Aphid

About: Aphid is a research topic. Over the lifetime, 11380 publications have been published within this topic receiving 229721 citations. The topic is also known as: Aphidoidea & plant lice.

The effect of the quality and size of host aphid species on the biological characteristics of Aphidius colemani (Hymenoptera: Braconidae: Aphidiinae)

Abstract: A suitable host provides, at least, the minimum nutritional and physiological conditions for the development of the imma- ture stages of a parasitoid. Host quality may influence the developmental time, mortality rate, longevity and fecundity of parasitoids. This work evaluates the suitability and quality of Aphis gossypii Glover, Brevicoryne brassicae (Linne), Myzus persicae (Sulzer), Rhopalosiphum maidis (Fitch) and Schizaphis graminum (Rondani) as hosts for Aphidius colemani Viereck. Twenty second-instar nymphs of each aphid species were exposed to parasitism for one hour, and then kept in a climatic chamber at 22 ± 1°C, 70 ± 10% RH and a 12 h photophase. The aphid B. brassicae was unsuitable for the development of A. colemani. The different aphid host spe- cies varied in size: M. persicae > (R. maidis = S. graminum) > A. gossypii. Parasitoid fitness decreased accordingly when reared on (M. persicae = R. maidis) > S. graminum > A. gossypii. Large hosts seem to be better than small hosts based on parasitoid size. Egg load of A. colemani was related probably more on the ability of the parasitoid larva to obtain nutritional resources from the different host species than on host size.

Characterization of a facultative endosymbiotic bacterium of the pea aphid Acyrthosiphon pisum.

Abstract: The pea aphid U-type symbiont (PAUS) was investigated to characterize its microbiological properties. Fluorescence in situ hybridization (FISH) and electron microscopy revealed that PAUS was a rod-shaped bacterium found in three different locations in the body of the pea aphid Acyrthosiphon pisum: sheath cells, secondary mycetocytes, and hemolymph. Artificial transfer experiments revealed that PAUS could establish stable infection and vertical transmission when introduced into uninfected pea aphids. When 28 aphid species collected in Japan were subjected to a diagnostic PCR assay, four species of the subfamily Aphidinae (Aphis citricola, Aphis nerii, Macrosiphum avenae, and Uroleucon giganteus) and a species of the subfamily Pemphiginae (Colopha kansugei) were identified to be PAUS-positive. The sporadic incidences of PAUS infection without reflecting the aphid phylogeny can be best explained by occasional horizontal transfers of the symbiont across aphid lineages.

Effect of late season insect infestation on yield, yield components and oil quality of Brassica napus, B. rapa, B. juncea and Sinapis alba in the Pacific Northwest region of the United States.

Abstract: The effect of late season insect infestation on seed yield, yield components, oil content and oil quality of two canola species (Brassica napus L. and B. rapa L.) and two mustard species (B. juncea L. and Sinapis alba L.) was examined over 2 years. In each year, ten genotypes from each species were evaluated with late season insects controlled with either methyl parathion or endosulfan insecticides, and without insecticides. Major late season insect damage in 1992 was caused by cabbage seedpod weevil (Ceutorhynchus assimilis Paykull), while diamondback moth (Plutella xylostella L.) and aphids (primarily cabbage aphids, Brevicoryne brassicae L.) were major insect pests in 1993. Insecticide application was very effective in controlling diamondback moth larvae and adult cabbage seedpod weevils, but only partially effective in controlling aphids. Higher numbers of diamondback moth larvae were observed on mustard species compared to canola species. S. alba was completely resistant to cabbage seedpod weevil and there was no damage due to this pest observed. Aphid colonization was observed on plants from all species, but infestation on S. alba and B. rapa occurred too late to have a major effect on seed yield. Seed oil content of canola species was significantly reduced by insect damage although oil quality (indicated by fatty acid profile) was not affected by insect attack. Uncontrolled insect infestation reduced seed yield of canola species by 37 and 32 % in B. napus and B. rapa, respectively. Least yield reduction occurred in S. alba, where average yield reduction from plants in untreated control plots was < 10 % of insecticide treated plants. S. alba, therefore, has good potential as an alternative crop suitable for northern Idaho because it can be grown with reduced late season insecticide application.

Detached leaf and whole plant assays for soybean aphid resistance: differential responses among resistance sources and biotypes.

Abstract: The soybean aphid, Aphis glycines Matsumura, is a pest of cultivated soybean, Glycine max (L.) Merr., in North America. Recent developments in host plant resistance studies have identified at least four soybean aphid resistance genes (Rag1-4) and two soybean aphid biotypes (biotype 1 and 2), defined by differential survivability on resistant soybean. Detached soybean leaves were tested as a more rapid and practical assay to assess host plant resistance and virulence. Two susceptible lines ('Wyandot' and 'Williams 82') and two resistant lines (PI 243540 and PI 567301B) were examined. Various life history characteristics were compared among aphids on whole plants and detached leaves. Results indicated that resistance to soybean aphid was lost using detached leaves of PI 567301B but retained with PI 243540. To test for aphid virulence, net fecundities were compared among biotype 1 and biotype 2 after rearing on detached leaves of the resistant 'Jackson' (to which biotype 2 is virulent). A significant difference was detected in net fecundities among biotypes on detached leaves of Jackson and used to predict growth rates and virulence from 30 field-collected individuals of unknown virulence. No field individuals matched biotype 2 predictions, but four individuals had higher net fecundities than biotype 2 predictions (13%) and could be considered moderately virulent. The results indicated that the retention of soybean aphid resistance in detached leaves is dependent on PI and resistant source, but if resistance is retained, detached leaves could be used to determine soybean aphid virulence.