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.

Transgenic Bt maize and Rhopalosiphum padi (Hom., Aphididae) performance

Abstract: 1. The population abundance and age structure of Rhopalosiphum padi, one of the most common maize aphid species, on transgenic Bt (expressing the CrylAb protein) and non-Bt isogenic maize was studied in commercial plots during three crop seasons. 2. A higher density of aphids, particularly alates and young nymphs, occurred in Bt plots at very young maize development stages, corresponding to the settlement period, in the 3 years studied. Possible causes are discussed. After this period, there were no differences between Bt and non-Bt maize. 3. Mortality, development, and reproduction of the offspring of alate forms of R. padi and the offspring of different generations of apterous forms fed with Bt maize were evaluated in the laboratory under controlled conditions. 4. The developmental and pre-reproductive times of the offspring of the first generation of alatae were shorter and the intrinsic rate of natural increase (r m ) higher when aphids fed on Bt maize. The opposite occurs with the offspring of the first generation of apterous mothers, which have lower nymphal and adult mortality, shorter developmental and pre-reproductive times, a higher effective fecundity rate, and greater r m , when fed on non-Bt maize. The differences in aphid development on the two cultivars may be linked to changes in host-plant quality due to pleiotropic effects of the genetic modification. 5. No differences on aphid mortality, developmental and pre-reproductive times, fecundity, and r m were found between the offspring of apterous aphids maintained on Bt or non-Bt maize for several generations.

The Multicoloured Asian Ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae), a threat for native aphid predators in Belgium?

Abstract: The Multicoloured Asian Ladybird (Harmonia axyridis Pallas 1773) is native to large parts of Asia. It preys mostly on tree-dwelling hemipteran insects such as psyllids, scale insects and aphids (1). It is a commercially attractive biocontrol agent for aphid populations because its larvae are very voracious, polyphagous and easy to rear (2-4). H. axyridis is widely used for reducing pest aphid populations in greenhouses, orchards and gardens in North America since 1916 and in Western Europe since 1982, where it is sold by different private companies (e.g. Biotop SAS, BioBest and Koppert) (1,4). Little attention has been paid to the development of feral populations of H. axyridis in Europe. This is surprising given the rapid colonisation of a wide range of American ecosystems, and growing concerns over the negative impact of natural enemy introductions (57). Recent observations suggest that this species is now invading (semi-)natural ecosystems in Belgium and may become a potential threat for native ladybird species and other aphid predators.

Impact of predation on establishment of the soybean aphid, Aphis glycines in soybean, Glycine max

Abstract: The soybean aphid, Aphis glycines Matsumura is a new invasive pest of soybean in North America. We studied the ability of the existing predator community in soybean to reduce A. glycines establishment in field studies using either predator exclusion, open, or leaky cages that allowed aphid emigration but limited predation. Cages were infested with uniform initial densities of A. glycines adults and subsequent populations of aphids and predators were monitored over 24 h. The most abundant predators in these trials included the carabid beetles Elaphropus anceps (Le Conte), Clavina impressefrons Le Conte, Bembidion quadrimaculatum Say and spiders (Salticidae and Lycosidae). Foliar predators were less abundant and included; Harmonia axyridis Pallas, Coccinella septempunctata (L.), and Orius insidious (Say). Over the 2-year study, we found statistically significant predation on adult A. glycines in one out of six trials at 15 h and two out of six trials at 24 h. There was never significant evidence for predation of nymphs in any trial, however overall survival (adults + nymphs) was significantly reduced in one out of six trials at 15 h and three out of six trials at 24 h. Based on these results we suggest that generalist predators can be a significant but variable factor influencing the establishment of A. glycines populations in soybean. The impact of existing predator communities should be further investigated as a means of managing A. glycines populations in North American soybean production systems.

Role of terpenes from aphid-infested potato on searching and oviposition behavior of Episyrphus balteatus

Abstract: To cope with pathogen and insect attacks, plants develop different mechanisms of defence, in both direct (physical and chemical) and indirect ways (attractive volatiles to entomophagous beneficials). Plants are then able to express traits that facilitate "top-down" control of pests by attracting herbivore predators. Here we investigate the indirect defence mechanism of potato plants by analyzing the volatile patterns of both healthy and aphid- infested plants. Important changes in the emitted terpene pattern by the Myzus persicae infested host plant were observed. Using Solid Phase MicroExtraction (SPME) and GC-MS, the (E)-β-farnesene (EBF) appeared to be emitted by aphid-infested potato and not by healthy plants. To assess the infochemical role of these volatile releases after aphid damage on the aphidophagous predators Episyrphus balteatus, the hoverfly foraging behavior was assessed using the Observer 5.0 software (Noldus, Wageningen, The Netherlands). Aphid- free potato plants were also used as a control volatile source in the predator behavioral study. While aphid-infested plants induced efficient searching and acceptation behaviors leading to egg-laying, no kairomonal effect of healthy potato plants was observed, leading to longer immobility durations and shorter searching periods in the net cage. High oviposition rate of E. balteatus was observed when aphid-infested potato was used (mean of 48.9 eggs per laying and per female). On the other hand, no egg was produced by the hoverfly on healthy aphid-free plants. The E. balteatus foraging and reproductive behaviors according to the volatile emission from aphid-infested plants are discussed in relation to the potential use of active infochemical molecules in integrated aphid pest management.

Effects of fertilizer, fungal endophytes and plant cultivar on the performance of insect herbivores and their natural enemies

Abstract: Summary 1Endophytic fungi are associates of most species of plants and may modify insect community structures through the production of toxic alkaloids. Fertilization is known to increase food plant quality for herbivores, but it is also conceivable that additional nitrogen could increase the production of the insect toxic alkaloid, peramine, in endophyte-infected plants. 2The relative importance of soil fertility and endophyte infection on herbivores and their natural enemies is unknown. As performance of the host plant is often affected by an interaction between endophyte infection and genetic background, four different plant cultivars were tested. The main questions addressed in this study were whether plant cultivar and fertilizer addition to endophyte-infected and endophyte-free Lolium perenne affect alkaloid concentrations, plant life-history traits and the abundances of aphid species and their parasitoids. 3In a full factorial outdoor experiment we found a strong positive effect of fertilizer on plant biomass and on the abundance of aphids and parasitoids. While plant traits differed between cultivars, there was little effect of cultivar on either aphid or parasitoid abundance. Only endophyte-infected plants contained alkaloids, and the concentration of peramine was enhanced in fertilized plants. However, endophyte infection had no negative effect on aphid or parasitoid abundances. Plant traits were only weakly influenced by endophyte infection in the field, which contrasts with plant growth room studies, where both germination rate and plant height were influenced by endophyte–cultivar interactions. 4The generally weak effects of endophytes in the outdoor experiment could be explained by various additional constraints under field conditions and the relatively low peramine concentration that we observed.