Gender-specific differences in cannibalism between a laboratory strain and a field strain of a predatory mite

Many phytoseiid species, including Phytoseiulus persimilis, are known to engage in cannibalism when food is scarce and when there is no possibility to disperse. In nature adult females of P. persimilis are known to disperse when prey is locally depleted. Males, in contrast, are expected to stay and wait for potential mates to mature. During this phase, males can obtain food by cannibalizing. Therefore, we hypothesize that male P. persimilis exhibit a higher tendency to cannibalize than females. Because rearing conditions in the laboratory usually prevent dispersal, prolonged culturing may also affect cannibalistic behavior. We hypothesize that this should especially affect cannibalism by females, because they consume far more food. We tested these hypotheses by comparing males and females from two strains, one of which had been in culture for over 20 years, whereas the other was recently collected from the field. It is known that this predator can discriminate between kin and non-kin and prefers cannibalizing the latter, hence to construct lines with high relatedness we created isofemale lines of these two original strains. We subsequently tested to what extent the adult females and males of the original strains and the isofemale lines cannibalized conspecific larvae from the same strain/line in a closed system. Relatedness with the victims did not affect cannibalistic behavior, but males engaged more often in cannibalism than females, and females of the laboratory strain engaged more in cannibalism than those of the field strain, both in agreement with our ideas. We hypothesize that the difference in cannibalism between the two genders will increase when they have the alternative to disperse

Components of the sex pheromone of the currant pug moth, Eupithecia assimilata, a re-emergent hop pest in UK

After an absence of 50 years, the currant pug moth, Eupithecia assimilata Doubleday (Lepidoptera: Geometridae), has reappeared as an important pest of hops, Humulus lupulus L. (Cannabaceae), in the UK. Pheromone gland extracts from virgin female E. assimilata moths were shown to contain (3Z,6Z)-cis-9,10-epoxyheneicosadiene (3Z,6Z-cis-9,10-epoxy-21:H) by gas chromatography linked to mass spectrometry. (3Z,6Z,9Z)-heneicosatriene (3Z,6Z,9Z-21:H) was also found as a minor component in one of two extracts. In field experiments, significant numbers of male E. assimilata moths were caught in traps baited with the (9S,10R)-enantiomer of 3Z,6Z-cis-9,10-epoxy-21:H but not in those baited with the (9R,10S)-enantiomer or racemic mixture. Addition of 3Z,6Z,9Z-21:H at the ratio present in gland extracts greatly reduced the attractiveness of the epoxydiene