unintentionally are needed worldwide due to their medical and ecological importance. Latrodectus species are chemically controlled using pyrethroid insecticides despite concerns about the ecological impacts of these compounds on biodiversity/ecosystems. Here, the relative sensitivities (acute toxicity: 48-h LC50) of Latrodectus hasseltii Thorell and Latrodectus geometricus C.L. Koch from Japan to the conventional neurotoxic insecticide bifenthrin (pyrethroid) and a new candidate insecticide, fipronil (phenylpyrazole), were examined. Acute residual toxicity tests of these compounds in two nontarget spiders (Parasteatoda tepidariorum C.L. Koch (Araneae: Theridiidae), Badumna insignis L. Koch (Araneae: Desidae)) were conducted for comparison. To test whether bifenthrin and fipronil toxicities differed among the four spiders, corresponding species sensitivity distributions (SSDs) were compared, and hazardous concentrations were determined. Sensitivity (especially in the nontarget species) was two to four orders of magnitude higher for bifenthrin than for fipronil. The SSD patterns of the two insecticides differed significantly, with the spider communities being more sensitive to bifenthrin than to fipronil. The lethal bifenthrin concentration for Latrodectus may reduce spider populations by over 70–90%. If L. hasseltii (established throughout Japan) is targeted for effective population suppression rather than L. geometricus (with a limited distribution range) using the specified insecticide concentration (LC50 value) for fipronil, less than 20% of spider communities will be impacted. Chemical operations aimed at the effective population management and subsequent eradication of invasive Latrodectus spiders while supporting local biodiversity conservation would benefit from considerations of fipronil dosages and target species sensitivities.

A preliminary information on spider fauna (Arachnida, Aranei) of the Fastiv district (Kyiv region)

In this article, an inventory of the spider fauna of the Fastov district of the Kiev region was carried out, an annotated list of spiders was compiled and includes 84 spider species of 67 genera from 20 families. The annotated list contains faunistic material, collection method and biotopic preferences of species. The most represented by the number of species in the fauna are the families Araneidae – 19 species (24 %), Thomisidae – 8 species (9 %) and Salticidae – 8 species (9 %). The dominance of species of the family Araneidae is due to the large proportion of the surveyed habitats and vegetation layers inhabited by orb weaving spiders. In general, widespread species of spiders with high ecological plasticity were prevail. Including 10 species: Clubiona caerulescens, Harpactea rubicunda, Haplodrassus silvestris, Zelotes electus, Diplostyla concolor, Tenuiphantes flavipes, Agroeca brunnea, Pardosa amentata, Pseudeuophrys erratica and Ozyptila praticola were recorded in the litter layer of a pine forest only. Three species: Cyclosa oculata, Oxyopes ramosus and Dolomedes plantarius are rare according to the literature data. Five species were found in near-water habitats: Larinioides cornutus, Clubiona phragmitis, D. plantarius, Tetragnatha extensa, and Marpissa radiata, and were not found in the other biotopes. Two species, Metellina segmentata and Tetragnatha montana, are found on near-water vegetation and forest edges. In buildings and in household plots, two synanthropic species were found – Tegenaria domestica and Parasteatoda tepidariorum. The zoogeographic and taxonomic compositions of the araneofauna of the region under study are presented. Arealogically, the basis is made up of the Palaearctic (35 %) and Holarctic (19 %) groups. West-Central-Palaearctic species – 14 %, European-Ancient Mediterranean – 12 %. European and more northern European-Siberian species account for 8 and 5 %, respectively. In comparison with the data for Polesie, the araneofauna of the Fastov region has certain characteristics, namely: a large participation in the composition of the araneofauna of Palaearctic and Holarctic species, a decrease in the proportion of EuropeanSiberian species and an increase in the proportion of European-Ancient Mediterranean groups of species.

Keanekaragaman Musuh Alami Koloni Lepidotrigona terminata Smith (Hymenoptera: Apidae: Meliponinae)

The research about types of natural enemies of stinless bees Lepidotrigona terminata had been conducted in West Java. All natural enemis were identified morphologically and their habitat. There were 687 individuals of 14 species of natural enemies obtained in this research, i.e., Pseudeuophrys sp., Heliophanus sp., Argiope versicolor, Plexippus paykuli, Marpissa sp., Parasteatoda tepidariorum, Tegenaria sp., Nasutitermes javanicus, Paratrechina sp., Polyrhachis sp., Paratrechina longicornis, Rhynchium haemorrhoidale, Hemidactylus frenatus and Hemidactylus garnotii. Based on observation, spider, ants, and lizard were the predators of stingless bee. The results are expected as data and knowledge in the conservation and cultivation of stingless bees.

The common house spider, Parasteatoda tepidariorum, maintains silk gene expression on sub-optimal diet

Cobweb weaving spiders and their relatives spin multiple task-specific fiber types. The unique material properties of each silk type result from differences in amino acid sequence and structure of their component proteins, primarily spidroins (spider fibrous proteins). Amino acid content and gene expression measurements of spider silks suggest some spiders change expression patterns of individual protein components in response to environmental cues. We quantified mRNA abundance of three spidroin encoding genes involved in prey capture in the common house spider, Parasteatoda tepidariorum (Theridiidae), fed different diets. After 10 days of acclimation to the lab on a diet of mealworms, spiders were split into three groups: (1) individuals were immediately dissected, (2) spiders were fed high-energy crickets, or (3) spiders were fed low-energy flies, for 1 month. All spiders gained mass during the acclimation period and cricket-fed spiders continued to gain mass, while fly-fed spiders either maintained or lost mass. Using quantitative PCR, we found no significant differences in the absolute or relative abundance of dragline gene transcripts, major ampullate spidroin 1 (MaSp1) and major ampullate spidroin 2 (MaSp2), among groups. In contrast, prey-wrapping minor ampullate spidroin (MiSp) gene transcripts were significantly less abundant in fly-fed than lab-acclimated spiders. However, when measured relative to Actin, cricket-fed spiders showed the lowest expression of MiSp. Our results suggest that house spiders are able to maintain silk production, even in the face of a low-quality diet.