The cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae), is a perennial pest that specializes on plants of the Brassicaceae family, attacking winter canola (Brassica napus L.) mainly during and after flowering. Under field conditions, cabbage aphid colonizes the upper flowering canopy. Population dynamics of aphids in the flowering canopy could be regulated by differences in either p...

To study the effects of wheat-maize intercropping on the population dynamics of wheat aphids and their natural enemies, wheat-maize intercropping patterns were divided into four levels: 8:2, 6:2, and 4:2 intercropping, and monoculture wheat. The results showed that as the wheat coverage rate decreased, the quantities of immigrating winged aphids and their natural enemies significantly differed;...

Alfalfa (Medicago sativa L.) persistence and forage and cow-calf production were evaluated on pastures containing smooth bromegrass with or without grazing-tolerant or hay-type alfalfa cultivars rotationally stocked in either a season-long or complementary system. In 1997, six 2.02-ha pastures were seeded with smooth bromegrass, a mixture of a grazing-tolerant alfalfa (Amerigraze variety) and s...

BACKGROUND RNA interference (RNAi) is an effective tool to examine the function of individual genes. Carboxylesterases (CarE, EC 3.1.1.1) are known to play significant roles in the metabolism of xenobiotic compounds in many insect species. Previous studies in our laboratory found that CarE expression was up-regulated in Aphis gossypii (Glover) (Hemiptera: Aphididae) adults of both omethoate and...

Pea aphid (Acyrthosiphon pisum) clones have been shown to be adapted to particular host plant species but it is unknown whether there are host races. A 1101 base pair region of the mitochondrial cytochrome oxidase I gene (COI) was sequenced for 21 pea aphid clones that had been collected from different host plants in Canada and the U.S.A. Only five closely related mitochondrial haplotypes were ...

The natural occurrence of entomophthoralean fungi pathogenic towards aphids on cereal and potato crops was investigated in the years 2009, 2010, and 2011. Infected aphids were sampled in three bioclimatic zones in Tunisia (Beja, Cap bon, and Kairouan) and fungal species were determined based on morphological characters such as shape, size, and number of nuclei in the primary conidia. Polymerase...

The benzoylphenyl urea insect growth regulators (IGRs), diflubenzuron, alsyston, CGA 112913, UC 62644 and Thuringiensin, were tested on adult and late third instar Trioxys pallidus and first instar walnut aphids. The organophosphates, phosalone and azinphosmethyl were used as positive controls. The IGRs and Thuringiensin were not acutely toxic to adult and larval Trioxys when contact, topical a...

Aphids harbour both an obligate bacterial symbiont, Buchnera aphidicola, and a wide range of facultative ones. Facultative symbionts can modify morphological, developmental and physiological host traits that favour their spread within aphid populations. We experimentally investigated the idea that symbionts may also modify aphid behavioural traits to enhance their transmission. Aphids exhibit m...

Artificial aphid diets have been previously developed for the pea aphid, Acyrthosiphon pisum (Harris), and the green peach aphid, Myzus persicae (Sulzer). The ability to rear aphids on an artificial diet allows for selectively adding or subtracting compounds from an aphid's food source to determine the effect on fecundity and longevity. Five diets previously developed for the green peach aphid ...

Most aphids possess intracellular bacteria of the genus Buchnera. The bacteria are transmitted vertically via the aphid ovary, and the association is obligate for both partners: Bacteria-free aphids grow poorly and produce few or no offspring, and Buchnera are both unknown apart from aphids and apparently unculturable. The symbiosis has a nutritional basis. Specifically, bacterial provisioning ...