Spolno vedenje pajkov vrste Caerostris darwini - Šuen, Klavdija (2019)
Vrsta pajka Caerostris darwini je znana po uporabi največjih kolesastih mrež, ki jih gradijo iz biološkega materiala, ki po natezni trdnosti presega vse ostale znane svile pajkov in celo večino sintetičnih vlaken. Nedavne publikacije poročajo tudi o spolnem velikostnem dimorfizmu, ki je običajno povezan z nenavadnim spolnim vedenjem, ki pa je pri tej vrsti skoraj popolnoma neznano. Zaradi tega smo opravili vedenjske raziskave na terenu na Madagaskarju in v kontroliranih laboratorijskih poskusih. Ugotovili smo, da je nabor spolnih vedenj C. darwini podoben kot pri ostalih spolno dimorfnih vrstah. Ta vedenja vključujejo preferenco samcev do parjenja s sveže levljeno, t.j. teneralno samico, poškodovanje spolnih organov med paritvijo in spolni kanibalizem. Dvorjenje samcev je bilo intenzivno in je vključevalo vezanje samice s svilo. Pri dvorjenju smo opazili tudi do sedaj neznano spolno vedenje, ki smo ga poimenovali »oralni spolni kontakt«. To vedenje je bilo prisotno pred, med in tudi po parjenju ne glede na starostni oz. spolni status samice. Njegova funkcija je še neznana. Pri vseh parjenjih je prišlo do poškodb pedipalpov v genitalnih odprtinah samic. Parjeni samci svojih pedipalpov niso mogli več ponovno uporabiti, medtem ko so se parjene samice lahko ponovno parile. Iz tega sklepamo, da je C. darwini poliandrična vrsta. Samci so si kasneje po paritvi sami odgriznili poškodovane pedipalpe in postali popolni evnuhi. Samice so bile po parjenju pogosto agresivne do samcev, občasno je prišlo do spolnega kanibalizma. Primerjava odraslih in teneralnih samic je pokazala, da so se starejše samice na dvorjenje samcev večinoma odzvale z agresijo, parjenja so bila krajša in so se pogosteje zaključila s spolnim kanibalizmom kot parjenja s teneralnimi samicami. The spider species Caerostris darwini is known for utilizing the largest orb webs, built from the biomaterial which by tensile strenght exceeds all other known silk spiders and even most of the sythetic fibers. Recent publications for this species also report sexual size dimorphism, which is linked with unusual sexual behaviors. However, sexual behavior in this species is virtually unexplored. Therefore, we conducted field research in Madagascar and controlled experiments in the laboratory. Our study reveals that C. darwini exhibits sexual strategies that are similar to those in other sexually size-dimorphic species. These include male preference for freshly molted (i.e. teneral) females, male palp breakage within female genitals during copulation and sexual cannibalism. Male courtship is intense and includs mate binding. During courtship, we also observed a previously unknown spider behavior that we term “oral sexual contact”. Males salivated onto female genitalia pre-, during, and post-copulation, irrespective of female’s age or mating status. The adaptive significance of “sexual oral contact” remains elusive. All insertions resulted in male palp damage. The males self-emasculated their damaged palps to become eunuchs. Females were often aggressive towards males after mating and sometimes cannibalized them. While males could not reuse their damaged palps, previously mated females were able to reuse their plugged genitals, implying a polyandrous mating system in C. darwini. Comparing adult and teneral females showed that adult females typically respond aggressively to male courtship, have shorter copulations and higher occurrences of sexual cannibalism.