In surveys of apple-production areas east of the Cascade Mountains of Washington, broadleaf plantain, Plantago major Linnaeus (Plantaginaceae) was common throughout while narrowleaf plantain, P. lanceolata Linnaeus, was most common south of Orondo, Douglas County (47.7u latitude). Rosy apple aphid was the most common aphid on these two herbaceous plants; however, colonies were scarce, on only 1...

Ethological aspects and chemical communication at close-range between the sexes of Lysiphlebus testaceipes Cresson (Hymenoptera: Braconidae) have been investigated through behavioral bioassays and chemical analysis. The attractiveness toward males of whole-body extracts of females and males in hexane and acetone was evaluated, adopting male fanning behavior as a key behavioral component. Also, ...

Aphidiinae (Braconidae: Aphidiinae) is a subfamily of endoparasitic wasps specialized in parasitizing aphids. Although, to date, different methods have been used to measure parasitism level, obtaining an accurate estimate remains challenging due to several limiting factors. This study was set to: 1) Compare efficiency of conventional and molecular-based methods in estimating parasitism level of...

The evolutionary maintenance of sex is one of the big unresolved puzzles in biology. All else being equal, all-female asexual populations should enjoy a two-fold reproductive advantage over sexual relatives consisting of male and female individuals. However, the "all else being equal" assumption rarely holds in real organisms because asexuality tends to be confounded with altered genomic consti...

Interactions of the parasitoid Lysiphlebus testaceipes (Cresson) and the greenbug, Schizaphis graminum (Rondani), on greenbug-resistant 'Cargill 607E' (antibiosis), 'Cargill 797' (primarily tolerance), and -susceptible 'Golden Harvest 510B' sorghum, Sorghum bicolor (L.) Moench, were tested using three levels of biotype I greenbug infestation. The parasitoid infestation rate was 0.5 female and 1...

Naturally occurring parasitoids may provide sufficient control of aphid pests in fields undisturbed by insecticides. Yet the efficacy of these parasitoids may be strongly influenced by characteristics of their hosts and by the availability of alternative hosts in neighbouring crops. In the present study, parasitoid guild structure was compared in two aphid species, Brevicoryne brassicae and Lip...