Photoperiodic regulation of reproductive diapause in two invasive and two native populations of Harmonia axyridis and in one native population of Harmonia yedoensis was investigated in laboratory at 20°C, five photoperiods (day length of 10, 12, 14, 16 and 18 h) and two diets: (i) eggs of the Angoumois grain moth Sitotroga cerealella and (ii) the green peach aphid, Myzus persicae. Laboratory strains originated from native populations of H. axyridis from Irkutsk province of Siberia and H. yedoensis from South Korea showed a strong photoperiodic response: under short photoperiods (10–14 h and 10–12 h for H. axyridis and H. yedoensis, correspondingly), all females which fed on eggs and most of those fed on aphids did not start to lay eggs during 40 days after emergence, while under long photoperiods, all females fed on aphids and most of those fed on eggs oviposited. The photoperiodic response of H. axyridis from South Korea was less strong: on the both diets, the range of the photoperiodic response (the difference in the proportion of ovipositing females between the treatments with long and short days) was ca 40%. In the European (Czech Republic) and in the Caucasian (Sochi region, Russia) invasive populations of H. axyridis, the photoperiodic response was very weak: the proportion of females that started oviposition (when fed on aphids) or at least reproductive maturation (when fed on eggs) during 40 days after emergence was close to 100%, independently of the photoperiodic conditions. Obviously, instead of a rapid micro‐evolutionary adaptation of the critical day length to a new climate, the invasive populations of the harlequin ladybird decrease their dependence on photoperiod and thus the weak photoperiodic response of SE Asian population of H. axyridis can be considered as a pre‐adaptation further developed during the invasion. 相似文献
The Neotropical‐native figitid Aganaspis pelleranoi (Brèthes) and the Asian braconid Diachasmimorpha longicaudata (Ashmead) are two parasitoids of Tephritidae fruit flies with long and recent, respectively, evolutionary histories in the Neotropics. Both species experienced a recent range of overlap. In Argentina, A. pelleranoi is a potential species in biological control programs against the pestiferous tephritid species, Anastrepha fraterculus (Wiedemann) and Ceratitis capitata (Wiedemann), whereas D. longicaudata is already used in open‐field releases against Medfly in central‐western Argentina. To characterize the host‐foraging strategies of A. pelleranoi and D. longicaudata, olfactometer experiments were conducted comparing responses to C. capitata and A. fraterculus larvae, in two kinds of food substrate: fruit and artificial larval medium. To control the possible influence of host larvae used for parasitoid rearing on olfactory response, two strains of both parasitoid species, reared on both tephrtid species, were studied. Volatiles directly emanating either from A. fraterculus or C. capitata larvae may be detected by both A. pelleranoi and D. longicaudata, although chemical stimuli originating from the combination of host larvae and the habitat of the host were preferred. However, olfactory cues associated with host larvae probably play a relevant role in host searching behaviour of A. pelleranoi, whereas for D. longicaudata, the host‐habitat olfactory stimuli would be highly essential in short‐range host location. The strain of the parasitoids did not affect host search ability on the two tephritid species evaluated. These evidences are relevant for mass production of both parasitoids and their impact following open‐field augmentative releases. 相似文献
The box‐tree moth Cydalima perspectalis (Walker) is an invasive pest causing severe damage to box trees (Buxus spp.). It is native to Japan, Korea and China, but established populations have been recorded in a number of locations across Europe since 2007 and the spread of the insect continues. The developmental investigations suggest that larvae overwinter mainly in their 3rd instar in Europe and that diapause is induced by a day length of about 13.5 h. One and a half to 2 months in the cold are necessary to terminate diapause. Threshold temperatures for development and number of degree‐days to complete a generation are slightly different from those calculated in previous studies in Japan. A bioclimatic (CLIMEX®) model for C. perspectalis in Europe was developed, based on climate, ecological and developmental parameters from the literature and new field and laboratory studies on diapause termination, thermal requirements and phenology. The model was then validated with actual distribution records and phenology data. The current distribution and life history of C. perspectalis in Europe were consistent with the predicted distribution. The climate model suggests that C. perspectalis is likely to continue its spread across Europe, except for Northern Fenno‐Scandinavia, Northern Scotland and high mountain regions. The northern distribution of C. perspectalis is expected to be limited by a number of degree‐days above the temperature threshold insufficient to complete a generation, whereas its southern range is limited by the absence of a cold period necessary to resume diapause. The model predicts relatively high Ecoclimatic Indices throughout most of Europe, suggesting that the insect has the potential of becoming a pest in most of its predicted range. However, damage is likely to be higher in Southern and Central Europe where the moth is able to complete at least two generations per year. 相似文献
As dead wood is ephemeral, saproxylic insect species must be able to effectively locate new resources via, e.g. olfactory cues.
Although saproxylic flat bugs feed on fungal mycelia, published evidence points to their use of dead wood‐specific volatile cues rather than fungal‐specific cues for long‐distance orientation towards new habitat patches.
To evaluate which olfactory cues saproxylic flat bugs use for short‐distance orientation, we tested the attraction of Aradus obtectus (Vasarhelyi) to fresh wood, fungal mycelia and fungal fruiting bodies using an olfactometer.
Aradus obtectus individuals were attracted only to fungal mycelia but not to wood or fungal fruiting bodies.
Our results and those of our earlier field experiment testing long‐distance attraction (Seibold et al., 2014 ) together suggest that A. obtectus uses cues emitted by dead wood to locate potential resources over long distances, but relies on olfactory cues emitted by mycelia of its host species to locate suitable short‐range microhabitats.
Different strains of Nile tilapia can be found worldwide. To successfully use them in breeding programs, they must be genetically characterized. In this study, four strains of Nile tilapia – UFLA, GIFT, Chitralada and Red‐Stirling – were genetically characterized using 10 noncoding microsatellite loci and two microsatellites located in the promoter and first intron of the growth hormone gene (GH). The two microsatellites in the GH gene were identified at positions ?693 to ?679 in the promoter [motif (ATTCT)8] and in intron 1 at positions +140 to +168 [motif (CTGT)7]. Genetic diversity was measured as mean numbers of alleles and expected heterozygosity, which were 4 and 0.60 (GIFT), 3.5 and 0.71 (UFLA), 4.5 and 0.57 (Chitralada) and 2.5 and 0.42 (Red‐Stirling) respectively. Genetic differentiation was estimated both separately and in combination for noncoding and GH microsatellites markers using Jost's DEST index. The UFLA and GIFT strains were the least genetically divergent (DEST = 0.10), and Chitralada and Red‐Stirling were the most (DEST = 0.58). The UFLA strain was genetically characterized for the first time and, because of its unique origin and genetic distinctness, may prove to be an important resource for genetic improvement of Nile tilapia. This study shows that polymorphisms found in coding gene regions might be useful for assessing genetic differentiation among strains. 相似文献
Observed changes in mean temperature and increased frequency of extreme climate events have already impacted the distributions and phenologies of various organisms, including insects. Although some research has examined how parasitoids will respond to colder temperatures or experimental warming, we know relatively little about how increased variation in temperature and humidity could affect interactions between parasitoids and their hosts. Using a study system consisting of emerald ash borer (EAB), Agrilus planipennis, and its egg parasitoid Oobius agrili, we conducted environmentally controlled laboratory experiments to investigate how increased seasonal climate variation affected the synchrony of host–parasitoid interactions. We hypothesized that increased climate variation would lead to decreases in host and parasitoid survival, host fecundity, and percent parasitism (independent of host density), while also influencing percent diapause in parasitoids. EAB was reared in environmental chambers under four climate variation treatments (standard deviations in temperature of 1.24, 3.00, 3.60, and 4.79°C), while O. agrili experiments were conducted in the same environmental chambers using a 4 × 3 design (four climate variation treatments × 3 EAB egg densities). We found that EAB fecundity was negatively associated with temperature variation and that temperature variation altered the temporal egg laying distribution of EAB. Additionally, even moderate increases in temperature variation affected parasitoid emergence times, while decreasing percent parasitism and survival. Furthermore, percent diapause in parasitoids was positively associated with humidity variation. Our findings indicate that relatively small changes in the frequency and severity of extreme climate events have the potential to phenologically isolate emerging parasitoids from host eggs, which in the absence of alternative hosts could lead to localized extinctions. More broadly, these results indicate how climate change could affect various life history parameters in insects, and have implications for consumer–resource stability and biological control. 相似文献
Sex‐ and age‐related differences in cognitive abilities are frequently reported. However, the sex‐ and age‐related differences in dog olfaction due to biological system are still poorly understood. We examined c‐fos expression in dog olfactory bulbs by immunohistochemistry approaches. The c‐fos is mainly expressed in the olfactory glomerular layer (GL), mitral cell layer (ML) and granule cell layer (GRL). We found that a higher density of c‐fos‐positive cells could be detected in the ML of olfactory bulbs of adult female dogs compared with that in males and the c‐fos‐positive cells in females' olfactory bulbs are more distinct. Sex‐related differences in c‐fos expression also appeared in the GL of olfactory bulbs in juvenile dogs. We also discovered that the density of c‐fos‐positive cells in the GRL of adult dogs was much higher than that in the GRL of juvenile dogs. Our results indicate that cells in the olfactory bulbs of female dogs are more active than those in males and female dogs may have much stronger ability for long‐time memory of odours than male dogs. Furthermore, our results also suggest that adult dogs may have much stronger ability for long‐time memory of odours and can deal with more complicated odour information than juvenile dogs. 相似文献
Members of the ADAM (a disintegrin and metalloprotease) family are type I transmembrane proteins involved in biological processes of proteolysis, cell adhesion, cell–matrix interaction, as well as in the intracellular signaling transduction. In the present study, expression patterns of seven members of the ADAM family were investigated at the early stages of the developing cochlea by in situ hybridization. The results show that each individual ADAM is expressed and regulated in the early developing cochlea. ADAM9, ADAM10, ADAM17, and ADAM23 are initially and widely expressed in the otic vesicle at embryonic day 2.5 (E2.5) and in the differential elements of the cochlear duct at E9, while ADAM12 is expressed in acoustic ganglion cells at E7. ADAM22 is detectable in cochlear ganglion cells as early as from E4 and in the basilar papilla from E7. Therefore, the present study extends our previous results and suggests that ADAMs also play a role in the early cochlear development. 相似文献
In seasonal environments, organisms synchronize their life cycle with the annual cycle of environmental factors. In many insect species, this includes a diapause response: a timed dormant stage that allows to survive harsh winter conditions. Previously, we have shown that larval diapause in the parasitic wasp Nasonia vitripennis is induced by the mother upon exposure to a threshold number of short photoperiods (named switch point) and diapause response follows a latitudinal cline in natural populations. Here, we present a QTL analysis using two lines derived from the extremes of this clinal distribution: a northern line from Oulu, Finland and a southern line from Corsica, France. A genomic region on chromosome 1 and one on chromosome 5 were found to be associated with photoperiodic diapause induction. Interestingly, these regions contain the putative clock genes period, cycle (chromosome 1) and cryptochrome (chromosome 5). An analysis of period polymorphisms in seven European populations showed a clinal distribution of two main haplotypes that correlate with the latitudinal cline for diapause induction. 相似文献
For aquatic and riparian plants, the important role of fish in seed dispersal is increasingly recognised. While the propensity of seeds to disperse is known to be a function of morphological, physical and chemical traits of the seed, in the case of fish‐mediated seed dispersal (ichthyochory), it is largely unknown how seed traits modulate the potential for seed ingestion and their subsequent survival through the gut. Furthermore, which seed traits are important may vary among fish species.
To evaluate the role of both seed and fish traits in ichthyochory, we fed seeds of 19 aquatic and riparian plant species to fish with differing feeding mechanisms. Cyprinus carpio (common carp) has a pharyngeal ‘mill’, which it uses physically to crush hard food, while Oreochromis mossambicus (Mozambique tilapia) has only tiny oral and pharyngeal teeth and instead relies more on chemical digestion.
A number of seed traits, including hardness, size and shape, were important determinants of the potential of seeds for ichthyochory. Certain traits (e.g. seed dimensions) were more important during ingestion, whereas other traits were more important for seed survival and subsequent germination (e.g. seed hardness, mucilaginous coat). Compared to controls, germination of retrieved seeds in carp was lower in 10 and higher in two plant species, whereas for tilapia, it was lower in seven and higher in three species. Overlap between these plant species was low, indicating clear difference between the fish studied in their potential for seed dispersal. Carp increased in size during the experiment and concomitant decreases in seed survival and retrieval were found, suggesting that body size and the correlated bite force is an important fish trait in ichthyochory.
Overall, seed hardness, size and shape appear crucial for the survival of seeds passing through the guts of carp and tilapia. Beyond this general pattern, a greater complexity of trait‐performance relationships appeared: different seed traits are involved during each of the stages of ichthyochory. Moreover, the importance of seed traits differed between carp and tilapia, with some traits having interactive and contrasting effects in both fish species. Aquatic plants with floating seeds adapted to hydrochorous dispersal were less likely to be dispersed by tilapia than plants with non‐floating seeds, suggesting a dispersal trade‐off between ichthyochory and hydrochory. Thus, depending on their seed characteristics, fish may offer an additional dispersal route to aquatic and riparian plants.
In flowering plants, cell–cell communication plays a key role in reproductive success, as both pollination and fertilization require pathways that regulate interactions between many different cell types. Some of the most critical of these interactions are those between the pollen tube (PT) and the embryo sac, which ensure the delivery of sperm cells required for double fertilization. Synergid cells function to attract the PT through secretion of small peptides and in PT reception via membrane‐bound proteins associated with the endomembrane system and the cell surface. While many synergid‐expressed components regulating PT attraction and reception have been identified, few tools exist to study the localization of membrane‐bound proteins and the components of the endomembrane system in this cell type. In this study, we describe the localization and distribution of seven fluorescent markers that labelled components of the secretory pathway in synergid cells of Arabidopsis thaliana. These markers were used in co‐localization experiments to investigate the subcellular distribution of the two PT reception components LORELEI, a GPI‐anchored surface protein, and NORTIA, a MILDEW RESISTANCE LOCUS O protein, both found within the endomembrane system of the synergid cell. These secretory markers are useful tools for both reproductive and cell biologists, enabling the analysis of membrane‐associated trafficking within a haploid cell actively involved in polar transport. 相似文献
In this study, we have evaluated cerebral atrophy, neurometabolite homeostasis, and neural energetics in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridin (MPTP) model of Parkinson's disease. In addition, the efficacy of acute l ‐DOPA treatment for the reversal of altered metabolic functions was also evaluated. Cerebral atrophy and neurochemical profile were monitored in vivo using MRI and 1H MR Spectroscopy. Cerebral energetics was studied by 1H‐[13C]‐NMR spectroscopy in conjunction with infusion of 13C labeled [1,6‐13C2]glucose or [2‐13C]acetate. MPTP treatment led to reduction in paw grip strength and increased level of GABA and myo‐inositol in striatum and olfactory bulb. 13C Labeling of glutamate‐C4 (1.93 ± 0.24 vs. 1.48 ± 0.06 μmol/g), GABA‐C2 (0.24 ± 0.04 vs. 0.18 ± 0.02 μmol/g) and glutamaine‐C4 (0.26 ± 0.04 vs. 0.20 ± 0.04 μmol/g) from [1,6‐13C2]glucose was found to be decreased with MPTP exposure in striatum as well as in other brain regions. However, glutamine‐C4 labeling from [2‐13C]acetate was found to be increased in the striatum of the MPTP‐treated mice. Acute l ‐DOPA treatment failed to normalize the increased ventricular size and level of metabolites but recovered the paw grip strength and 13C labeling of amino acids from [1,6‐13C2]glucose and [2‐13C]acetate in MPTP‐treated mice. These data indicate that brain energy metabolism is impaired in Parkinson's disease and acute l ‐DOPA therapy could temporarily recover the cerebral metabolism.
Few studies report on the in vivo requirement for hematopoietic niche factors in the mammalian embryo. Here, we comprehensively analyze the requirement for Kit ligand (Kitl) in the yolk sac and aorta–gonad–mesonephros (AGM) niche. In‐depth analysis of loss‐of‐function and transgenic reporter mouse models show that Kitl‐deficient embryos harbor decreased numbers of yolk sac erythro‐myeloid progenitor (EMP) cells, resulting from a proliferation defect following their initial emergence. This EMP defect causes a dramatic decrease in fetal liver erythroid cells prior to the onset of hematopoietic stem cell (HSC)‐derived erythropoiesis, and a reduction in tissue‐resident macrophages. Pre‐HSCs in the AGM require Kitl for survival and maturation, but not proliferation. Although Kitl is expressed widely in all embryonic hematopoietic niches, conditional deletion in endothelial cells recapitulates germline loss‐of‐function phenotypes in AGM and yolk sac, with phenotypic HSCs but not EMPs remaining dependent on endothelial Kitl upon migration to the fetal liver. In conclusion, our data establish Kitl as a critical regulator in the in vivoAGM and yolk sac endothelial niche. 相似文献
During pregnancy, up‐regulation of heparin‐binding (HB‐) EGF and cyclooxygenase‐2 (COX‐2) in the uterine epithelium contributes to decidualization, a series of uterine morphological changes required for placental formation and fetal development. Here, we report a key role for the lipid mediator lysophosphatidic acid (LPA) in decidualization, acting through its G‐protein‐coupled receptor LPA3 in the uterine epithelium. Knockout of Lpar3 or inhibition of the LPA‐producing enzyme autotaxin (ATX) in pregnant mice leads to HB‐EGF and COX‐2 down‐regulation near embryos and attenuates decidual reactions. Conversely, selective pharmacological activation of LPA3 induces decidualization via up‐regulation of HB‐EGF and COX‐2. ATX and its substrate lysophosphatidylcholine can be detected in the uterine epithelium and in pre‐implantation‐stage embryos, respectively. Our results indicate that ATX–LPA–LPA3 signaling at the embryo‐epithelial boundary induces decidualization via the canonical HB‐EGF and COX‐2 pathways. 相似文献
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