Search results for "Mel"

First extensive characterization of the venom gland from an egg parasitoid: structure, transcriptome and functional role.

2018

The venom gland is a ubiquitous organ in Hymenoptera. In insect parasitoids, the venom gland has been shown to have multiple functions including regulation of host immune response, host paralysis, host castration and developmental alteration. However, the role played by the venom gland has been mainly studied in parasitoids developing in larval or pupal hosts while little is known for parasitoids developing in insect eggs. We conducted the first extensive characterization of the venom of the endoparasitoid Ooencyrtus telenomicida (Vassiliev), a species that develops in eggs of the stink bug Nezara viridula (L.). In particular we investigated the structure of the venom apparatus, its functio…

Oxylipin mediated stress response of a miraculin-like protease inhibitor in Hexanoic acid primed eggplant plants infested by Colorado potato beetle

2017

Insect-plant interactions are governed by a complex equilibrium between the mechanisms through which plant recognize insect attack and orchestrate downstream signaling events that trigger plant defense responses, and the mechanisms by which insects overcome plant defenses. Due to this tight and dynamic interplay, insight into the nature of the plant defense response can be gained by analyzing changes in the insect herbivores digestive system upon plant feeding. In this work we have identified a Solanum melongena miraculin-like protease inhibitor in the midgut juice of Colorado potato larvae feeding on eggplant plants treated with the natural inducer of plant defenses hexanoic acid. We analy…

Enemy recognition is linked to soldier size in a polymorphic stingless bee

2017

Many ant and termite colonies are defended by soldiers with powerful mandibles or chemical weaponry. Recently, it was reported that several stingless bee species also have soldiers for colony defence. These soldiers are larger than foragers, but otherwise lack obvious morphological adaptations for defence. Thus, how these soldiers improve colony fitness is not well understood. Robbing is common in stingless bees and we hypothesized that increased body size improves the ability to recognize intruders based on chemosensory cues. We studied the Neotropical species Tetragonisca angustula and found that large soldiers were better than small soldiers at recognizing potential intruders. Larger so…

Improved sampling at the subspecies level solves a taxonomic dilemma – A case study of two enigmatic Chinese tit species (Aves, Passeriformes, Parida…

2017

Abstract A recent full species-level phylogeny of tits, titmice and chickadees (Paridae) has placed the Chinese endemic black-bibbed tit (Poecile hypermelaenus) as the sister to the Palearctic willow tit (P. montanus). Because this sister-group relationship is in striking disagreement with the traditional affiliation of P. hypermelaenus close to the marsh tit (P. palustris) we tested this phylogenetic hypothesis in a multi-locus analysis with an extended taxon sampling including sixteen subspecies of willow tits and marsh tits. As a taxonomic reference we included type specimens in our analysis. The molecular genetic study was complemented with an analysis of biometric data obtained from mu…

Curse of the black spot: spotting negatively correlates with fitness in black grouseLyrurus tetrix

2016

There is growing evidence that achromatic plumage can act as honest indicators of male quality. In some species with areas of white plumage, black melanin spots can be found on parts of the feathers. The functional significance of these spots and the relationship with male quality is yet poorly understood. We investigated the relationship between black melanin spots in an otherwise totally white ornament, the undertail covert, in relation to age, fitness and covariance with past and present expression of sexual traits, in the lekking black grouse Lyrurus tetrix. We found that spots at tips of feathers (tip spots) were negatively related to survival and reproductive success, and covaried neg…

The “unguarded-X” and the genetic architecture of lifespan: Inbreeding results in a potentially maladaptive sex-specific reduction of female lifespan…

2018

Sex differences in ageing and lifespan are ubiquitous in nature. The "unguarded-X" hypothesis (UXh) suggests they may be partly due to the expression of recessive mutations in the hemizygous sex chromosomes of the heterogametic sex, which could help explain sex-specific ageing in a broad array of taxa. A prediction central to the UX hypothesis is that inbreeding will decrease the lifespan of the homogametic sex more than the heterogametic sex, because only in the former does inbreeding increase the expression of recessive deleterious mutations. In this study, we test this prediction by examining the effects of inbreeding on the lifespan and fitness of male and female Drosophila melanogaster…

Sperm Quality Assessment in Honey Bee Drones

2020

The quality of honey bee drone semen is relevant in different contexts, ranging from colony productivity to pathology, toxicology and biodiversity preservation. Despite its importance, considerably less knowledge is available on this subject for the honey bee when compared to other domestic animal species. A proper assessment of sperm quality requires a multiple testing approach which discriminates between the different aspects of sperm integrity and functionality. Most studies on drone semen quality have only assessed a few parameters, such as sperm volume, sperm concentration and/or sperm plasma membrane integrity. Although more recent studies have focused on a broader variety of aspects …

Does silica concentration and phytolith ultrastructure relate to phytolith hardness?

2017

Abstract Grasses are an important part of the forage of many herbivorous mammals and their phytoliths have long been regarded as the most important agent of tooth wear. Recent work has challenged this “paradigm” in finding evidence 1. of native phytoliths to be much softer then tooth enamel and 2. indicating, that phytolith hardness is highly variable, 3. prone to methodology and 4. not easy to be related to habitat conditions. We conduct controlled silica-cultivations measuring SiO2 content in the common forage grass Themeda triandra. Phytoliths are extracted natively, and nano-indentation values are measured. Phytolith hardness in Themeda triandra is found to be independent of silicate av…

Evaluating responses to temperature during pre-metamorphosis and carry-over effects at post-metamorphosis in the wood tiger moth (Arctia plantaginis)

2019

Insect metamorphosis is one of the most recognized processes delimiting transitions between phenotypes. It has been traditionally postulated as an adaptive process decoupling traits between life stages, allowing evolutionary independence of pre- and post-metamorphic phenotypes. However, the degree of autonomy between these life stages varies depending on the species and has not been studied in detail over multiple traits simultaneously. Here, we reared full-sib larvae of the warningly coloured wood tiger moth ( Arctia plantaginis ) in different temperatures and examined their responses for phenotypic (melanization change, number of moults), gene expression (RNA-seq and qPCR of candidate ge…

2018

BackgroundThe insect cuticle covers the whole body and all appendages and has bi-directionnal selective permeability: it protects against environmental stress and pathogen infection and also helps to reduce water loss. The adult cuticle is often associated with a superficial layer of fatty acid-derived molecules such as waxes and long chain hydrocarbons that prevent rapid dehydration. The waterproofing properties of cuticular hydrocarbons (CHs) depend on their chain length and desaturation number.DrosophilaCH biosynthesis involves an enzymatic pathway including several elongase and desaturase enzymes.MethodsThe link between desiccation resistance and CH profile remains unclear, so we tested…