Search results for "Insect Science"
showing 10 items of 1011 documents
Characteristics of the spermathecal contents of old and young honeybee queens.
2009
Sperm are often stored, for a long time after mating, in females of various animal species. In case of the queen honeybee (Apis mellifera), sperm remain fertile for several years in the spermatheca. Little information is available regarding the effect of long-term storage of sperm on its fertility. To evaluate this, enzymes and/or sperm have been analysed from the spermatheca of 75 queens of various ages (0 year Y0, n=14; one year Y1, n=14; two years Y2, n=7; virgin queen VQ, n=40) and semen samples have been taken from 46 drones. The sperm from the spermatheca of older queens move more slowly (F=11.45, P < 0.0001) and show different movement patterns (Chi2=90.0, P < 0.0001) from those of t…
Photoperiodic regulation of cold tolerance and expression levels of regucalcin gene in Drosophila montana
2011
Temperature-induced plasticity of cold tolerance has been reported in many insect species, but cold tolerance can also be affected by changes in day (or night) length. In the present study we elucidate the direct and indirect effects of photoperiod on the cold tolerance of females of two Drosophila montana strains--one which possesses a robust photoperiodic diapause and another which does not. In the diapause-strain the time needed for recovery from chill coma showed a positive correlation with day length, but diapause itself played only a minor role in photoperiodic acclimation. The strain that was not able to enter to diapause as a response to day length also lacked photoperiodic cold acc…
Female-released sex pheromones mediating courtship behavior in Lysiphlebus testaceipes males.
2013
Ethological aspects and chemical communication at close-range between the sexes of Lysiphlebus testaceipes Cresson (Hymenoptera: Braconidae) have been investigated through behavioral bioassays and chemical analysis. The attractiveness toward males of whole-body extracts of females and males in hexane and acetone was evaluated, adopting male fanning behavior as a key behavioral component. Also, the activity of polar and nonpolar fraction of female-body extract in hexane obtained using solid-phase extraction technique was investigated. In order to identify cuticular compounds, male and female whole-body extracts with hexane and acetone were analyzed by gas chromatography-mass spectrometry. Th…
Antagonistic effects of hypertrehalosemic neuropeptide on the activities of 6-phosphofructo-1-kinase and fructose-1,6-bisphosphatase in cockroach fat…
2001
Hypertrehalosemic neuropeptides from the corpora cardiaca such as the decapeptide Bld HrTH bring about a profound switch in the metabolic activity of cockroach fat body during which production of the blood sugar trehalose is stimulated while the catabolism of carbohydrate (glycolysis) is inhibited. The mechanisms of the metabolic switch are not fully understood. Incubation of isolated fat body from the cockroach Blaptica dubia with 10(-8) M Bld HrTH, for 10-60 min, stimulated glycogen breakdown and increased the content of the substrates of both the glycolytic enzyme 6-phosphofructo-1-kinase (PFK, EC 2.7.1.11) and the gluconeogenic enzyme fructose-1,6-bisphosphatase (FBPase, EC 3.1.3.11) in…
Vitellogenin polypeptide levels in one susceptible and one cadmium-resistant strain of Oncopeltus fasciatus (Heteroptera: Lygaeidae), and its role in…
2005
The heavy metal Cd has recently been shown to have endocrine disrupting activity in different vertebrate species. In the insect Oncopeltus fasciatus, Cd exposure delays ovarian maturation and inhibits vitellogenesis, probably through a reduction in vitellogenin (Vg) polypeptide synthesis. An O. fasciatus strain was selected in the laboratory for Cd resistance with gradually increasing Cd concentrations for 50 generations. Cd-selected (OCdR) insects were 2.7-2.3 times more resistant to chronic exposure to Cd than susceptible (OS) insects. OCdR females showed increased (up to 90%) Vg polypeptide levels in hemolymph. Vg polypeptide synthesis was equally decreased in OCdR and OS females after a…
Karyological studies in Coris julis (Pisces, Labridae).
1988
In the present investigation the diploid number 2n = 48 (NF = 58) has been determined for females, primary males, and secondary males of Coris julis from the Gulf of Palermo. Differentiated sex chromosomes have not been observed in the population under study.
Tick-borne bacteria in Ixodes ricinus collected in southern Norway evaluated by a commercial kit and established real-time PCR protocols
2015
Ticks are important vectors of human pathogens. The knowledge of disease causing agents harboured by ticks in Norway is limited. The focus of this study was (a) to detect the bacteria of medical importance in ticks collected from the vegetation at locations in the southern part of the country and (b) to evaluate a novel commercially available multiplex PCR based method by comparing results with conventional established real-time PCR protocols. Borrelia burgdorferi sensu lato was confirmed to be the most prevalent pathogen detected (31%) among one hundred individually analysed adult ticks. Borrelia miyamotoi, a spirochete associated with relapsing fever, was detected in one sample. Anaplasma…
Multiple mating by females is a natural outcome of a null model of mate encounters
2012
Why do females of so many species mate multiply? The question makes use of an implicit null model that females by default should be monandrous and that polyandry requires an explanation. Here, we make thesimplepoint that females encountermates overtheir lifetimeina stochasticmanner,andas theyshouldacceptatleastonemale,acceptanceofallmales maybea betternullmodelthanthemore advanced strategy of accepting thefirst satisfactory one and rejecting all others. The advantage of this view is that it makes it explicit that females must accept and reject mates without precise knowledge of future mate encounters. In insects, for example, limitations of cognitive and sensory capabilities make it hard fo…
Temporal patterns in immune responses to a range of microbial insults (Tenebrio molitor).
2008
8 pages; International audience; Much work has elucidated the pathways and mechanisms involved in the production of insect immune effector systems. However, the temporal nature of these responses with respect to different immune insults is less well understood. This study investigated the magnitude and temporal variation in phenoloxidase and antimicrobial activity in the mealworm beetle Tenebrio molitor in response to a number of different synthetic and real immune elicitors. We found that antimicrobial activity in haemolymph increased rapidly during the first 48h after a challenge and was maintained at high levels for at least 14 days. There was no difference in the magnitude of responses …
Protein synthesis in developing ovaries of mealworm under in vivo and in vitro conditions: Effects of diflubenzuron
1996
Abstract The effect of diflubenzuron (DFB) on protein synthesis in the ovaries of Tenebrio molitor was evaluated during oocyte maturation using in vivo and in vitro assays. When incorporated into the diet (5 and 10 mg g −1 ), DFB was found to affect both the weight, the protein levels and the incorporation of tritiated leucine into proteins of ovaries. In addition, electrophoretic separation of ovarian proteins by sodium dodecyl sulfate-polyacrylamide slab gels (SDS-PAGE) showed that DFB applied in vivo did not have a significant effect on the number of protein bands. When added to the culture medium (5 and 10 μg ml −1 ), DFB resulted in a slight but significant decrease in the rate of inco…