Natural and sexual selection become visible : Animal – Plant interactions between the parasitic weevil Rhopalapion longirostre (original) (raw)
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Bonn zoological Bulletin, 2010
Multivariate statistics (principal components analysis, path analysis) were used to investigate fitness compo- nents of the interactions between the weevil Rhopalapion longirostre (Olivier, 1807), Apionidae, Coleoptera and its host plant Alcea rosea (Linnaeus, 1758), Malvaceae. We focused on the activities of the larvae such as the choice of seeds for consumption, the preparation of seed chambers as a site for pupation, as well as the construction of escape holes through which the adults later emerge. The analyses revealed that the optimal conditions for successful development of the weevils depended on the availabil- ity of seed capsules characterized by a high number of well developed seeds, few undeveloped and few spoiled seeds. The high number of larvae, pupae and not emerged adults found in the seed capsules corresponds with the successful emergence of adults. Egg deposition by the females in appropriate flower buds of the host plant, together with larval con- tribution to over...
Acta Oecologica-international Journal of Ecology, 1999
Palm pollination can be quite diverse but has been poorly studied. This paper describes the life cycle of Derelomus chamaeropsis, a Coleoptera that inhabits the inflorescences of the Mediterranean dwarf palm Chamaerops humilis. D. chamaeropsis is specific to Chamaerops inflorescences, where it eats pollen and the rachis of inflorescences on pistillate plants. They usually lay eggs only on staminate inflorescences where larvae develop and bore into the inflorescence rachis. Larvae do not develop on pistillate inflorescences, except for cases with almost no fruit development. Pistillate plants can thus protect themselves from weevil predation. When visiting pistillate inflorescences, weevils can feed on rachis but usually do not find the brood place reward. Pollination is thus by deceit and weevils should be selected to avoid pistillate inflorescences. D. chamaeropsis pupate within the rachis of staminate inflorescences, but disperse before collecting pollen, thus staminate plants do not have an individual advantage in breeding weevils. However, because larvae develop on dead tissues, the costs of larval development are likely to be low for the plant. This study provides a new example of pollination symbiosis where the pollinator develops on the plant it pollinates, and illustrates how the evolutionary functioning of such relationships can be diverse. © 1999 Éditions scientifiques et médicales Elsevier SAS
2021
1. The reproduction of specialised endophagous insects relies on a fine temporal synchronization between the insect and its host plant phenology. 2. Since the spatial distribution and local prevalence of specialised insects depend on both environmental conditions and biotic interactions, in this study, we assessed whether the life cycle of the predispersal seed feeding weevil, Hemicolpus abdominalis (Curculionidae), is synchronised with the reproductive phenology of its host plant, Tocoyena formosa (Rubiaceae) in the Brazilian Cerrado. Following an ecological niche modelling approach, we also tested whether the predicted distribution of this specialised weevil matches that of its host plant. 3. We observed a tight synchronization between the weevil reproduction and its host plant reproductive phenology. After emergence from the fruits, adult weevils enter in reproductive diapause, with reproductive development resuming in the next reproductive season, which indicates the univoltism of this species. 4. There was a high spatial congruence in the distribution of H. abdominalis and its host plant. Since the reproduction of H. abdominalis is synchronised with the host plant phenology, temporal mismatches between the weevil life cycle, and plant reproduction may affect the long-term population prevalence of the insect. 5. The life cycle of the predispersal seed feeding weevil, H. abdominalis, depends on a close match with the host plant reproductive phenology, whose fruit production is entirely dependent on long-tongued hawkmoth pollinators. Hence, we highlight the importance of both biotic and abiotic conditions in shaping the distribution range of a specialised endophagous insect.
Weevil Impacts of Wild Indigo Weevil on Seed Production in Longbract Wild Indigo
2010
Seeds of many species of Baptisia are eaten by larvae of the wild indigo weevil Apion rostrum, impacting plant fitness and compromising prairie restoration activities. We examined the impacts of A. rostrum predation on seed output in a commercial seed production population of longbract wild indigo Baptisia bracteata in southeastern Minnesota. Predehiscent seed pods (n = 673) were collected from 15 plants in September 2007, measured (total pod length), and examined for intact seeds, damaged seeds, and weevils. Adult weevils were present in 46% of pods examined, averaging 1.53 weevils/predated pod. More than 40% of predated pods contained two or more weevils. Pods contained an average of 9 seeds each, but two-thirds of the seeds failed to develop properly or were damaged by predation and/or fungus (possibly introduced by ovipositing weevils). Non-predated seed pods averaged 10 X more undamaged seeds than did predated seed pods (5.14 vs. 0.48 seeds/pod). Predated pods averaged 0.25 cm ...
Functional Ecology, 2001
1. Natural enemies are likely to influence the interactions between herbivorous insects and their host plants. In particular, selection exerted by natural enemies could favour host-plant switches and cause, or maintain, oviposition preference for a host species that is nutritionally inferior to another acceptable host. 2. In a previous study, it was shown that larvae of the leaf beetle Oreina elongata perform better on Adenostyles alliariae (Asteraceae) than on Cirsium spinosissimum (Asteraceae). Moreover, A. alliariae provides larval and adult beetles with sequestrable chemical defences. However, in the field, egg densities are much higher on C. spinosissimum than on adjacent A. alliariae . 3. In this study, it was investigated whether this oviposition pattern could be maintained by C. spinosissimum , providing the eggs of O. elongata with better protection from natural enemies. In a field experiment, the survival of eggs was quantified on plants of each of the two species, with and without enemy exclusion. 4. Egg survival was equal for both host species when enemies were excluded from the plants, but it was higher on C. spinosissimum than on A. alliariae when enemies were allowed to the plants. It was also experimentally tested whether the higher egg densities observed in the field on C. spinosissimum are actually due to oviposition preference by the beetle. In a no-choice test, females laid more eggs on C. spinosissimum than on A. alliariae . 5. It can thus be confirmed that C. spinosissimum is really preferred for oviposition and it is concluded that this preference is likely to be maintained, at least partly, by a higher egg survival on C. spinosissimum due to enemy-free space provided by this host plant.
Biological Journal of the Linnean Society, 2011
Extreme sexually dimorphic phenotypes are frequently attributed to strong sexual selection but they can also arise as a consequence of different ecological demands. The evolutionary emergence of elongated rostra was a key event in the adaptive radiation of weevils. Exaggerated female rostra evolved in numerous weevil taxa, enabling females to bore long channels for egg deposition into various parts of host plants. The investigated ecological scenario involves three species of brentid weevils, all associated with the same host plant, Alcea rosea. The present study reveals that: (1) Rhopalapion longirostre bores egg channels into the buds, and the female rostrum is twice as long and its surface is smoother than in the male; (2) Alocentron curvirostre and Aspidapion validum live on the same host plant but use the stems for egg deposition; in these species, female rostra are not exaggerated; (3) the females of all three species possess a stronger mandible musculature than males; (4) the elongated female snout of R. longirostre is a response to the requirements of boring egg channels of maximal depth into the buds of the host plant; and (5) female muscle strength is an adaptation to boring into hard plant tissues, irrespective of rostrum length.
Biological Invasions, 2011
Mechanisms underlying invasive species impacts remain incompletely understood. We tested the hypothesis that priority resource access by an invasive biocontrol weevil, Rhinocyllus conicus, intensifies and alters the outcome of competition with native floral herbivores over flower head resources of the non-target, native host plant Cirsium canescens, specifically with the predominant, synchronous tephritid fly Paracantha culta. Four main results emerged. First, we documented strong, asymmetric competition, with R. conicus out-competing P. culta. Second, weevil priority access to floral resources accelerated competitive suppression of P. culta. Evidence for competitive suppression with increased weevil priority included decreases in both the numbers and the total biomass of native flies, plus decreases in individual P. culta fly mass and, so, potential fitness. Third, we found evidence for three concurrent mechanisms underlying the competitive suppression of P. culta by R. conicus. Prior use of a flower head by R. conicus interfered with P. culta pre-oviposition behavior. Once oviposition occurred, the weevil also reduced fly post-oviposition performance. Preemptive resource exploitation occurred, shown by the significant effect of flower head size on the total number of insects developing and in the magnitude of R. conicus effects on P. culta. Interference also occurred, shown by a spatial shift of surviving P. culta individuals away from the preferred receptacle resources as R. conicus priority increased. Finally, fourth, using an individual-based model (IBM), we found that the competitive interactions documented have the potential for imposing demographic consequences, causing a reduction in P. culta population sizes. Thus, priority resource access by an invasive insect increased competitive impact on the predominant native insect in the invaded floral guild. This study also provides the Electronic supplementary material The online version of this article (
The effect of spatial scale on interactions between two weevils and their food plant
Acta Oecologica, 1999
The effect of spatial scale on the interactions between the weevils Gymnetron pascuorum Gyll. and Mecinus pyraster Herbst and their host plant, ribwort plantain Plantago lanceolata L., was studied. Both weevils developed in plantain seedheads but occupied different niches within the seedhead. Seedheads were sampled annually from 162 plants at each of two experimental sites consisting of a series of habitat patches of two distinct sizes. Data were analysed from three site-years. Our results suggest that the density of available seedheads varied among years and this had a direct effect on abundance. M. pyraster, which develops in the stem within the seedhead, was more sensitive to changes in seedhead density than was G. pascuorum, which develops within the seeds themselves. The presence of a hedgerow along one side of the experimental site affected the pattern of colonisation of newly-created habitat patches by G. pascuorum but not by M. pyraster. Changes in spatial scale did not affect the variability of seedhead and insect densities. G. pascuorum had an aggregated distribution at all the spatial scales considered, but the distribution of M. pyraster was very scale dependent. The distributions of the two weevil species were positively associated amongst infested plants but not amongst infested seedheads. Behavioural and ecological factors that could explain the results of the data analyses are discussed.