Zoophytophagous insects can substitute animals for plant resources when prey is scarce. Many arthropods feed on conspecifics to survive in these conditions. An individual's tendency for cannibalism may depend on its genotype along with its diet specialization, in interaction with the availability of alternative food resources. We compared two isogroup lines of the zoophytophagous mullein bug, e...

The effect of imidacloprid on fecundity in twospotted spider mites, Tetranychus urticae Koch, was investigated in laboratory experiments using individual females on bean leaf discs. Mites were directly exposed to spray formulations of imidacloprid or fed on discs cut from a systemically treated bean plant. Imidacloprid-treated T. urticae produced 10-26% more eggs during the first 12 d of adult ...

The impact of rare but positive events on the design of organisms has been largely ignored, probably due to the paucity of recordings of such events and to the difficulty of estimating their impact on lifetime reproductive success. In this respect, we investigated the size of spider webs in relation to rare but large prey catches. First, we collected field data on a short time-scale using the c...

Recent studies have delineated a large Nearctic Müllerian mimicry complex in Dasymutilla velvet ants. Psorthaspis spider wasps live in areas where this mimicry complex is found and are phenotypically similar to Dasymutilla. We tested the idea that Psorthaspis spider wasps are participating in the Dasymutilla mimicry complex and that they codiverged with Dasymutilla. We performed morphometric an...

An annotated checklist of ptyctimous mite taxa from Southern Vietnam, including 18 species, 11 genera and seven families, is provided. Three new species.-Apoplophora minuscula Niedbała sp. nov., Acrotritia proxima Niedbała sp. nov. and Sabahtritia dongnaiensis Niedbała sp. nov.-are described. Some remarks on descriptions of Vietnamese Apoplophora pantotrema (Berlese, 1913) and Arphthiracarus tu...

Altogether 24 species of ptyctimous mites were found in sifting litter samples from the Cameroon. Twelve new species of the ptyctimous mites, Indotritia montkoupensis sp. nov., Acrotritia furca sp. nov., Acrotritia quasidivida sp. nov., Hoplophthiracarus kumboensis sp. nov., Hoplophthiracarus reticulatus sp. nov., Hoplophthiracarus spinus sp. nov., Steganacarus (Rhacaplacarus) quaternarius sp. ...

Theory predicts that local mate competition (LMC) favors the evolution of female-biased sex ratios. Empirical support of this prediction is indirect and comes from comparative studies or from studies showing that individuals can adjust their offspring sex ratio in response to varying LMC intensities. Replicate lines from a population of the spider mite Tetranychus urticae were selected under th...

Sex-ratio adjustments are commonly observed in haplodiploid species. However, the underlying proximate mechanisms remain elusive. We investigated these mechanisms in Tetranychus urticae, a haplodiploid spider mite known to adjust sex ratio in response to the level of local mate competition (LMC). In this species, egg size determines fertilization probability, with larger eggs being more likely ...

BACKGROUND In group-living animals, social interactions and their effects on other life activities such as foraging are commonly determined by discrimination among group members. Accordingly, many group-living species evolved sophisticated social recognition abilities such as the ability to recognize familiar individuals, i.e. individuals encountered before. Social familiarity may affect within...