Brevicoryne Brassicae (brevicoryne + brassicae)

Distribution by Scientific Domains

Selected Abstracts

Maternal host plant effects on aphid performance: contrasts between a generalist and a specialist species on Brussels sprout cultivars

Muhammad Tariq
1The performance of the second generation (G2) of alates and apterae of a generalist, Myzus persicae, and a specialist, Brevicoryne brassicae, aphid species reared on Chinese cabbage or cabbage was evaluated on five cultivars of Brussels sprout. 2Aphid performance was influenced both by the type of host on which the parent aphid had been reared and by the host on which it was feeding when reproducing. 3The fecundity of the G2 of alates of both aphid species reared on Chinese cabbage differed significantly between all the cultivars of Brussels sprout and, on average, was 25% higher than those reared on cabbage. These differences were also apparent for the intrinsic rate of increase of B. brassicae but not for M. persicae. 4There was a trend for the G2 of alates from Chinese cabbage to have greater fecundity compared with aphids from cabbage. These differences were significant for the fecundity of the G2 of alates of both aphid species on Brussels sprout cultivars Fillbasket (30% higher), Red Delicious (35% higher) and Winter Harvest (25% higher) than those reared on cabbage. 5The intrinsic rate of increase for the G2 of alates of B. brassicae from Chinese cabbage was significantly different on all Brussels sprout cultivars tested. The intrinsic rate of increase differed significantly between aphids reared on either Chinese cabbage or cabbage on cultivars Oliver and Darkmar-21 (M. persicae) and Red Delicious and Winter Harvest (B. brassicae). The cv. Oliver appeared to be the most consistently good host; Red Delicious was the poorest host overall. [source]

The role of pre- and post- alighting detection mechanisms in the responses to patch size by specialist herbivores

OIKOS, Issue 3 2005
Tibor Bukovinszky
Experimental data on the relationship between plant patch size and population density of herbivores within fields often deviates from predictions of the theory of island biogeography and the resource concentration hypothesis. Here we argue that basic features of foraging behaviour can explain different responses of specialist herbivores to habitat heterogeneity. In a combination of field and simulation studies, we applied basic knowledge on the foraging strategies of three specialist herbivores: the cabbage aphid (Brevicoryne brassicae), the cabbage butterfly (Pieris rapae L.) and the diamondback moth (Plutella xylostella L.), to explain differences in their responses to small scale fragmentation of their habitat. In our field study, populations of the three species responded to different sizes of host plant patches (9 plants and 100 plants) in different ways. Densities of winged cabbage aphids were independent of patch size. Egg-densities of the cabbage butterfly were higher in small than in large patches. Densities of diamondback moth adults were higher in large patches than in small patches. When patches in a background of barley were compared with those in grass, densities of the cabbage aphid and the diamondback moth were reduced, but not cabbage butterfly densities. To explore the role of foraging behaviour of herbivores on their response to patch size, a spatially explicit individual-based simulation framework was used. The sensory abilities of the insects to detect and respond to contact, olfactory or visual cues were varied. Species with a post-alighting host recognition behaviour (cabbage aphid) could only use contact cues from host plants encountered after landing. In contrast, species capable with a pre-alighting recognition behaviour, based on visual (cabbage butterfly) or olfactory (diamondback moth) cues, were able to recognise a preferred host plant whilst in flight. These three searching modalities were studied by varying the in flight detection abilities, the displacement speed and the arrestment response to host plants by individuals. Simulated patch size , density relationships were similar to those observed in the field. The importance of pre- and post- alighting detection in the responses of herbivores to spatial heterogeneity of the habitat is discussed. [source]

Arabidopsis myrosinases TGG1 and TGG2 have redundant function in glucosinolate breakdown and insect defense

Carina Barth
Summary In Arabidopsis and other Brassicaceae, the enzyme myrosinase (, -thioglucoside glucohydrolase, TGG) degrades glucosinolates to produce toxins that deter herbivory. A broadly applicable selection for meiotic recombination between tightly linked T-DNA insertions was developed to generate Arabidopsis tgg1tgg2 double mutants and study myrosinase function. Glucosinolate breakdown in crushed leaves of tgg1 or tgg2 single mutants was comparable to that of wild-type, indicating redundant enzyme function. In contrast, leaf extracts of tgg1tgg2 double mutants had undetectable myrosinase activity in vitro, and damage-induced breakdown of endogenous glucosinolates was apparently absent for aliphatic and greatly slowed for indole glucosinolates. Maturing leaves of myrosinase mutants had significantly increased glucosinolate levels. However, developmental decreases in glucosinolate content during senescence and germination were unaffected, showing that these processes occur independently of TGG1 and TGG2. Insect herbivores with different host plant preferences and feeding styles varied in their responses to myrosinase mutations. Weight gain of two Lepidoptera, the generalist Trichoplusia ni and the facultative Solanaceae-specialist Manduca sexta, was significantly increased on tgg1tgg2 double mutants. Two crucifer-specialist Lepidoptera had differing responses. Whereas Plutella xylostella was unaffected by myrosinase mutations, Pieris rapae performed better on wild-type, perhaps due to reduced feeding stimulants in tgg1tgg2 mutants. Reproduction of two Homoptera, Myzus persicae and Brevicoryne brassicae, was unaffected by myrosinase mutations. [source]

The influence of genetic background on resistance to the cabbage aphid (Brevicoryne brassicae) in Kale (Brassica oleracea var. acephala)

Summary Resistance to Brevicoryne brassicae has been identified in the progeny of two selected kale (B. oleracea var. acephala) plants, one from the F1 hybrid cultivar ,Arsis RS' and one from the landrace ,Butzo'. These plants were crossed with susceptible B. oleracea morphotypes that have different periods to flowering. The type of susceptible plant line used had an effect on the resistance phenotypc of the progeny. Tested F2 populations derived from these crosses show that resistance is not under simple genetic control. This, in addition to variation in aphid numbers within accessions, suggests that separation of genetic components of control from environmental ,noise' for any accession may only be possible by the production of double haploid plant lines. [source]