Search results for " Entomology"
showing 10 items of 285 documents
Effect of host kairomones and oviposition experience on the arrestment behavior of an egg parasitoid
2006
SUMMARY Chemical residues left by walking adults of the southern green stink bug, Nezara viridula (L.) (Heteroptera: Pentatomidae) induce arrestment behavior in the egg parasitoid Trissolcus basalis (Wollaston)(Hymenoptera: Scelionidae) leading to prolonged periods of walking on contaminated areas and to systematic return to the stimulus after encountering the treatment borders. In this study, we quantified how the hierarchical value of residues from host adults and oviposition experience can influence the arrestment behavior of T. basalis females. Our results showed that:(1) female wasps perceived host residues at different hierarchical levels depending on the host gender, with a clear pre…
Virgins in the wild: mating status affects the behavior of a parasitoid foraging in the field
2008
In haplodiploid organisms, virgin females can produce offspring, albeit only sons. They may therefore face a trade-off between either: (1) searching for hosts and producing sons immediately; or (2) searching for mates and perhaps producing both sons and daughters later in life. Although this trade-off raises a theoretical interest, it has not been approached experimentally. The objective of this article is thus to document the effect of mating status on the foraging behavior of a haplodiploid parasitoid. For this, we recorded the behavior of virgin and mated female Lysiphlebus testaceipes (Hymenoptera: Braconidae) after being released, in the field, on a colony of their aphid hosts. Half of…
Biological and life table parameters of Typhlodromus laurentii and Iphiseius degenerans (Acari, Phytoseiidae) fed on Panonychus citri and pollen of O…
2015
Typhlodromus laurentii and Iphiseius degenerans are two generalist phytoseiid mites, broadly spread in the Mediterranean area, especially in citrus orchards. In the present work we report results on various biological and life table parameters of the two phytoseiids, fed on pollen of Oxalis pes-caprae and various stages of the tetranychid Panonychus citri. Iphiseius degenerans had the shortest post embryonic development (6.53 days), the highest oviposition rate (1.83 eggs/female/day) and the shortest mean time between eggs laid (0.55 day) on Oxalis pollen, whereas the two food types did not influence these parameters in T. laurentii. However, Oxalis pollen showed a positive effect on the su…
Description of Dryocosmus destefanii new species (Hymenoptera: Cynipidae: Cynipini) from Quercus suber L. in Italy
2018
A new species, Dryocosmus destefanii Cerasa & Melika n. sp. associated with a Cerris section oak, Quercus suber L., is described from Italy. Description, diagnosis, host associations and biology for the new species and an illustrated identification key to the Western Palaearctic Dryocosmus species are given. The description is supported by morphological and molecular data.
Attraction of egg-killing parasitoids toward induced plant volatiles in a multi-herbivore context
2015
In response to insect herbivory, plants emit volatile organic compounds which may act as indirect plant defenses by attracting natural enemies of the attacking herbivore. In nature, plants are often attacked by multiple herbivores, but the majority of studies which have investigated indirect plant defenses to date have focused on the recruitment of different parasitoid species in a single-herbivore context. Here, we report our investigation on the attraction of egg parasitoids of lepidopteran hosts (Trichogramma brassicae and T. evanescens) toward plant volatiles induced by different insect herbivores in olfactometer bioassays. We used a system consisting of a native crucifer, Brassica nigr…
Chemistry of pheromonal and defensive secretions in the nymphs and the adults ofDysdercus cingulatus Fabr. (Heteroptera, Pyrrhocoridae)
1991
59 ref.; International audience; The exocrine secretions from the nymphs and the adults of both sexes in D. cingulatus were chemically investigated. Seven compounds were identified in the anterior glands, and eleven in the median dorsoabdominal glands of nymphs and adults of both sexes. Fifty-five compounds were identified in the defensive glands (34 in posterior dorsoabdominal glands ofnymphs and 21 in metathoracic glands of adults), and six in the sternal glandular epithelium of the males. The biological function of the glandular secretions and of their identified compounds were investigated and are discussed.
Pre-invasion history and demography shape the genetic variation in the insecticide resistance-related acetylcholinesterase 2 gene in the invasive Col…
2012
Abstract Background Invasive pest species offers a unique opportunity to study the effects of genetic architecture, demography and selection on patterns of genetic variability. Invasive Colorado potato beetle (Leptinotarsa decemlineata) populations have experienced a rapid range expansion and intense selection by insecticides. By comparing native and invasive beetle populations, we studied the origins of organophosphate (OP) resistance-associated mutations in the acetylcholinesterase 2 (AChE2) gene, and the role of selection and demography on its genetic variability. Results Analysis of three Mexican, two US and five European populations yielded a total of 49 haplotypes. Contrary to the exp…
Ground-level predation on artificial caterpillars indicates no enemy-free time for lepidopteran larvae
2017
Lepidoptera is one of the most diverse orders of insects, their larvae are very abundant in many habitats, and frequent prey of various predators. To decrease predation risk, caterpillars developed several means of defence, among them timing their activity to avoid predators (seeking enemy-free time). Although the enemy-free time hypothesis is often invoked to explain caterpillar behaviour, empirical evidence for it is scarce. We tested whether such enemy-free time exists in a temperate forest by comparing predation pressure on artificial caterpillars during day and night on the ground in forest fragments in Denmark. We found a high predation rate, 23.9% d(-1), and higher predation rate at …
Revision of the genus Trogulus Latreille: the Trogulus coriziformis species-group of the western Mediterranean (Opiliones:Trogulidae)
2008
Within the well researched European fauna of harvestmen, the genus Trogulus Latreille exhibits unexpectedly high cryptic diversity. The species’ uniform morphology hinders an exclusively morphological approach to their systematics and taxonomy, and a preliminary molecular study estimated the number of species to be three times higher than currently known. The current study focuses on a clearly defined species-group within Trogulus, combining molecular (~1700 bp 28S rRNA and the cytochrome b gene), distributional, morphometric and morphological data. Relationships are reconstructed using Bayesian inference, maximum parsimony and maximum likelihood and this information is subsequently used t…
World revision of the genus Encyrtoscelio Dodd (Hymenoptera: Scelionidae)
1995
The genus Encyrtoscelio Dodd is revised. E. apterus (Szelényi), E. mirissimus Dodd, E. turneri Waterston are redescribed, and six new species are described: E. cydni Caleca, E. japonicus Caleca, E. mediterraneus Caleca, E. miroides Caleca, E. spuratus Caleca and E. undecim Caleca. A key to separate females is presented, and is based on the number of antennomeres and claval sensillar formula, mandibular spurs and teeth, palpal formula and clypeus, and some cephalic characters. Morphological adaptations of the head and mandibles are discussed in relation to host habitat and oviposition site. Information on host associations, habitat preference, seasonal and daily occurrence of some species a…