The insect cuticle is the interface between internal homeostasis and the often harsh external environment. Cuticular hydrocarbons (CHCs) are key constituents of this hard cuticle and are associated with a variety of functions including stress response and communication. CHC production and deposition on the insect cuticle vary among natural populations and are affected by developmental temperature; however, little is known about CHC plasticity in response to the environment experienced following eclosion, during which time the insect cuticle undergoes several crucial changes. We targeted this crucial to important phase and studied post-eclosion temperature effects on CHC profiles in two natural populations of Drosophila melanogaster. A forty-eight hour post-eclosion exposure to three different temperatures (18, 25, and 30°C) significantly affected CHCs in both ancestral African and more recently derived North American populations of D. melanogaster. A clear shift from shorter to longer CHCs chain length was observed with increasing temperature, and the effects of post-eclosion temperature varied across populations and between sexes. The quantitative differences in CHCs were associated with variation in desiccation tolerance among populations. Surprisingly, we did not detect any significant differences in water loss rate between African and North American populations. Overall, our results demonstrate strong genetic and plasticity effects in CHC profiles in response to environmental temperatures experienced at the adult stage as well as associations with desiccation tolerance, which is crucial in understanding holometabolan responses to stress.
- Keywords
- Drosophila melanogaster, cuticular hydrocarbons, desiccation tolerance, eclosion, natural populations, phenotypic plasticity, water loss rate,
- Publication type
- Journal Article MeSH
Investigations performed on adult insects revealed that putative components of the central pacemaker, the protein Period (PER) and the pigment-dispersing hormone (PDH), are immunocytochemically detectable in discrete sets of brain neurons throughout the class of Insecta, represented by a bristletail, mayfly, damselfly, 2 locust species, stonefly, 2 bug species, goldsmith beetle, caddisfly, honeybee, and 2 blowfly species. The PER-positive cells are localized in the frontal protocerebrum and in most species also in the optic lobes, which are their only location in damselfly and goldsmith beetle. Additional PER-positive cells occur in a few species either in the deuto- and tritocerebrum or in the suboesophageal ganglion. The PER staining was always confined to the cytoplasm. The PDH immunoreactivity consistently occurs in a cluster of perikarya located frontoventrally at the proximal edge of the medulla. The mayfly and both locust species possess additional PDH neurons in 2 posterior cell clusters at the proximal edge of the medulla, and mayfly, waterstrider, and 1 of the blowfly species in the central brain. PDH-positive fibers form a fanlike arrangement over the frontal side of the medulla. Two or just 1 bundle of PDH-positive fibers run from the optic lobe to the protocerebrum, with collaterals passing over to the contralateral optic lobe. Antisera to the prothoracicotropic (PTTH) and the eclosion (EH) hormones, which in some insects regulate the molting and ecdysis rhythms, respectively, typically react with a few neurons in the frontal protocerebrum. However, the PTTH-positive neurons of the mayfly and the damselfly and the EH-positive neurons of the caddisfly are located in the suboesophageal ganglion. No PTTH-like antigen was detected in locusts, and no EH-like antigens were detected in the damselfly, stonefly, locusts, and the honeybee. There are no signs of co-localization of the PER-, PDH-, PTTH-, and EH-like antigens in identical neurons.
- MeSH
- Central Nervous System metabolism MeSH
- Period Circadian Proteins MeSH
- Circadian Rhythm physiology MeSH
- Species Specificity MeSH
- Ganglia, Invertebrate metabolism MeSH
- Insecta metabolism MeSH
- Insect Hormones metabolism physiology MeSH
- Immunohistochemistry MeSH
- Nuclear Proteins metabolism physiology MeSH
- Signal Transduction MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Comparative Study MeSH
- Names of Substances
- Period Circadian Proteins MeSH
- eclosion hormone MeSH Browser
- Insect Hormones MeSH
- Nuclear Proteins MeSH
- prothoracicotropic hormone MeSH Browser
The cephalic nervous system of the firebrat contains antigens recognized by antisera to the clock protein period (PER), the prothoracicotropic hormone (PTTH) and the eclosion hormone (EH). The content of the 115 kDa PER-like antigen visualized on the western blots fluctuates in diurnal rhythm with a maximum in the night. The oscillations entrained in a 12:12 h light/dark (LD) cycle persist in the darkness and disappear in continuous light. They are detected by immunostaining in 14 pairs of the protocerebral neurons and are extreme in four suboesophageal neurons and two cells in each corpus cardiacum that contain PER only during the night phase. No circadian fluctuations occur in three lightly stained perikarya of the optic lobe. Five cell bodies located in each brain hemisphere between the deuto-and the tritocerebrum retain weak immunoreactivity under constant illumination. In all cells, the staining is confined to the cytoplasm and never occurs in the cell nuclei. The cells containing PER-like material do not react with the anti-PTTH and anti-EH antisera, which recognize antigens of about 50 and 20 kDa, respectively. The anti-PTTH antiserum stains in each brain hemisphere seven neurons in the protocerebrum, eight in the optic lobe, and 3-5 in the posterior region of the deutocerebrum. The antiserum to EH reacts in each hemisphere with just two cells located medially to the mushroom bodies. No cycling of the PTTH-like and EH-like antigens was detected.
- MeSH
- Antigens immunology MeSH
- Immune Sera MeSH
- Circadian Rhythm physiology MeSH
- Insecta metabolism MeSH
- Insect Hormones immunology metabolism MeSH
- Immunohistochemistry MeSH
- Nuclear Proteins immunology MeSH
- Brain metabolism ultrastructure MeSH
- Neurons immunology metabolism MeSH
- Light MeSH
- Darkness MeSH
- Blotting, Western MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Antigens MeSH
- Immune Sera MeSH
- eclosion hormone MeSH Browser
- Insect Hormones MeSH
- Nuclear Proteins MeSH
- prothoracicotropic hormone MeSH Browser
Azole fungicides have been essential pillars of global food security since the commercialization of triadimefon. However, the potential for fungicides to induce sublethal effects on larval development and emergence from overwintering is underresearched. We hypothesized that contact exposure to field-realistic concentrations of a broad spectrum of triazole fungicides alters the pupation and metamorphosis of crabronid wasps. Therefore, triazole fungicides shape the hymenopteran communities in agrocenoses. We applied field-realistic concentrations of three triazole fungicides, difenoconazole, penconazole, and tebuconazole, to the defecated prepupae of Pemphredon fabricii (Hymenoptera: Crabronidae). We monitored their survival, pupation, and metamorphosis into adults, including the timing of these events. All three tested triazole fungicides altered the time to the metamorphosis into adults of P. fabricii prepupae compared to the vehicle-treated controls. This effect was concentration-independent within the recommended concentration ranges for foliar applications. However, the three triazole fungicides were not associated with any significant declines in overall survival. Thus, the commonly used triazole fungicides affect the synchronization of the metamorphosis into adults with the availability of food and nesting resources of the study species. The study compounds did not affect the survival, which agrees with previous studies of other azole fungicides, which revealed effects on survival only when used in combination with other compounds. Further research should address the multiplicative effects of the triazole fungicides with other agrochemicals on the timing of the metamorphosis of bees and wasps.
- Keywords
- Eclosion, Fungicide, Hymenoptera, Pupation, Reproduction, Sublethal effect,
- MeSH
- Azoles pharmacology MeSH
- Metamorphosis, Biological MeSH
- Fungicides, Industrial * chemistry MeSH
- Hymenoptera * MeSH
- Wasps * MeSH
- Triazoles chemistry toxicity MeSH
- Bees MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Azoles MeSH
- Fungicides, Industrial * MeSH
- Triazoles MeSH
The diel rhythmicity of adult eclosion was recorded in reciprocal F1 hybrids between the wild-type (Sapporo) and mutant (NPD) strains of Chymomyza costata and the functionality of central circadian clocks was checked in both strains by assessing diel and circadian patterns of the per gene mRNA abundance oscillations in fly heads using competitive polymerase chain reaction methodology. The previously detected mutations in the per coding region of the NPD strain (Shimada, Entomol. Sci. 2 (1999) 575) were found to be primarily neither responsible for the loss of the eclosion rhythm nor for the malfunction of the circadian clocks. While distinct diel and circadian rhythms in per mRNA abundance were found in the wild-type flies, the npd-mutants showed constant (arrhythmic) and low abundance of the per mRNA transcripts. Because the non-photoperiodism, arrhythmicity of adult eclosion and the malfunction of central circadian clocks all seem to result from a mutation in the autosomal npd locus, we hypothesize, that a product coded by this locus may represent a 'point of contact' between the circadian and photoperiodic time measurement systems in C. costata.
- Publication type
- Journal Article MeSH
Homologous circadian genes are found in all insect clocks, but their contribution to species-specific circadian timing systems differs. The aim of this study was to extend research within Lepidoptera to gain a better understanding of the molecular mechanism underlying circadian clock plasticity and evolution. The Mediterranean flour moth, Ephestia kuehniella (Pyralidae), represents a phylogenetically ancestral lepidopteran species. We have identified circadian rhythms in egg hatching, adult emergence, and adult locomotor activity. Cloning full-length complementary DNAs and further characterization confirmed one copy of period and timeless genes in both sexes. Both per and tim transcripts oscillate in their abundance in E. kuehniella heads under light-dark conditions. PER-like immunoreactivity (PER-lir) was observed in nuclei and cytoplasm of most neurons in the central brain, the ventral part of subesophageal complex, the neurohemal organs, the optic lobes, and eyes. PER-lir in photoreceptor nuclei oscillated during the day with maximal intensity in the light phase of the photoperiodic regime and lack of a signal in the middle of the dark phase. Expression patterns of per and tim messenger RNAs (mRNAs) were revealed in the identical location as the PER-lir was detected. In the photoreceptors, a daily rhythm in the intensity of expression of both per mRNA and tim mRNA was found. These findings suggest E. kuehniella as a potential lepidopteran model for circadian studies.
- Keywords
- Lepidoptera, PER-like immunoreactivity, activity rhythms, circadian clock, eclosion rhythm, timeless,
- MeSH
- Biological Clocks genetics MeSH
- Circadian Clocks genetics MeSH
- Period Circadian Proteins genetics metabolism MeSH
- Circadian Rhythm genetics physiology MeSH
- Phenotype MeSH
- Photoperiod MeSH
- Insect Proteins genetics MeSH
- In Situ Hybridization MeSH
- Immunohistochemistry MeSH
- Nuclear Proteins metabolism MeSH
- Cloning, Organism MeSH
- DNA, Complementary MeSH
- RNA, Messenger genetics metabolism MeSH
- Brain metabolism MeSH
- Moths genetics growth & development physiology MeSH
- Gene Expression Regulation MeSH
- Sequence Analysis, DNA MeSH
- Light MeSH
- Optic Lobe, Nonmammalian physiology MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Period Circadian Proteins MeSH
- Insect Proteins MeSH
- Nuclear Proteins MeSH
- DNA, Complementary MeSH
- RNA, Messenger MeSH
Hoverflies (Diptera, Syrphidae) are cosmopolitan, generalist flower visitors and among the most important pollinators after bees and bumblebees. The dronefly Eristalis tenax can be found in temperate and continental climates across the globe, often synanthropically. Eristalis tenax pupae of different generations and different climate zones are thus exposed to vastly different temperatures. In many insects, the ambient temperature during the pupal stage affects development, adult size, and survival; however, the effect of developmental temperature on these traits in hoverflies is comparatively poorly understood. We here reared E. tenax pupae at different temperatures, from 10°C to 25°C, and quantified the effect on adult hoverflies. We found that pupal rearing at 17°C appeared to be optimal, with high eclosion rates, longer wings, and increased adult longevity. Rearing temperatures above or below this optimum led to decreased eclosion rates, wing size, and adult survival. Similar thermal dependence has been observed in other insects. We found that rearing temperature had no significant effect on locomotor activity, coloration or weight, despite evidence of strong sexual dimorphism for each of these traits. Our findings are important as hoverflies are key pollinators, and understanding the effects of developmental temperature could potentially be useful for horticulture.
- Keywords
- Diptera, Eristalis tenax, Syrphidae, body size, locomotor activity, morphometrics, phenotypic plasticity, rearing temperature, thermal performance,
- Publication type
- Journal Article MeSH
Vitellogenesis (yolk accumulation) begins upon eclosion and continues through the process of sexual maturation. Upon reaching sexual maturity, vitellogenesis is placed on hold until it is induced again by mating. However, the mechanisms that gate vitellogenesis in response to developmental and reproductive signals remain unclear. Here, we have identified the neuropeptide allatostatin-C (AstC)-producing neurons that gate both the initiation of vitellogenesis that occurs post-eclosion and its re-initiation post-mating. During sexual maturation, the AstC neurons receive excitatory inputs from Sex Peptide Abdominal Ganglion (SAG) neurons. In mature virgin females, high sustained activity of SAG neurons shuts off vitellogenesis via continuous activation of the AstC neurons. Upon mating, however, Sex Peptide inhibits SAG neurons, leading to deactivation of the AstC neurons. As a result, this permits both JH biosynthesis and the progression of vitellogenesis in mated females. Our work has uncovered a central neural circuit that gates the progression of oogenesis.
- MeSH
- Drosophila melanogaster physiology MeSH
- Animals, Genetically Modified MeSH
- Neurons metabolism MeSH
- Oocytes growth & development MeSH
- Drosophila Proteins genetics metabolism MeSH
- Sexual Behavior, Animal MeSH
- Somatostatin metabolism MeSH
- Vitellogenesis * MeSH
- Animals MeSH
- Check Tag
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Research Support, N.I.H., Extramural MeSH
- Names of Substances
- AstC protein, Drosophila MeSH Browser
- Drosophila Proteins MeSH
- Somatostatin MeSH
Ticks of the species Amblyomma variegatum (Fabr.), Boophilus decoloratus (Koch), Boophilus geigyi Aeschl. et Morel, and Hyalomma rufipes Koch were detached from cattle, sheep and horses and the influence of these various hosts on the biology of ticks was investigated. No A. variegatum was found in horses. The parameters studied were preoviposition and oviposition periods, ovipositional capacity, eclosion period, hatching patterns, egg sizes and temperature effect. Although the preoviposition and eclosion periods were similar in each tick species irrespective of the host from which the adults were detached, the oviposition period was longest among ticks detached from cattle and least among those detached from horses. The ticks engorged on cattle also laid the highest number of eggs and those which engorged on horses laid the least number. The hatching pattern of the eggs in any tick species was not influenced by the host from which the female was detached. The lengths of eggs of the ticks whose adults were detached from horses were generally smaller than those detached from cattle and sheep. Temperature affected the adult females detached from cattle, sheep and horses equally and this was also true of the larvae they produced. The practical field applications of these results are discussed.
- MeSH
- Host-Parasite Interactions MeSH
- Oviposition MeSH
- Ticks physiology MeSH
- Horses parasitology MeSH
- Sheep parasitology MeSH
- Ovum physiology MeSH
- Cattle parasitology MeSH
- Feeding Behavior MeSH
- Temperature MeSH
- Animals MeSH
- Check Tag
- Cattle parasitology MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Comparative Study MeSH
- Geographicals
- Nigeria MeSH
The tortoise tick Hyalomma aegyptium has a typical three-host life-cycle. Whereas its larvae and nymphs are less host-specific feeding on a variety of tetrapods, tortoises of the genus Testudo are principal hosts of adults. Ticks retained this trait also in our study under laboratory conditions, while adults were reluctant to feed on mammalian hosts. Combination of feeding larvae and nymphs on guinea pigs and feeding of adults on Testudo marginata tortoises provided the best results. Feeding period of females was on average 25 days (range 17-44), whereas males remain after female engorgement on tortoise host. Female pre-oviposition period was 14 days (3-31), followed by 24 days of oviposition (18-29). Pre-eclosion and eclosion, both together, takes 31 days (21-43). Larvae fed 5 days (3-9), then molted to nymphs after 17 days (12-23). Feeding period of nymphs lasted 7 days (5-10), engorged nymphs molted to adults after 24 days (19-26). Sex ratio of laboratory hatched H. aegyptium was nearly equal (1:1.09). The average weight of engorged female was 0.95 (0.72-1.12) g. The average number of laid eggs was 6,900 (6,524-7,532) per female, it was significantly correlated with weight of engorged female. Only 2.8% of engorged larvae and 1.8% of engorged nymphs remained un-molted and died. Despite the use of natural host species, feeding success of females reached only 45%. The whole life-cycle was completed within 147 days (98-215).
- MeSH
- Longevity MeSH
- Ixodidae growth & development physiology MeSH
- Oviposition MeSH
- Larva growth & development physiology MeSH
- Nymph growth & development physiology MeSH
- Sex Ratio MeSH
- Molting MeSH
- Feeding Behavior MeSH
- Turtles parasitology MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
