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1.
An Acad Bras Cienc ; 92(1): e20181093, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236298

RESUMO

Larvae of Psychodidae develop in a variety of breeding sites, including vertebrate feces. As searching for the larvae can be an extremely difficult task, immatures of many species are little known, with descriptions of coprophagous moth flies all from outside the Neotropics. In an attempt to mitigate this challenge, we tested an oviposition trap using cattle dung as attractant, measured the efficiency and specificity of the traps and the most efficient period of exposition in the field. With 60 traps installed in one fragment of ombrophilous forest, 344 immatures were collected, distributed in four species of Psychoda and one of Feuerborniella. Psychodidae accounted for 75% of the collected Diptera. The high specificity of the trap to Psychodidae contrasts with other studies on coprophagous fauna where they appear in low abundance. Based on the metrics in this study, the most efficient period of trapping exposition was between five to eight days, but the difference was not significant probably due to the high number of zero observations among the traps. Many questions pertaining to coprophagous moth flies remain unanswered. Further research is needed to improve trapping efficiency, elucidate the effects of attractants and determine how environmental factors influence the attractiveness of bait.


Assuntos
Controle de Insetos/instrumentação , Oviposição , Psychodidae/fisiologia , Animais , Bovinos , Fezes , Feminino , Psychodidae/classificação
2.
An Acad Bras Cienc ; 92(1): e20180230, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32267303

RESUMO

The present study aimed to investigate the consequences of dietary levels of crude protein (CP) and total sulfur amino acids (TSAA, Met+Cys) on productive performance, egg quality and egg components for Lohmann Brown laying hens through 18-34 weeks of age. A 2×3 factorial design experiment was conducted using two levels of CP (16 and 18 %) and three levels of Met+ Cys (0.67, 0.72 and 0.77 %). A total of 144 Lohmann Brown laying hens at 18 weeks of age were randomly divided into 6 treatment groups. The best values of final body weight and body weight change were recorded by the hens fed 18 % CP diet. Increasing dietary CP up to 18 % accompanied with the best (P> 0.01) feed conversion, egg weight and egg mass. The combination between low-CP diet (16 %) and 0.72 % Met+ Cys gave the best percentage of egg production. The majority of egg quality traits were not significantly altered by dietary treatments. The interaction between CP and Met+Cys levels had a statistical (P>0.01) impact on egg content of moisture and total solids only. It could be concluded that the best production criteria could be obtained by using 0.72% Met+Cys. Moreover, dietary level of 16 or 18 % CP with 0.72% Met+Cys is recommended for feeding Lohmann hens.


Assuntos
Aminoácidos Sulfúricos/administração & dosagem , Ração Animal , Galinhas/fisiologia , Dieta com Restrição de Proteínas , Ovos/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Feminino , Oviposição , Ganho de Peso
3.
Pestic Biochem Physiol ; 164: 7-13, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32284139

RESUMO

Insect gustatory system plays important roles in multiple behaviors including feeding, mating, and oviposition. Gustatory receptors (GRs), located on the dendritic membrane of gustatory sensory neurons (GSNs), are crucial in peripheral coding of non-volatile compounds. However, GRs and their detailed functions remain poorly understood in lepidopteran pests. In the present work, focusing on GR genes of Plutella xylostella, an important worldwide crop pest, we cloned a candidate fructose GR gene that has two spliced variants (PxylGR43a-1 and PxylGR43a-2), and determined the tissue expression profiles by semi-quantitative reverse transcription PCR (RT-PCR). It revealed that both GR variants were highly expressed in antennae and less highly in heads of adults, while PxylGR43a-2 was also weakly expressed in other tested tissues. Functional analyses were further conducted using the Xenopus oocyte system. PxylGR43a-1 and PxylGR43a-2 both responded specifically to the d-fructose among the 12 tested sugar compounds, but PxylGR43a-2 showed much higher current response than PxylGR43a-1. In addition, the proboscis extension reflex (PER) assay was conducted, demonstrating that female moths could respond to d-fructose following stimulation of antenna. Taken together, our study contributes to elucidation of the molecular mechanisms of fructose reception and provides a potential target for development of GR based pest control techniques.


Assuntos
Proteínas de Drosophila , Mariposas , Animais , Feminino , Frutose , Oviposição
4.
Nat Rev Neurosci ; 21(5): 244-245, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32221471
5.
Ecotoxicology ; 29(4): 407-416, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32193759

RESUMO

The chive maggot, Bradysia odoriphaga (Yang and Zhang) is an economically important insect pest, affecting many key vegetables, including Chinese chive, especially in northern China. Chlorfenapyr, a halogenated pyrrole insecticide that interferes with mitochondrial oxidative phosphorylation is widely used against B. odoriphaga. In this study, we evaluated selection-induced resistance to chlorfenapyr and fitness costs in B. odoriphaga. The results showed that B. odoriphaga developed 43.32-fold resistance after continuous exposure to chlorfenapyr for over 10 consecutive generations. The life-history traits of chlorfenapyr-resistant and susceptible strains were compared using age-stage, two-sex life table approach. No significant effects were observed on the longevity and pre-adult period. However, reduction in the total pre-oviposition period (TPOP) and fecundity (eggs/female) were observed in the resistant strain. Moreover, the demographic parameters such as intrinsic rate of increase (r), net reproductive rate (R0) and finite rate of increase (λ) were also decreased significantly in the resistant strain compared to the susceptible strain. These results showed the potential of B. odoriphaga to develop resistance against chlorfenapyr under continuous selection pressure. Furthermore, there was a fitness cost linked with chlorfenapyr resistance in B. odoriphaga. We conclude that a better knowlegde on the trade-off at play between resistance degree and fitness cost could be crucial for developing further management of B. odoriphaga in China.


Assuntos
Dípteros/fisiologia , Inseticidas/toxicidade , Piretrinas/toxicidade , Animais , Feminino , Fertilidade/efeitos dos fármacos , Resistência a Inseticidas , Masculino , Oviposição/efeitos dos fármacos , Reprodução/efeitos dos fármacos
6.
Nature ; 579(7797): 101-105, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32103180

RESUMO

Mating and egg laying are tightly cooordinated events in the reproductive life of all oviparous females. Oviposition is typically rare in virgin females but is initiated after copulation. Here we identify the neural circuitry that links egg laying to mating status in Drosophila melanogaster. Activation of female-specific oviposition descending neurons (oviDNs) is necessary and sufficient for egg laying, and is equally potent in virgin and mated females. After mating, sex peptide-a protein from the male seminal fluid-triggers many behavioural and physiological changes in the female, including the onset of egg laying1. Sex peptide is detected by sensory neurons in the uterus2-4, and silences these neurons and their postsynaptic ascending neurons in the abdominal ganglion5. We show that these abdominal ganglion neurons directly activate the female-specific pC1 neurons. GABAergic (γ-aminobutyric-acid-releasing) oviposition inhibitory neurons (oviINs) mediate feed-forward inhibition from pC1 neurons to both oviDNs and their major excitatory input, the oviposition excitatory neurons (oviENs). By attenuating the abdominal ganglion inputs to pC1 neurons and oviINs, sex peptide disinhibits oviDNs to enable egg laying after mating. This circuitry thus coordinates the two key events in female reproduction: mating and egg laying.


Assuntos
Copulação/fisiologia , Drosophila melanogaster/fisiologia , Vias Neurais/fisiologia , Oviposição/fisiologia , Animais , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Feminino , Gânglios Simpáticos/citologia , Masculino , Peptídeos/metabolismo , Células Receptoras Sensoriais/metabolismo , Abstinência Sexual/fisiologia
7.
PLoS One ; 15(2): e0228880, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32040535

RESUMO

Despite its high ecological importance, the commensal interactions at community level are poorly studied. In tropical dry forests (TDF) there is a great diversity of species adapted to the high seasonality that characterizes them; however, little is known regarding how the spatial and temporal availability of resources generates changes in the pattern of commensal interactions. We experimentally studied changes in the diversity, composition, and pattern of interactions in spatio-temporal associations between the saproxylophagous beetles and their host trees in a TDF in Morelos, Mexico. A total of 65 host tree species were selected, from which 16 wood sections were obtained per species. These sections were exposed in the field to allow oviposition by the cerambycids under four different (spatio-temporal) treatments. We analyzed the network structure and generated indices at species level (i.e., specialization, species strength, and effective partners) and those related to physical characteristics of the wood (hardness and degradation rate) and the cerambycids (body size). In total, 1,323 individuals of 57 species of cerambycids emerged. Our results showed that, independently of the space and time, the network presented a nested and modular structure, with a high specialization degree and a high turnover of cerambycid species and their interactions. In general, we found that the cerambycids are mostly associated with softwood species with a lower decomposition rate of wood, as well as with the most abundant host species. The commensalistic interactions between the cerambycids and their host trees are highly specialized but are not spatio-temporally static. The high turnover in the interactions is caused by the emergence patterns of cerambycids, which seem to restrict their use to certain species. The knowledge of the spatio-temporal variation in Cerambycidae-host tree interactions allows us to predict how environmental and structural changes in the habitat can modify the species ensemble, and therefore its interactions.


Assuntos
Besouros/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Árvores/parasitologia , Animais , Biodiversidade , Besouros/patogenicidade , Ecossistema , Feminino , Florestas , Especificidade de Hospedeiro , México , Oviposição , Análise Espaço-Temporal , Simbiose/fisiologia , Clima Tropical , Madeira
8.
Exp Appl Acarol ; 80(3): 409-422, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32030606

RESUMO

Because predators may interfere with each other, an important step towards the implementation of successful release of multiple predators in biocontrol programs requires resolving how predators respond to the presence of heterospecific competitors. Several species of predatory mites are important biocontrol agents and the species Phytoseiulus macropilis and Neoseiulus californicus are used to control the two-spotted spider mite, Tetranychus urticae, an important pest in agriculture worldwide. We investigated their compatibility showing that the two predators do not avoid plants on which the other species is present together with their common prey, and demonstrated that their oviposition rates are not affected by the presence of the other species. However, the distribution of the eggs on leaf discs was affected by the presence of the heterospecific predator. This behaviour might weaken possible interference between these two biocontrol agents, which, in turn, may enable their persistence on plants and favour pest suppression. The increased joint use of several natural enemies for biological control highlights the importance of studies on predator-predator interactions.


Assuntos
Agentes de Controle Biológico , Ácaros/fisiologia , Controle Biológico de Vetores , Comportamento Predatório , Tetranychidae/patogenicidade , Animais , Feminino , Oviposição , Folhas de Planta
9.
Arch Insect Biochem Physiol ; 103(4): e21655, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31953886

RESUMO

Some studies have highlighted benefits for Lobesia botrana by adding Botrytis cinerea mycelium to an artificial larval diet and have suggested a mutualistic relationship between the two organisms on grapevine, hypothesizing that fungal sterols were the nutritional factor involved. Because the nutritional quality of an artificial diet should be similar to grapes to allow extrapolation of the results to the field conditions, in the current study L. botrana larval performance was compared when larvae were fed on grapes (berries) or two artificial diets either with or without enrichment with B. cinerea. Based on sterol analysis, the two artificial diets had high cholesterol content, but relative to berries showed comparable and low phytosterol contents, respectively (high- and low-phytosterol, HPh, and LPh). While larval fitness on the HPh diet was similar to berries, the LPh diet led to higher mortality and worse larval performance. The addition of the fungus compensated for the shortage in the LPh diet but did not improve the HPh diet. Supplementing the LPh diet with linoleic acid, which is supplied also from B. cinerea, partially improved larval performance. In a field experiment, females did not show any egg-laying preferences towards naturally botrytized bunches. The positive effect of B. cinerea on the moth's next generation that is reported in the literature could be a consequence of fungus developed inside berry tunnels bored by larvae. Therefore, based on our data and previous reports the existence of a mutualistic relationship between L. botrana and B. cinerea is not well-founded.


Assuntos
Botrytis/fisiologia , Mariposas/microbiologia , Mariposas/fisiologia , Simbiose , Ração Animal/análise , Animais , Dieta , Larva/crescimento & desenvolvimento , Larva/microbiologia , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Oviposição , Vitis
10.
PLoS One ; 15(1): e0227685, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31935250

RESUMO

The acyl-CoA-binding proteins (ACBP) act by regulating the availability of acyl-CoA in the cytoplasm and must have essential functions in lipid metabolism. The genome of the kissing-bug Rhodnius prolixus encodes five proteins of this family, but little is known about them. In this study we investigated the expression and function of RpACBP-5. Feeding induced RpACBP-5 gene expression in the posterior midgut, and an increase of about four times was observed two days after the blood meal. However, the amount of protein, which was only detected in this organ, did not change during digestion. The RpACBP-5 gene was also highly expressed in pre-vitellogenic and vitellogenic oocytes. Recombinant RpACBP-5 was shown to bind to acyl-CoA of different lengths, and it exhibited nanomolar affinity to lauroyl-CoA in an isothermal titration assay, indicating that RpACBP-5 is a functional ACBP. RpACBP-5 knockdown by RNA interference did not affect digestion, egg laying and hatching, survival, or accumulation of triacylglycerol in the fat body and oocytes. Similarly, double knockdown of RpACBP-1 and RpACBP-5 did not alter egg laying and hatching, survival, accumulation of triacylglycerol in the fat body and oocytes, or the neutral lipid composition of the posterior midgut or hemolymph. These results show that RpACBP-5 is a functional ACBP but indicate that the lack of a detectable phenotype in the knockdown insects may be a consequence of functional overlap of the proteins of the ACBP family found in the insect.


Assuntos
Inibidor da Ligação a Diazepam/genética , Inibidor da Ligação a Diazepam/metabolismo , Rhodnius/genética , Acil Coenzima A/metabolismo , Animais , Proteínas de Transporte/metabolismo , Corpo Adiposo/metabolismo , Expressão Gênica/genética , Regulação da Expressão Gênica/genética , Hemolinfa/metabolismo , Proteínas de Insetos/genética , Metabolismo dos Lipídeos/genética , Oócitos/metabolismo , Oviposição , Interferência de RNA/fisiologia , Rhodnius/metabolismo , Triglicerídeos/metabolismo
11.
J Insect Sci ; 20(1)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31927595

RESUMO

Bactrocera dorsalis (Hendel) is a notorious insect pest that attacks diverse vegetables and fruits worldwide. The sterile insect technique has been developed as an environmentally friendly and effective control method that depends on the mass production of target flies. Because dietary yeast (protein) and sucrose (carbohydrate) are important in adult diets, yeast:sucrose (Y:S) mixtures are crucial for the mass-rearing of B. dorsalis. In this study, we found adult diets with different ratios of yeast to sucrose-influenced fecundity, and an extremely high or low Y:S ratios significantly decreased egg production of B. dorsalis. Additionally, the maximum oviposition efficiency was realized at dietary yeast to sucrose ratios of 1:1 and 1:3, suggesting their potential use to produce more eggs for the mass production of B. dorsalis. Here, new gel diets having different yeast concentrations (g/L water) were also assessed for rearing B. dorsalis larvae. Gel diets containing 20 g/L yeast led to a higher pupation, pupal weight and adult eclosion rate, and a shorter developmental time than other yeast concentrations. Moreover, the present gel diet also resulted in greater pupal production and adult emergence rates than previously used liquid and solid artificial diets, revealing that it is suitable for rearing B. dorsalis larvae. This research provides a useful reference on artificial diets mixtures for mass rearing B. dorsalis, which is critical for employing the sterile insect technique.


Assuntos
Ração Animal/análise , Criação de Animais Domésticos/métodos , Oviposição , Tephritidae/fisiologia , Animais , Dieta , Feminino , Fertilidade/efeitos dos fármacos , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/fisiologia , Masculino , Oviposição/efeitos dos fármacos , Pupa/efeitos dos fármacos , Pupa/crescimento & desenvolvimento , Pupa/fisiologia , Sacarose/administração & dosagem , Tephritidae/efeitos dos fármacos , Tephritidae/crescimento & desenvolvimento , Fermento Seco/administração & dosagem
12.
Oecologia ; 192(2): 463-475, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31932923

RESUMO

The preference-performance hypothesis (PPH) states that herbivorous female insects prefer to oviposit on those host plants that are best for their offspring. Yet, past attempts to show the adaptiveness of host selection decisions by herbivores often failed. Here, we tested the PPH by including often neglected oviposition-induced plant responses, and how they may affect both egg survival and larval weight. We used seven Brassicaceae species of which most are common hosts of two cabbage white butterfly species, the solitary Pieris rapae and gregarious P. brassicae. Brassicaceous species can respond to Pieris eggs with leaf necrosis, which can lower egg survival. Moreover, plant-mediated responses to eggs can affect larval performance. We show a positive correlation between P. brassicae preference and performance only when including the egg phase: 7-day-old caterpillars gained higher weight on those plant species which had received most eggs. Pieris eggs frequently induced necrosis in the tested plant species. Survival of clustered P. brassicae eggs was unaffected by the necrosis in most tested species and no relationship between P. brassicae egg survival and oviposition preference was found. Pieris rapae preferred to oviposit on plant species most frequently expressing necrosis although egg survival was lower on those plants. In contrast to the lower egg survival on plants expressing necrosis, larval biomass on these plants was higher than on plants without a necrosis. We conclude that egg survival is not a crucial factor for oviposition choices but rather egg-mediated responses affecting larval performance explained the preference-performance relationship of the two butterfly species.


Assuntos
Brassica , Borboletas , Animais , Feminino , Herbivoria , Larva , Oviposição
13.
Oecologia ; 192(2): 375-389, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31938883

RESUMO

Amongst oviparous animals, the spatial distribution of individuals is often set initially by where females lay eggs, with potential implications for populations and species coexistence. Do the spatial arrangements of oviposition sites or female behaviours determine spatial patterns of eggs? The consequences of spatial patterns may be context independent if strong behaviours drive patterns; context dependent if the local environment dominates. We tested these ideas using a guild of stream-dwelling caddisflies that oviposit on emergent rocks, focussing on genera with contrasting behaviours. In naturally occurring oviposition landscapes (riffles with emergent rocks), we surveyed the spatial arrangement and environmental characteristics of all emergent rocks, identified and enumerated egg masses on each. Multiple riffles were surveyed to test for spatially invariant patterns and behaviours. In landscapes, we tested for spatial clumping of oviposition sites exploited by each species and for segregation of congeneric species. At oviposition sites, we characterised the frequency distributions of egg masses and tested for species associations. Genus-specific behaviours produced different spatial patterns of egg masses in the same landscapes. Congregative behaviour of Ulmerochorema spp. at landscape scales and an aggregative response at preferred oviposition sites led to clumped patterns, local aggregation and species overlap. In contrast, avoidance behaviours by congeners of Apsilochorema resulted in no or weak clumping, and species segregation in some landscapes. Spatial patterns were consistent across riffles that varied in area and oviposition site density. These results suggest that quite different oviposition behaviours may be context independent, and the consequences of spatial patterns may be spatially invariant also.


Assuntos
Insetos , Oviposição , Animais , Ovos , Feminino , Rios
14.
Insect Sci ; 27(2): 361-374, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30298557

RESUMO

Diet quality influences organismal fitness within and across generations. For herbivorous insects, the transgenerational effects of diet remain relatively underexplored. Using a 3 × 3 × 2 factorial experiment, we evaluated how N enrichment in parental diets of Neolema abbreviata (Larcordaire) (Coleoptera: Chrysomelidae), a biological control agent for Tradescantia fluminensis Vell. (Commelinaceae), may influence life history and performance of F1 and F2 offspring under reciprocal experiments. We found limited transgenerational effects of foliar nitrogen variability among life-history traits in both larvae and adults. Larval weight gain and mortality were responsive to parental diet contrary to feeding damage, pupal weight and duration taken to pupate. There were significant parental diet × test interactions in larval feeding damage, weight gain, pupal weight and time to pupation. Generally, offspring from parents under high N plants performed better even under low N test plants. Adult traits including oviposition selection, feeding weight and longevity did not respond to the effects of parental diet nor its interaction with test diet as was the case in the larval stage. However, the main effects of test diet were more important in determining adult performance in both generations suggesting limited sensitivity to parental diet in the adult stage. Our results show conflicting responses to parental diet between larvae and adults of the same generation among an insect species with both actively feeding larval and adult life stages. These transgenerational effects, or lack thereof, may have implications on the field performance of N. abbrevita under heterogeneous nutritional landscapes.


Assuntos
Besouros , Dieta , Herbivoria , Traços de História de Vida , Animais , Feminino , Larva/crescimento & desenvolvimento , Masculino , Nitrogênio , Oviposição
15.
Forensic Sci Int ; 306: 110075, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31794867

RESUMO

The list of factors influencing the development of forensically important insects and the related effects on minimum post mortem (PMImin) estimations is long and well established by various authors in forensic entomology over the last decades. Despite the fact that several authors mention precocious egg development, i.e. first instar larva in the genital tract of some species of Calliphoridae, as a potential error source for PMImin estimations just two studies were performed to examine the occurrence of precocious eggs both in laboratory and field populations of blow flies. In the present study the occurrence of gravid females with precocious eggs in a wild population of Calliphora vicina in Frankfurt am Main was surveyed over 152 days and their seasonal distribution was analyzed as well as the influence of abiotic variables on their abundance. During the sampling occasions, 5.216 females were sampled of which 44 % were gravid. 54 % of all gravid females had a precocious egg/first instar larva in their genital tract. This number varied depending on the season and showed the highest amount in spring with almost 64 % of all gravid females. Hence, precocious eggs in wild populations of blow flies can occur much more frequently than mentioned in forensic literature. Consequences for the evaluation of entomological evidence in forensic casework should not be overrated since focusing alone on the largest larva in a sample is not recommended as the sole reference in an entomological PMImin estimation. The entomological report has to justify its findings, discuss different options and finally state what is considered to be the most likely scenario based on the complete evidence (e.g. including all species and relevant age cohorts as well as succession data) and the case specific history.


Assuntos
Dípteros/fisiologia , Larva/fisiologia , Animais , Dípteros/crescimento & desenvolvimento , Feminino , Larva/crescimento & desenvolvimento , Oviposição/fisiologia , Ovoviviparidade/fisiologia , Óvulo/crescimento & desenvolvimento , Óvulo/fisiologia , Estações do Ano
16.
Oecologia ; 192(1): 1-12, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31773313

RESUMO

Despite being a major selective force, predation can induce puzzling variability in anti-predator responses-from lack of predator aversion to lifelong predator-induced fear. This variability is hypothesised to result from variation in the trade-offs associated with avoiding predators. But critical information on fitness outcomes of these trade-offs associated with anti-predator behaviours is lacking. We tested this trade-off hypothesis in Aedes aegypti, by examining oviposition site selection decisions in response towards larval predation risk and comprehensively measuring the fitness implications of trade-offs of avoiding larval predators, using three fitness measures: larval survival, development time and size. In a field study, we find that adult females show a surprisingly variable response to predators, ranging from attraction to avoidance. This variation is explained by fitness outcomes of oviposition along a predation-risk gradient that we measured in the laboratory. We show that ovipositing females could gain fitness benefits from ovipositing in pools with a low density of predators, rather than in predator-free pools, as predators provide a release from negative density effects of conspecific larvae that might co-occur in a pool. Interacting selection pressures may thus explain diverse prey responses. We suggest other systems in which similarly unexpected prey behaviour is likely to occur.


Assuntos
Oviposição , Comportamento Predatório , Animais , Feminino , Larva
17.
Exp Parasitol ; 208: 107793, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31711973

RESUMO

Praziquantel (PZQ) is the sole drug used to treat schistosomiasis, and the probability of developing resistance is growing the longer it is relied upon, justifying the search for alternatives. Phosphodiesterases (PDEs), particularly the PDE4 family, have attracted considerable attention as drug targets, including in Schistosoma mansoni, and especially SmPDE4A. This study investigates the potential antischistosomal activity of human PDE4 and potent SmPDE4A inhibitor roflumilast, either alone or combined with PZQ. In vitro, roflumilast resulted in a significant, concentration-dependent reduction in egg production but not of worm viability. In vitro exposure to roflumilast in combination with a low concentration of PZQ was less effective than PZQ alone, pointing to antagonism. S. mansoni-infected mice treated with roflumilast showed significant reductions in worm burden (27%) as well as hepatic and intestinal egg burdens (~28%) two weeks post treatment. Scanning EM of worms isolated from roflumilast-treated and untreated mice did not reveal noticeable changes to their tegument. S. mansoni-infected mice treated with a fixed dosage of roflumilast and a variable dosage of PZQ resulted in a higher reduction in worm burden, reduced hepatic egg counts, absence of immature eggs and a marked increase in dead eggs, compared to PZQ alone. However, the combination resulted in increased animal mortality, probably attributable to pharmacodynamic interactions between the two drugs. Although this study marks the first report of in vivo antischistosomal potential by a PDE inhibitor, an important proof of concept, we conclude that the antischistosomal effects of roflumilast are insufficient to warrant further development.


Assuntos
Aminopiridinas/farmacologia , Anti-Helmínticos/farmacologia , Benzamidas/farmacologia , Inibidores da Fosfodiesterase 4/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Animais , Nucleotídeo Cíclico Fosfodiesterase do Tipo 1/antagonistas & inibidores , Nucleotídeo Cíclico Fosfodiesterase do Tipo 1/efeitos dos fármacos , Ciclopropanos/farmacologia , Relação Dose-Resposta a Droga , Feminino , Concentração Inibidora 50 , Masculino , Camundongos , Microscopia Eletrônica de Varredura , Oviposição/efeitos dos fármacos , Praziquantel/farmacologia , Schistosoma mansoni/enzimologia , Schistosoma mansoni/fisiologia , Schistosoma mansoni/ultraestrutura
18.
Parasitol Int ; 74: 101917, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31004804

RESUMO

In the present study, the larvicidal activity of ageing aqueous suspensions of spinosad against larvae of Culex pipiens biotype molestus, as well as their effect on the oviposition preferences of adult gravid females were evaluated in laboratory bioassays. Spinosad was applied at its label dose and the aqueous stock suspensions were stored for various ageing intervals up to 38 days. Untreated distilled water and diflubenzuron served as negative and positive control, respectively. Stock suspensions were taken after 0, 2, 6, 8, 16, 30 and 38 days of storage for diflubenzuron and after 0, 2, 6, 8, 20 and 27 days for spinosad, and were used for the bioassays. Furthermore, the effect of spinosad on the oviposition response of Cx. p. biotype molestus gravid females was investigated in two-choice oviposition preference bioassays. Spinosad was evaluated at half of its label dose and at its label dose, whereas diflubenzuron and distilled water served as positive and negative control, respectively. Results showed that both insecticides were found highly effective for the control of Cx. p. biotype molestus larvae, for ageing intervals up to 27 and 38 days for spinosad and diflubenzuron, respectively. Spinosad acted immediately after the preparation of the insecticidal solution (LT50 = 1.5 h), whereas for aged samples, LT50 values increased with the increase of the ageing interval (LT50 = 5 days for the 27 days old sample). For diflubenzuron, ageing time increased its insecticidal activity, as for aged diflubenzuron-treated solutions, lower LT50 values were achieved. In the oviposition preference bioassays, significantly fewer egg rafts were laid in water treated with spinosad at its label dose compared to control. However, this was not the case for water treated with spinosad at half of its label dose. Oviposition Activity Index (OAI) values were always comprised between -0.3 and 0.3, showing no relevant oviposition deterrence or attraction. The results of the present study contribute to our understanding of the effect of ageing on insecticidal solutions widely used in urban areas to control Cx. p. biotype molestus. Although an important vector of high public health importance, Cx. p. biotype molestus has been scarcely studied as target of environmentally and toxicologically reduced risk insecticides, such as spinosad.


Assuntos
Quitina/antagonistas & inibidores , Culex , Inseticidas/farmacologia , Macrolídeos/farmacologia , Oviposição/efeitos dos fármacos , Animais , Bioensaio , Quitina/biossíntese , Combinação de Medicamentos , Feminino , Larva , Mosquitos Vetores
19.
Pest Manag Sci ; 76(1): 75-84, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31140683

RESUMO

BACKGROUND: Honeydew is valuable food source for predators that can build predator numbers and strengthen biological control. Honeydew excreted by hemipterans often supplements the diets of their predators and parasitoids. However, dense sticky honeydew also creates a difficult foraging environment, potentially limiting predator efficiency. RESULTS: We examined the benefits and costs of honeydew excreted by the pear psylla (Cacopsylla chinensis [Yang and Li]) for its key predator in much of Asia, the anthocorid bug Orius sauteri (Poppius). We found these predators spent more time foraging and laid more eggs in the presence of psyllid honeydew compared to the control. However, predators more often foraged among psylla without honeydew than those coated in honeydew. This suggests that while O. sauteri recognized honeydew as a useful cue to prey presence, the predators were more likely to attack pear psylla lacking the sugary excretion. In foraging trials, honeydew consistently reduced the number of psyllids killed by the predator, suggesting it limited O. sauteri mobility or reduced the nutritional value of psyllids as prey. We also found slowed development, reduced longevity, and reduced fecundity of O. sauteri reared on moth eggs (Sitotroga cerealella [Olivier]) coated in honeydew compared to those reared on moth eggs alone. CONCLUSION: Altogether, our results suggest that psyllid honeydew could serve as a prey-location and oviposition cue for O. sauteri. However, honeydew also limited predator foraging with the potential to limit biological control. More generally, honeydew might form an important type of defense for stationary feeders like psyllids. © 2019 Society of Chemical Industry.


Assuntos
Heterópteros , Pyrus , Animais , Ásia , Feminino , Mariposas , Oviposição
20.
J Chem Ecol ; 45(11-12): 982-992, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31784860

RESUMO

Plants have evolved intricate defence strategies against herbivore attack which can include activation of defence in response to stress-related volatile organic compounds (VOCs) emitted by neighbouring plants. VOCs released by intact molasses grass (Melinis minutiflora), have been shown to repel stemborer, Chilo partellus (Swinhoe), from maize and enhance parasitism by Cotesia sesamiae (Cameron). In this study, we tested whether the molasses grass VOCs have a role in plant-plant communication by exposing different maize cultivars to molasses grass for a 3-week induction period and then observing insect responses to the exposed plants. In bioassays, C. partellus preferred non-exposed maize landrace plants for egg deposition to those exposed to molasses grass. Conversely, C. sesamiae parasitoid wasps preferred volatiles from molasses grass exposed maize landraces compared to volatiles from unexposed control plants. Interestingly, the molasses grass induced defence responses were not observed on hybrid maize varieties tested, suggesting that the effect was not simply due to absorption and re-emission of VOCs. Chemical and electrophysiological analyses revealed strong induction of bioactive compounds such as (R)-linalool, (E)-4,8-dimethyl-1,3,7-nonatriene and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene from maize landraces exposed to molasses grass volatiles. Our results suggest that constitutively emitted molasses grass VOCs can induce direct and indirect defence responses in neighbouring maize landraces. Plants activating defences by VOC exposure alone could realize enhanced levels of resistance and fitness compared to those that launch defence responses upon herbivore attack. Opportunities for exploiting plant-plant signalling to develop ecologically sustainable crop protection strategies against devastating insect pests such as stemborer C. partellus are discussed.


Assuntos
Compostos Orgânicos Voláteis/química , Zea mays/metabolismo , /química , Animais , Produtos Agrícolas , Feminino , Cromatografia Gasosa-Espectrometria de Massas/métodos , Herbivoria , Interações Hospedeiro-Parasita , Melaço , Mariposas/parasitologia , Oviposição/efeitos dos fármacos , Compostos Orgânicos Voláteis/metabolismo , Vespas/fisiologia , Zea mays/parasitologia
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