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Uroleucon
About: Uroleucon is a research topic. Over the lifetime, 150 publications have been published within this topic receiving 2266 citations.
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TL;DR: Phylogenetic trees based on trpE (plasmid gene) and trpB (chromosomal genes) from eight species of aphids are congruent, indicating a lack of exchange of plasmids among endosymbionts from different aphid species.
Abstract: The aphid Uroleucon sonchi contains a prokaryotic endosymbiont (Buchnera) with plasmids having trpEG as well as remnants of trpE pseudogenes. In this respect it resembles Buchnera from the aphid Diuraphis noxia. Phylogenetic trees based on trpE (plasmid gene) and trpB (chromosomal genes) from eight species of aphids are congruent, indicating a lack of exchange of plasmids among endosymbionts from different aphid species.
38 citations
TL;DR: Obs observations of natural aphid colonies revealed that a collective twitching and kicking response (CTKR) was frequently evoked during oviposition attempts of the parasitoid wasp Aphidius colemani and during attacks of aphidophagous larvae, suggesting that visual signals in combination with twitching-related substrate vibrations may play an important role in synchronising defense among members of a colony.
Abstract: The prevalent way aphids accomplish colony defense against natural enemies is a mutualistic relationship with ants or the occurrence of a specialised soldier caste typcial for eusocial aphids, or even both. Despite a group-living life style of those aphid species lacking these defense lines, communal defense against natural predators has not yet been observed there. Individuals of Aphis nerii (Oleander aphid) and Uroleucon hypochoeridis, an aphid species feeding on Hypochoeris radicata (hairy cat's ear), show a behavioral response to visual stimulation in the form of spinning or twitching, which is often accompanied by coordinated kicks executed with hind legs. Interestingly, this behaviour is highly synchronized among members of a colony and repetitive visual stimulation caused strong habituation. Observations of natural aphid colonies revealed that a collective twitching and kicking response (CTKR) was frequently evoked during oviposition attempts of the parasitoid wasp Aphidius colemani and during attacks of aphidophagous larvae. CTKR effectively interrupted oviposition attempts of this parasitoid wasp and even repelled this parasitoid from colonies after evoking consecutive CTKRs. In contrast, solitary feeding A. nerii individuals were not able to successfully repel this parasitoid wasp. In addition, CTKR was also evoked through gentle substrate vibrations. Laser vibrometry of the substrate revealed twitching-associated vibrations that form a train of sharp acceleration peaks in the course of a CTKR. This suggests that visual signals in combination with twitching-related substrate vibrations may play an important role in synchronising defense among members of a colony. In both aphid species collective defense in encounters with different natural enemies was executed in a stereotypical way and was similar to CTKR evoked through visual stimulation. This cooperative defense behavior provides an example of a surprising sociality that can be found in some aphid species that are not expected to be social at all.
37 citations
TL;DR: In experiments using potted host plants, the specialist was better able than the generalist to escape predation by walking to nearby hosts, and this strategy of persistence depends on specificity to a long-lived, clumped, bushy host such as S. nemoralis.
Abstract: Benefits of host specificity for Uroleucon nigrotibium (Homoptera: Aphididae) include not only improved physiological efficiency but also enhanced success of dispersal and defense tactics. I tested the physiological efficiency hypothesis, which predicts a higher reproductive rate for this specialist than for the generalist U. gravicorne when each is reared on their shared host, Solidago nemoralis. Between-species comparisons of developmental times and fecundities of individuals reared on naturally occurring and potted screenhouse host plants supported this prediction for the spring but not in summer, when most reproduction occurs. Greater physiological efficiency of the specialist is also supported by its greater size, which may aid in dispersing and in escaping enemies by walking. Field colonies of the specialist were found to produce few winged forms and to disperse frequently via apterae walking between hosts; consequently, U. nigrotibium infestations are larger and longer lived and are attacked more by enemies than those of its generalist congener. In experiments using potted host plants, the specialist was better able than the generalist to escape predation by walking to nearby hosts. This strategy of persistence depends on specificity to a long-lived, clumped, bushy host such as S. nemoralis.
36 citations
TL;DR: Nonsynonymous rates for trpEG are accelerated within Buchnera of Uroleucon, indicating a change in selection intensity within this genus, and Synonymous substitutions are about twice as high for plasmid-borne genes as for chromosomal genes in the same lineages, suggesting higher mutation rates for genes on plasmids.
33 citations
TL;DR: The aphidiines presented in this work were identified from 97 aphid taxons occurring on 236 plant taxons and phylogenetic relationships inside the “dorsale-yomenae” species group and related species were reconstructed using cladistic distance methods.
Abstract: A review of aphidiine wasps (Hymenoptera: Braconidae) parasitizing the Uroleucon species in the West Palaearctic is presented. Eleven species are keyed and illustrated. In addition, a new hymenopteran parasitoid species: Praon nonveilleri n. sp. from Uroleucon inulicola (Hille Ris Lambers) infesting Inula ensifolia L., is described. The new species is diagnosed and illustrated. It belongs to the “dorsale-yomenae” species group and was collected from the Djetinja canyon in Serbia and Montenegro. The aphidiines presented in this work were identified from 97 aphid taxons occurring on 236 plant taxons. Furthermore, 361 original parasitoid – host aphid – host plant associations of the species mentioned in the key are presented. Finally, phylogenetic relationships inside the “dorsale-yomenae” species group and related species were reconstructed using cladistic distance methods.
29 citations