Search results for "leaf beetle"
showing 10 items of 10 documents
Exploring species-level taxonomy in the Cryptocephalus flavipes species complex (Coleoptera: Chrysomelidae)
2016
In insects, morphological species identification is often challenging. The discrimination of closely related species may be hampered when only subtle differences in phenotypic characters or a continuum in their variability are present. This is exemplified in the Cryptocephalus flavipes species complex (Coleoptera; Chrysomelidae) where, until now, the species have been discriminated only by the yellow pattern on frons, pronotum, and epipleurae. In the present study, the phylogeny of the C. flavipes species complex was resolved through a multi-locus sequence approach, and the inclusion in the group of the phenotypically similar Cryptocephalus quadripustulatus Gyllenhal, 1813 was evaluated. Su…
Conservation genetics of highly isolated populations of the xerothermic beetleCrioceris quatuordecimpunctata(Chrysomelidae)
2012
Xerothermic species are rare and threatened in central and eastern Europe. In light of the continuing loss of steppe-like habitats due to anthropogenic fragmentation and degradation, the evaluation of genetic variation in populations inhabiting them is of immediate importance if appropriate conservation measures are to be undertaken. Here we report on the genetic diversity of the rare leaf beetle Crioceris quatuordecimpunctata, whose populations in central and eastern Europe inhabit highly geographically isolated areas. All of the studied populations (in Poland, Ukraine, and Slovakia) were differentiated at the mitochondrial marker COI. However, with respect to the nuclear marker ITS1, Poli…
Safety in Numbers: How Color Morph Frequency Affects Predation Risk in an Aposematic Moth
2021
Polymorphic warning signals in aposematic systems are enigmatic because predator learning should favor the most common form, creating positive frequency-dependent survival. However, many populations exhibit variation in warning signals. There are various selective mechanisms that can counter positive frequency-dependent selection and lead to temporal or spatial warning signal diversification. Examining these mechanisms and their effects requires first confirming whether the most common morphs are favored at both local and regional scales. Empirical examples of this are uncommon and often include potentially confounding factors, such as a lack of knowledge of predator identity and behavior. …
Experimental evidence suggests that specular reflectance and glossy appearance help amplify warning signals
2017
AbstractSpecular reflection appears as a bright spot or highlight on any smooth glossy convex surface and is caused by a near mirror-like reflectance off the surface. Convex shapes always provide the ideal geometry for highlights, areas of very strong reflectance, regardless of the orientation of the surface or position of the receiver. Despite highlights and glossy appearance being common in chemically defended insects, their potential signalling function is unknown. We tested the role of highlights in warning colouration of a chemically defended, alpine leaf beetle, Oreina cacaliae. We reduced the beetles’ glossiness, hence their highlights, by applying a clear matt finish varnish on thei…
Interactions between willows and insect herbivores under enhanced ultraviolet-B radiation
2002
We studied the effects of elevated ultraviolet-B radiation on interactions between insect herbivores and their host plants by exposing two species of phytochemically different willows, Salix myrsinifolia and S. phylicifolia, to a modulated increase in ultraviolet radiation in an outdoor experiment and monitoring the colonisation of insect herbivores on these willows. We examined the effect of increased ultraviolet-B (UV-B) radiation on (1) the quality of willow leaves, (2) the distribution and abundance of insect herbivores feeding on these willows, (3) the resulting amount of damage, and (4) the performance of insect larvae feeding on the exposed plant tissue. Six clones of each of the two…
Plant-herbivorous beetle networks : molecular characterization of trophic ecology within a threatened steppic environment
2015
DNA barcoding facilitates many evolutionary and ecological studies, including the examination of the dietary diversity of herbivores. In this study, we present a survey of ecological associations between herbivorous beetles and host plants from seriously threatened European steppic grasslands. We determined host plants for the majority (65%) of steppic leaf beetles (55 species) and weevils (59) known from central Europe using two barcodes (trnL and rbcL) and two sequencing strategies (Sanger for mono/oligophagous species and Illumina for polyphagous taxa). To better understand the ecological associations between steppic beetles and their host plants, we tested the hypothesis that leaf beetl…
Do female leaf beetles Galerucella nymphaeae choose their mates and does it matter?
1998
The role of active female choice in sexual selection is frequently difficult to ascertain, and this is particularly the case for many insect species. Also, it is uncertain whether choosing between males would affect offspring viability. We designed an experiment to investigate the presence of female choice in a Coleoptera species (Galerucella nymphaeae). We also estimated whether mate choice would have any effect on offspring performance. Females were first placed with two males in a test arena to see which of the males copulated with the virgin female, and how quickly. Subsequently the loser male was offered a new virgin female to test for any change in latency time until mating. The two-m…
Egg and larval load assessment and its influence on oviposition behaviour of the leaf beetle Galerucella nymphaeae
1993
The oviposition behaviour of the water-lily beetle Galerucella nymphaeae was examined. This species is a specialist herbivore on the floating leaves of nymphaeids Nymphaeaceae and especially on the yellow water-lily, Nuphar lutea. Females lay their eggs in clutches on the leaves, and after hatching, the larvae feed on the leaves. The quality of the leaves decreases quickly after the larvae hatch, and eventually the leaves will sink below the water surface, whereupon the eggs, 1st-instar larvae and pupae are killed by drowning. The influence of conspecific eggs, larvae and feeding tracks on the oviposition preferences of the beetles was tested. Females were allowed to choose between fresh le…
La lutte biologique contre l'ambroisie à feuilles d'armoise illustrée par l'exemple d'Ophraella communa: quels intérêts et quelles limites ?
2016
National audience; Common ragweed (Ambrosia artemisiifolia) was introduced in France over 150 years ago and its spreading across France now seems inexorable. The specific biology of this summer annual creates new problems for the managers of the various habitats where the plant can be found. The reduced possibility, or even the impossibility, to use traditional control means in certain environment conditions brings managers to consider biological control as one of the few possible means for slowing down the spread, or even pushing back the distribution area, of this invasive and allergenic plant. With Ophraella communa as an example, a reflection is presented on the benefit-risk balance of …
Energy metabolism and metabolic rate of the alder leaf beetle Agelastica alni (L.) (Coleoptera, Chrysomelidae) under aerobic and anaerobic conditions…
2003
In early fall, adult alder leaf beetles (Agelastica alni L.) retreat, for overwintering, to the top layer of the soil near their forage trees where the ground gets easily waterlogged so that the beetles will be submerged and cut off from atmospheric oxygen. Hence, unlike most other adult insects, alder leaf beetles encounter hypoxia/anoxia in their natural habitat and this may occur at moderate temperature. Exposing beetles to pure nitrogen gas at 20 degrees C had similar behavioral and metabolic effects as submerging them in water, causing rapid immobility and increasing the content of lactate about sevenfold to some 5mgr;molg(-1) body weight during 10h anoxia. Recovery from 10 h hypoxia/a…