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"Host selection"
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Olympic Games and global cities : what future for an Olympic system in turmoil?
This volume offers a comprehensive overview of current debates on the influence of the Olympic Games on cities, urban policies and the governance of global cities, making a valuable contribution to the fields of Olympic studies and urban studies. Historically, Western cities such as Paris, London, and later Los Angeles, have been the primary hosts of the summer Games. However, the link that existed between the world metropolises of the last century and the Games has deeply changed. Growing concerns about the Games' costs and environmental impact have prompted a shift in the expectations of candidate cities and the International Olympic Committee (IOC). This evolution favours more modest bids, and a resurgence of global cities and historical Olympic host cities within the Olympic landscape.
BOOK
Strong within-host selection in a maternally inherited obligate symbiont
Numerous animal lineages have maternally inherited symbionts that are required for host reproduction and growth. Endosymbionts also pose a risk to their hosts because of the mutational decay of their genomes through genetic drift or to selfish mutations that favor symbiont fitness over host fitness. One model for heritable endosymbiosis is the association of aphids with their obligate bacterial symbiont, Buchnera. We experimentally established heteroplasmic pea aphid matrilines containing pairs of closely related Buchnera haplotypes and used deep sequencing of diagnostic markers to measure haplotype frequencies in successive host generations. These frequencies were used to estimate the effective population size of Buchnera within hosts (i.e., the transmission bottleneck size) and the extent of within-host selection. The within-host effective population size was in the range of 10 to 20, indicating a strong potential for genetic drift and fixation of deleterious mutations. Remarkably, closely related haplotypes were subject to strong within-host selection, with selection coefficients as high as 0.5 per aphid generation. In one case, the direction of selection depended on the thermal environment and went in the same direction as between-host selection. In another, a new mutant haplotype had a strong within-host advantage under both environments but had no discernible effect on host-level fitness under laboratory conditions. Thus, within-host selection can be strong, resulting in a rapid fixation of mutations with little impact on host-level fitness. Together, these results show that within-host selection can drive evolution of an obligate symbiont, accelerating sequence evolution.
Journal Article
Manipulation of Insect Vectors’ Host Selection Behavior by Barley Yellow Dwarf Virus Is Dependent on the Host Plant Species and Viral Co-Infection
Previous studies have shown that vector-borne viruses can manipulate the host selection behavior of insect vectors, yet the tripartite interactions of pathogens, host plants and insect vectors have been documented only in a limited number of pathosystems. Here, we report that the host selection behavior of the insect vector of barley yellow dwarf virus-PAV (BYDV-PAV) and cereal yellow dwarf virus-RPS (CYDV-RPS) is dependent on the host plant species and viral co-infection. This study shows that a model cereal plant, Brachypodium distachyon, is a suitable host plant for examining tripartite interactions with BYDV-PAV and CYDV-RPS. We reveal that BYDV-PAV has a different effect on the host selection behavior of its insect vector depending on the host plant species. Viruliferous aphids significantly prefer non-infected plants to virus-infected wheat plants, whereas viral infection on a novel host plant, B. distachyon, is not implicated in the attraction of either viruliferous or nonviruliferous aphids. Furthermore, our findings show that multiple virus infections of wheat with BYDV-PAV and CYDV-RPS alter the preference of their vector aphid. This result indicates that BYDV-PAV acquisition alters the insect vector’s host selection, thereby varying the spread of multiple viruses.
Journal Article
Innate preference hierarchies coupled with adult experience, rather than larval imprinting or transgenerational acclimation, determine host plant use in Pieris rapae
The evolution of host range drives diversification in phytophagous insects, and understanding the female oviposition choices is pivotal for understanding host specialization. One controversial mechanism for female host choice is Hopkins’ host selection principle, where females are predicted to increase their preference for the host species they were feeding upon as larvae. A recent hypothesis posits that such larval imprinting is especially adaptive in combination with anticipatory transgenerational acclimation, so that females both allocate and adapt their offspring to their future host. We study the butterfly Pieris rapae, for which previous evidence suggests that females prefer to oviposit on host individuals of similar nitrogen content as the plant they were feeding upon as larvae, and where the offspring show higher performance on the mother's host type. We test the hypothesis that larval experience and anticipatory transgenerational effects influence female host plant acceptance (no‐choice) and preference (choice) of two host plant species (Barbarea vulgaris and Berteroa incana) of varying nitrogen content. We then test the offspring performance on these hosts. We found no evidence of larval imprinting affecting female decision‐making during oviposition, but that an adult female experience of egg laying in no‐choice trials on the less‐preferred host Be. incana slightly increased the P. rapae propensity to oviposit on Be. incana in subsequent choice trials. We found no transgenerational effects on female host acceptance or preference, but negative transgenerational effects on larval performance, because the offspring of P. rapae females that had developed on Be. incana as larvae grew slower on both hosts, and especially on Be. incana. Our results suggest that among host species, preferences are guided by hard‐wired preference hierarchies linked to species‐specific host traits and less affected by larval experience or transgenerational effects, which may be more important for females evaluating different host individuals of the same species. The importance of nongenetic inheritance through transgenerational acclimation has received increasing attention. Very few studies have investigated the role of transgenerational effects in the adult host plant preference and larval performance of phytophagous insects, even though these traits are explaining host‐driven diversification in this hyperdiverse group.
Journal Article
Host-Plant Selection Behavior of Ophraella communa, a Biocontrol Agent of the Invasive Common Ragweed Ambrosia artemisiifolia
Understanding the host-selection behavior of herbivorous insects is important to clarify their efficacy and safety as biocontrol agents. To explore the host-plant selection of the beetle Ophraella communa, a natural enemy of the alien invasive common ragweed (Ambrosia artemisiifolia), we conducted a series of outdoor choice experiments in cages in 2010 and in open fields in 2010 and 2011 to determine the preference of O. communa for A. artemisiifolia and three non-target plant species: sunflower (Helianthus annuus), cocklebur (Xanthium sibiricum), and giant ragweed (Ambrosia trifida). In the outdoor cage experiment, no eggs were found on sunflowers, and O. communa adults rapidly moved from sunflowers to the other three plant species. Instead, adults preferred to lay eggs on A. artemisiifolia, followed by X. sibiricum and A. trifida, although very few eggs were observed on A. trifida. Observing the host-plant selection of O. communa in an open sunflower field, we found that O. communa adults always chose A. artemisiifolia for feeding and egg laying. Although several adults (<0.02 adults/plant) stayed on H. annuus, no feeding or oviposition were observed, and adults quickly transferred to A. artemisiifolia. In 2010 and 2011, 3 egg masses (96 eggs) were observed on sunflowers, but they failed to hatch or develop into adults. In addition, some O. communa adults crossed the barrier formed by H. annuus to feed and oviposit on A. artemisiifolia planted in the periphery, and persisted in patches of different densities. Additionally, only 10% of O. communa adults chose to feed and oviposit on the X. sibiricum barrier. These findings suggest that O. communa poses no threat to the biosafety of H. anunuus and A. trifida and exhibits a robust dispersal capacity to find and feed on A. artemisiifolia. However, X. sibiricum has the potential to be an alternative host plant for O. communa.
Journal Article
Host selection behavior of Spodoptera exigua (Lepidoptera: Noctuidae, Hübner, 1808) in response to Rosmarinus officinalis (Lamiales: Lamiaceae, Linnaeus, 1753) volatiles
Plant volatiles play an important role as cues for herbivorous insects in search of resources, mates, and oviposition sites in complex environments. The use of plant volatiles as attractants or repellents can be utilized to monitor and control pest populations.
Spodoptera exigua
(Lepidoptera: Noctuidae, Hübner, 1808) is a highly destructive pest of cruciferous crops that has developed resistance to a variety of insecticides, making the management challenging. This study aimed to investigate the behavioral response of the pest to volatile organic compounds (VOCs) emitted by
Rosmarinus officinalis
(Lamiales: Lamiaceae, Linnaeus, 1753). We identified ten compounds from the rosemary using gas chromatography-electroantennographic detection (GC-EAD). We then subjected these compounds to ovipositional and olfactory bioassays. The results revealed that the moths were significantly attracted to seven compounds while being repelled by the others. In oviposition bioassays, linalool showed the greatest attractive effect at 69.97% (
P
< 0.001) at 15,000 μg·mL
−1
, while eucalyptol exhibited the highest repellent rate at 47.11% (
P
< 0.01) at 1500 μg·mL
−1
. In olfactory bioassays,
β
-pinene showed high attractiveness at a concentration of 150 μg·mL
−1
, with the attractive rate of 66.67% (
χ
2
= 8.64, d
f
= 1,
P
= 0.001). Eucalyptol again displayed strong repellent activity at 42.86% (
χ
2
= 5.14, d
f
= 1,
P
= 0.023) at a concentration of 1500 μg·mL
−1
. Furthermore, these compounds elicited a dose–response from the moth in these bioassays. This study demonstrates the theoretical feasibility of using rosemary as an attractive crop in agricultural fields for the environmentally friendly management of beet armyworms. However, when VOCs are applied in the field, they often experience significant dilution, resulting in behaviors much less than those observed in the lab. Therefore, these compounds require testing in field settings to ensure their viability as a management strategy for insects.
Journal Article