Traumatic mating causes strict monandry in a wolf spider

DEAR EDITOR,We identified strict monandry in a wandering wolf spider species(Pardosa pseudoannulata) and revealed the underlying mechanisms of this mating structure. Evidence indicated that males damaged the inner walls of the female genital tract with the sharp part of their intromittent organ during insemination. The traumatic mating caused hemolymph hemorrhage, which mixed with seminal fluid and gradually formed an impermeable amorphous mating plug after about15 days, completely blocking the female copulatory opening.

Pure SnO₂Gas Sensor with High Sensitivity and Selectivity towards C₂H₅OH

To observation, poisonous gases in the environment, Sensors with high selectivity, high response and low operating temperature are required. In this work, pure SnO2 nanoparticles was prepared by using a simple and inexpensive technique (hydrothermal method) without a template. Various confirmatory tests were performed to characterize SnO2 nanoparticles such as energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transition Electron Microscopy (TEM), during the detection of the gas, we found that pure SnO2 nanoparticles has a high selectivity for ethanol to 100 ppm at a low temperature (180°C) and a high response (about 27 s) and a low detection limit of 5 ppm, also it have response/recovery times about (4 s, 2 s) respectively. The distinctive sensing properties of SnO2 sensor make it a promising candidate for ethanol detection. Furthermore, the gas-sensing mechanism have been examined.

Conspicuous cruciform silk decorations deflect avian predator attacks

Although camouflage as an effective antipredator defense strategy is widespread across animals,highly conspicuous color patterning is not uncommon either.Many orb-web spiders adorn their webs with extra bright white silk.These conspicuous decorations are hypothesized to deter predators by warning the presence of sticky webs,camouflaging spiders,acting as a decoy,or intimidating predators by their apparent size.The decorations may also deflect predator attacks from spiders.However,empirical evidence for this deflection function remains limited.Here,we tested this hypothesis using the X-shaped silk cruciform decorations built by females of Argiope minuta.We employed visual modeling to quantify the conspicuousness of spiders and decorations from a perspective of avian predators.Then,we determined actual predation risk on spiders using naïve chicks as predators.Spider bodies and decorations were conspicuous against natural backgrounds to the avian visual systems.Chicks attacked the spider main bodies significantly less frequently on the decorated webs than on the undecorated webs,thus reducing predation risk.When both spiders and decorations were present,chicks also attacked the spider main bodies and their legs or decorations,and not randomly:they attacked the legs or decorations sooner and more frequently than they attacked the main bodies,independent of the ratio of the surface area between the decoration and spider size.Despite the increase in detectability,incorporating a conspicuous cruciform decoration to the web effectively defends the spider by diverting the attack toward the decoration or leg,but not by camouflaging or intimidating,thus,supporting the deflection hypothesis.