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1.
Pestic Biochem Physiol ; 163: 185-192, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31973856

RESUMO

Biological control potential of entomopathogenic fungi depending on conidiation capacity, conidial stress tolerance and virulence can be improved through genetic engineering. To explore a possible role of trehalose biosynthesis pathway in improving fungal pest-control potential, we characterized biological functions of trehalose-6-phosphate phosphatase (BbTPP) in Beauveria bassiana, an insect mycopathogen that serves as a main source of fungal insecticides. Deletion of BbTPP resulted in abolished trehalose biosynthesis, reduced conidiation capacity, decreases in conidial thermotolerance and UV-B resistance, increased hyphal sensitivities to chemical stresses, and attenuated virulence. By contrast, over-expression of BbTPP led to increased trehalose accumulation, decreased T6P accumulation, and enhanced stress tolerance and virulence despite little impact on growth and conidiation under normal conditions. These results indicate that BbTPP serves as not only a key player in control of trehalose biosynthesis required for multiple cellular functions but also a potential candidate to be exploited for genetic improvement of fungal potential against insect pests.


Assuntos
Estresse Fisiológico , Trealose , Animais , Proteínas Fúngicas , Deleção de Genes , Insetos , Monoéster Fosfórico Hidrolases , Esporos Fúngicos , Virulência
2.
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
4.
Nat Commun ; 11(1): 576, 2020 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-31996690

RESUMO

Urbanisation is an important global driver of biodiversity change, negatively impacting some species groups whilst providing opportunities for others. Yet its impact on ecosystem services is poorly investigated. Here, using a replicated experimental design, we test how Central European cities impact flying insects and the ecosystem service of pollination. City sites have lower insect species richness, particularly of Diptera and Lepidoptera, than neighbouring rural sites. In contrast, Hymenoptera, especially bees, show higher species richness and flower visitation rates in cities, where our experimentally derived measure of pollination is correspondingly higher. As well as revealing facets of biodiversity (e.g. phylogenetic diversity) that correlate well with pollination, we also find that ecotones in insect-friendly green cover surrounding both urban and rural sites boost pollination. Appropriately managed cities could enhance the conservation of Hymenoptera and thereby act as hotspots for pollination services that bees provide to wild flowers and crops grown in urban settings.


Assuntos
Abelhas/fisiologia , Ecologia , Insetos/fisiologia , Polinização , Urbanização , Animais , Abelhas/classificação , Biodiversidade , Cidades , Dípteros , Ecossistema , Flores , Alemanha , Himenópteros , Insetos/classificação , Lepidópteros , Filogenia
5.
J Agric Food Chem ; 68(5): 1169-1185, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31922733

RESUMO

Epichloë endophytes in forage grasses have attracted widespread attention and interest of chemistry researchers as a result of the various unique chemical structures and interesting biological activities of their secondary metabolites. This review describes the diversity of unique chemical structures of taxa from Epichloë endophytes and grass infected with Epichloë endophytes and demonstrates their reported biological activities. Until now, nearly 160 secondary metabolites (alkaloids, peptides, indole derivatives, pyrimidines, sesquiterpenoids, flavonoids, phenol and phenolic acid derivatives, aliphatic metabolites, sterols, amines and amides, and others) have been reported from Epichloë endophytes and grass infected with Epichloë endophytes. Among these, non-alkaloids account for half of the population of total metabolites, indicating that they also play an important role in Epichloë endophytes and grass infected with Epichloë endophytes. Also, a diverse array of secondary metabolites isolated from Epichloë endophytes and symbionts is a rich source for developing new pesticides and drugs. Bioassays disclose that, in addition to toxic alkaloids, the other metabolites isolated from Epichloë endophytes and symbionts have notable biological activities, such as antifungal, anti-insect, and phytotoxic activities. Accordingly, the biological functions of non-alkaloids should not be neglected in the future investigation of Epichloë endophytes and symbionts.


Assuntos
Alcaloides/metabolismo , Endófitos/química , Epichloe/química , Poaceae/microbiologia , Simbiose , Alcaloides/química , Alcaloides/toxicidade , Animais , Endófitos/fisiologia , Epichloe/metabolismo , Insetos/efeitos dos fármacos , Gado/metabolismo , Poaceae/fisiologia
6.
Forensic Sci Int ; 306: 110033, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31812085

RESUMO

Three vehicles with trunks containing pig (Sus scrofa domesticus Erxleben) carcasses which had been allowed to decompose for 30 days, were set alight in controlled burns to determine whether forensically valuable insect evidence could still be recovered. Each car trunk contained the remains of a carcass, together with its associated carrion insect fauna. An insect collection was performed prior to the fires. Each car was then set alight using a small amount of gasoline as an accelerant, poured onto the driver's seat, lit by a burning stick. The fire was allowed to reach its peak before being extinguished. In all cases, the fires completely destroyed the vehicles. The vehicles were examined the following day and insect evidence was collected. In all cases, large amounts of burned, charred and undamaged insect evidence remained, including identifiable prepuparial 3rd instar larvae, live pupae inside intact puparia and empty puparial cases. As well bones and unburned clothing were also intact. One car did not burn as well as the others with the fire not involving the trunk area as much as in the other cars. Once the fire was extinguished, it was clear that the reason for this was the presence of a steel fire wall, between the passenger compartment and the trunk. This reduced the spread of the fire to the trunk and increased evidence survival. However, in all vehicles, insect evidence survived, which could still be used to estimate the period of insect colonization and thereby infer the minimum elapsed time since death. The evidence was also a clear indicator that the decedent had not died in the fire. After the fire, the carcass remains were still attractive to blow fly adults (Diptera: Calliphoridae). In car fire cases it is important to consider that entomological evidence may still be just as useful in the investigation as in non-burned cases.


Assuntos
Automóveis , Espaços Confinados , Fogo , Insetos , Mudanças Depois da Morte , Animais , Queimaduras , Crime , Comportamento Alimentar , Larva , Modelos Animais , Pupa , Suínos
7.
Waste Manag ; 102: 198-203, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31678806

RESUMO

An estimation of the economy of Hermetia illucens and Chlorella pyrenoidosa cultivations as food waste treatment with benefits was carried out. For both organisms, a process scale was assumed to treat 56.3 t of wet food waste per day, which is equivalent to the amount of food waste appearing in a catchment area of 141,000 inhabitants. Using hypothetical insect and heterotrophic microalgae cultivation processes, a daily production of 3.64 t and 7.14 t dried biomass, respectively, can be achieved. For the cultivation of H. illucens, equipment and daily operational costs were estimated at 79,358.15 € and 5,281.56 €, respectively. Equipment and operational costs for the C. pyrenoidosa cultivation was 50 and 6 times higher, respectively. The higher costs reflect the more complex and advanced process compared to H. illucens cultivation. The internal return rate for a plant lifetime of 20 times revealed an economic benefit when C. pyrenoidosa biomass is produced. Nevertheless, both processes were found economically feasible when dried biomass is directly commercialized as food without any further downstream processing. However, extraction and purification of special chemicals, such as unsaturated fatty acids and pigments, can significantly increase the revenue.


Assuntos
Chlorella , Microalgas , Eliminação de Resíduos , Animais , Biomassa , Alimentos , Processos Heterotróficos , Insetos , Águas Residuárias
8.
Forensic Sci Int ; 306: 110046, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31734574

RESUMO

Murderers sometimes dispose of bodies in zipped suitcases in an attempt to conceal their crimes. In these cases, the species of insects found and their succession patterns are typically different from those found on exposed corpses due to hindrances or delays in colonization. Here we report a case in which an unidentified female corpse was found in a soft-shell suitcase in a wetland area among some reeds in Guangdong, China on 13 May 2018. The suitcase was unbroken and zippers were well-sealed. The victim was a young woman, naked, and curled up in the suitcase. The insect evidence we collected include (i) pupae and empty puparia of Chrysomya nigripes (Aubertin) (Diptera: Calliphoridae) and Fannia canicularis (Linnaeus) (Diptera, Muscidae), (ii) larvae, pupae and empty puparia of Megaselia scalaris (Loew) (Diptera: Phoridae) and Hermetia illucens (Linnaeus) (Diptera: Stratiomyidae). According to this insect evidence, we estimated the PMImin as 56 days. Bhadra et al. (2014) show that larvae of Calliphora vomitoria (Linnaeus) (Diptera: Calliphoridae) and Calliphora vicina (Robineau-Desvoidy) (Diptera, Calliphoridae) can colonize carcasses concealed in zipped suitcases. Although the size of the zipper (7mm) in this case is larger than that described in Bhadra et al. (4mm), we did not find Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae), Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae), or Lucilia sericata (Meigen) (Diptera: Calliphoridae) which usually colonize fresh corpses in this area. Therefore, we deduced that the victim may have been killed in winter. After the crime was solved, the murderer confessed that he killed the victim on 5 January.


Assuntos
Cadáver , Comportamento Alimentar/fisiologia , Insetos/fisiologia , Mudanças Depois da Morte , Animais , China , Homicídio , Humanos , Temperatura Ambiente
9.
Phytopathology ; 110(1): 29-48, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31544593

RESUMO

The pathological importance of mixed viral infections in plants might be underestimated except for a few well-characterized synergistic combinations in certain crops. Considering that the host ranges of many viruses often overlap and that most plant species can be infected by several unrelated viruses, it is not surprising to find more than one virus simultaneously in the same plant. Furthermore, dispersal of the majority of plant viruses relies on efficient transmission mechanisms mediated by vector organisms, mainly but not exclusively insects, which can contribute to the occurrence of multiple infections in the same plant. Recent work using different experimental approaches has shown that mixed viral infections can be remarkably frequent, up to the point that they could be considered the rule more than the exception. The purpose of this review is to describe the impact of multiple infections not only on the participating viruses themselves but also on their vectors and on the common host. From this standpoint, mixed infections arise as complex events that involve several cross-interacting players, and they consequently require a more general perspective than the analysis of single-virus/single-host approaches for a full understanding of their relevance.


Assuntos
Coinfecção , Doenças das Plantas , Vírus de Plantas , Animais , Insetos/virologia , Doenças das Plantas/virologia
10.
Sci Total Environ ; 701: 135044, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31726403

RESUMO

Insects play an important role in the spread of viruses from infected plants to healthy hosts through a variety of transmission strategies. Environmental factors continuously influence virus transmission and result in the establishment of infection or disease. Plant virus diseases become epidemic when viruses successfully dominate the surrounding ecosystem. Plant-insect vector-virus interactions influence each other; pushing each other for their benefit and survival. These interactions are modulated through environmental factors, though environmental influences are not readily predictable. This review focuses on exploiting the diverse relationships, embedded in the plant-insect vector-virus triangle by highlighting recent research findings. We examined the interactions between viruses, insect vectors, and host plants, and explored how these interactions affect their behavior.


Assuntos
Mudança Climática , Insetos Vetores , Vírus dos Insetos , Vírus de Plantas , Animais , Ecossistema , Interações Hospedeiro-Patógeno , Insetos , Doenças das Plantas , Plantas
11.
Chemosphere ; 239: 124799, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31518926

RESUMO

Terrestrial adult stages of freshwater insects may be exposed to pesticides by wind drift, over-spray, contact or feeding. However, studies addressing insecticide effects on freshwater invertebrates focus primarily on the impact of pesticides reaching the streams and potentially harming the aquatic juvenile stages. This is also reflected in the current risk assessment procedures, which do not include testing of adult freshwater insects. In order to assess the potential impact of insecticides on adult stages of freshwater insects, we exposed six common species to the insecticides Karate (lambda-cyhalothrin) and Confidor (imidacloprid). Dose-response relations were established, and LD50 estimates were compared to those of the honey bee, Apis mellifera L. (Hymenoptera: Apidae), which is the standard terrestrial test insect when pesticides are evaluated prior to commercial release. Generally, the tested species were more sensitive to the studied insecticides than the honey bee. In order to examine whether the sensitivity of adult stages of freshwater insects corresponds with the sensitivity of the juvenile stages of the same species, the ranking of the two life stages with respect to the toxicity of Karate was compared, revealing some correspondence, but also some dissimilarities. Our results strongly indicate that terrestrial adult stages of aquatic insects are not adequately protected by current risk assessment procedures.


Assuntos
Insetos/efeitos dos fármacos , Insetos/fisiologia , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrilos/toxicidade , Nitrocompostos/toxicidade , Piretrinas/toxicidade , Animais , Abelhas/efeitos dos fármacos , Dinamarca , Relação Dose-Resposta a Droga , Ecotoxicologia/métodos , Inseticidas/administração & dosagem , Dose Letal Mediana , Neonicotinoides/administração & dosagem , Nitrilos/administração & dosagem , Nitrocompostos/administração & dosagem , Piretrinas/administração & dosagem , Rios , Especificidade da Espécie , Poluentes Químicos da Água/toxicidade
12.
Chemosphere ; 240: 124926, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726586

RESUMO

Insect pollinators such as bees and syrphid flies play a crucial role in pollinating many food crops, and their diversity and abundance may be influenced by pesticide application patterns. Over three years, we assessed the ecotoxicological impacts on the diversity and abundance of bees and syrphid flies between reduced-risk pesticide programs and standard, conventional pesticide programs in paired plots at six spatially distinct commercial apple orchards. In particular, we quantified pesticide inputs, environmental impact, and community response of bees and syrphids to these pesticide programs. Relative environmental impacts of reduced-risk versus conventional pesticide programs were calculated using Environmental Impact Quotient analysis, while ecological impacts were characterized by assessing the abundance, richness, and species assemblages of bees and syrphids. Adopting a reduced-risk pesticide program for apple pest management reduced the use (in terms of kg a.i./ha) of organophosphate and pyrethroid insecticides by approximately 97.6% and 100% respectively, but increased the use of neonicotinoid pesticides (acetamiprid, imidacloprid, thiacloprid) by 40.4% compared to the orchards under standard conventional pesticide program. Regardless of pesticide inputs, abundance, richness and species assemblages of bees and syrphids did not differ between reduced-risk and conventional pest management programs. However, the environmental impact of pesticide inputs was reduced by 89.8% in reduced-risk pesticide program. These findings suggest that the implementation of reduced-risk pesticide program may reduce pesticide environmental impact, in addition to being safer to farm workers, without adversely affecting the robust community composition of bees and syrphids in commercial apple orchards in the mid-Atlantic region.


Assuntos
Produtos Agrícolas , Malus , Controle de Pragas/métodos , Praguicidas , Polinização , Animais , Abelhas , Ecotoxicologia , Meio Ambiente , Insetos , Inseticidas , Neonicotinoides , Nitrocompostos , Piretrinas , Tiazinas
13.
Food Chem ; 303: 125381, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31473459

RESUMO

To reduce food loss from stored products by insect attack, monitoring and early detection of insects are essential. Presently, monitoring with pheromone traps is the primary method for detection; however, traps are effective only after the insects propagate. Detection and identification of the early volatile biomarkers arising from insect-infested brown rice was performed in this study to develop an alternative detection strategy. Brown rice was infested with eggs of seven insect species, including Sitophilus zeamais and Plodia interpunctella. Infested rice emitted at least one of the volatile compounds prenol, isoprenol, dimethyl disulfide, and dimethyl trisulfide (DMTS). In particular, isopentenols were generated by moths within one week of infestation, whereas they were not released from non-infested rice. DMTS was detected from all insect-infested brown rice, especially S. zeamais and P. interpunctella. These volatiles are potential early biomarkers for the presence of insects in brown rice.


Assuntos
Contaminação de Alimentos/análise , Insetos/metabolismo , Oryza , Pentanóis/análise , Sulfetos/análise , Animais , Biomarcadores/análise , Biomarcadores/metabolismo , Dissulfetos/análise , Dissulfetos/metabolismo , Hemiterpenos , Insetos/fisiologia , Larva/metabolismo , Pentanóis/metabolismo , Sulfetos/metabolismo , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/metabolismo
14.
Chemosphere ; 240: 124813, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31542576

RESUMO

Hexabromocyclododecane (HBCDD) has frequently been detected in wildlife. However, there is limited research on its bioaccumulation and biomagnification in insect-dominated aquatic and terrestrial food webs. This study investigated the occurrence of HBCDD in insects and their predators collected from a former e-waste contaminated pond and its surrounding region. The concentrations of Æ©HBCDD (sum concentrations of α-, ß-, and γ-HBCDDs) ranged from nd to 179 ng g-1 lipid weight. α-HBCDD was the predominant diastereoisomer in all biotic samples, and the contribution of α-HBCDD was higher in predators than in prey insects. A significantly positive linear relationship was found between Æ©HBCDD concentrations (lipid weight) and trophic levels based on δ15N in aquatic organisms (p < 0.05), while trophic dilution was observed in the terrestrial food web. This result indicates an opposite trophic transfer tendency of HBCDD in terrestrial and aquatic ecosystems. The biomagnification factor (BMF) for α-HBCDD was higher in terrestrial birds (2.03) than in frogs (0.29), toads (0.85), and lizards (0.63). This may be due to differences between poikilotherms and homeotherms in terrestrial ecosystems.


Assuntos
Resíduo Eletrônico/efeitos adversos , Hidrocarbonetos Bromados/química , Insetos/patogenicidade , Animais , Bioacumulação , China , Ecossistema , Resíduo Eletrônico/análise , Cadeia Alimentar , Humanos
15.
Pestic Biochem Physiol ; 162: 86-95, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31836059

RESUMO

RNA interference (RNAi) efficiency varies among insects. RNAi is highly efficient and systemic in coleopteran insects but quite variable and inefficient in lepidopteran insects. Degradation of double-stranded RNA (dsRNA) by double-stranded ribonucleases (dsRNases) is thought to contribute to the variability in RNAi efficiency observed among insects. One or two dsRNases involved in dsRNA digestion have been identified in a few insects. To understand the contribution of dsRNases to reduced RNAi efficiency in lepidopteran insects, we searched the transcriptome of Spodoptera litura and identified six genes coding for DNA/RNA non-specific endonucleases. Phylogenetic analysis revealed the evolutionary expansion of dsRNase genes in insects. The mRNA levels of three midgut-specific dsRNases increased during the larval stage, and the highest dsRNA-degrading activity was detected in third-instar larvae. Proteins produced via the expression of three midgut-specific dsRNases, and the widely expressed dsRNase3, in a baculovirus system showed dsRNase activity for four out of five dsRNases tested. In addition, the increase in dsRNA-degrading activity and upregulation of dsRNase1 and 2 in larvae fed on cabbage leaves suggests that the diet of S. litura can influence dsRNase expression, dsRNA stability, and thus probably RNAi efficiency. This is the first report that multiple dsRNases function together in an RNAi-recalcitrant insect. The data included in this paper suggest that multiple dsRNases coded by the S. litura genome might contribute to the lower and variable RNAi efficiency reported in this and other lepidopteran insects.


Assuntos
Proteínas de Insetos , Tabaco , Animais , Insetos , Larva , Filogenia , Interferência de RNA , RNA de Cadeia Dupla , Spodoptera
16.
Ecol Lett ; 23(1): 149-159, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31692246

RESUMO

Conflicts of interests between males and females over reproduction is a universal feature of sexually reproducing organisms and has driven the evolution of intersexual mimicry, mating behaviours and reproductive polymorphisms. Here, we show how temperature drives pre-reproductive selection in a female colour polymorphic insect that is subject to strong sexual conflict. These species have three female colour morphs, one of which is a male mimic. This polymorphism is maintained by frequency-dependent sexual conflict caused by male mating harassment. The frequency of female morphs varies geographically, with higher frequency of the male mimic at higher latitudes. We show that differential temperature sensitivity of the female morphs and faster sexual maturation of the male mimic increases the frequency of this morph in the north. These results suggest that sexual conflict during the adult stage is shaped by abiotic factors and frequency-independent pre-reproductive selection that operate earlier during ontogeny of these female morphs.


Assuntos
Polimorfismo Genético , Reprodução , Animais , Impulso (Psicologia) , Feminino , Insetos , Masculino , Temperatura Ambiente
17.
Arch Insect Biochem Physiol ; 103(1): e21622, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31583765

RESUMO

Eicosanoids, a group of C20 oxygenated polyunsaturated fatty acids (PUFAs), mediate various physiological processes, such as immunity, reproduction, excretion, and metabolism in insects. Arachidonic acid (AA) is used for the main precursor for the production of various eicosanoids. However, most terrestrial insects possess relatively low AA levels. Insects are presumed to be evolved since the Paleozoic era, at which oxygen levels might be much higher than current conditions. Compared with other animals, they exhibit relatively high metabolic rates with the well-developed tracheal system, which directly supply enough oxygen to active tissues like flight muscles. This might allow insects to be susceptible to reactive oxygen species (ROS) generated from high oxidative catabolism. Long-chain PUFAs including AA is usually reacted with ROS and become peroxidized. Peroxidized PUFAs cause various cellular damage. Thus, we propose a hypothesis that terrestrial insects minimize AA levels to minimize oxidative stress.


Assuntos
Ácidos Graxos Insaturados/metabolismo , Insetos/metabolismo , Estresse Oxidativo , Animais , Ácido Araquidônico/metabolismo , Metabolismo Basal , Espécies Reativas de Oxigênio/metabolismo , Fenômenos Fisiológicos Respiratórios
18.
Biol Lett ; 15(12): 20190572, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31847747

RESUMO

Phenological differences between host plants can promote temporal isolation among host-associated populations of insects with life cycles tightly coupled to plant phenology. Divergence in the timing of spring budbreak between two sympatric sister oak species has been shown to promote temporal isolation between host plants and their host-associated populations of a cynipid gall wasp. Here, we examined the generality of this mechanism by testing the hypothesis of cascading temporal isolation for five additional gall-formers and three natural enemy species associated with these same oak species. The timing of adult emergence from galls differed significantly between host-associated populations for all nine species and parallels the direction of the phenological differences between host plants. Differences in emergence timing can reduce gene flow between host-associated populations by diminishing mating opportunities and/or reducing the fitness of immigrants due to differences in the availability of ephemeral resources. Our study suggests that cascading temporal isolation could be a powerful 'biodiversity generator' across multiple trophic levels in tightly coupled plant-insect systems.


Assuntos
Insetos , Vespas , Animais , Interações Hospedeiro-Parasita , Plantas , Simpatria
19.
20.
J Agric Food Chem ; 67(50): 13914-13921, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31757122

RESUMO

Ethyl formate (EF) is a generally recognized-as-safe flavoring agent commonly used in the food industry. It is a naturally occurring volatile with insecticidal and antimicrobial properties, promising as an alternate fumigant to methyl bromide which is undesirable due to its ozone depletion in the stratosphere and toxic properties. However, EF is highly volatile, flammable, and susceptible to hydrolytic degradation. These properties present considerable end-use challenges. In this study, a precursor of EF was synthesized via the condensation reaction of adipic acid dihydrazide and triethyl orthoformate to form diethyl N,N'-adipoyldiformohydrazonate, as confirmed by Fourier transformed infrared and solid-state nuclear magnetic resonance spectroscopies. Differential scanning calorimetry analysis showed that the precursor had a melting point of 174 °C. The physical properties of the precursor were studied using scanning electron microscopy and dynamic light scattering analysis, which showed that the precursor was made up of agglomerated particulates with irregular shapes and sizes. The resulting precursor was nonvolatile and remained stable under dry conditions but could be hydrolyzed readily to trigger the release of EF. The release behaviors of EF from the precursor was evaluated by citric acid-catalyzed hydrolysis, showing that 0.38 ± 0.008 mg EF/mg precursor was released after 2 h at 25 °C, representing about 98% of the theoretical loading. Both EF release rate and its total release amount decreased significantly (p < 0.05) with decreasing temperature and relative humidity. The conversion of the highly volatile EF into a solid-state precursor, in conjunction with the activated release strategy, can be useful for controlled release of EF for fumigation and other applications in destroying insect pests and inhibiting the proliferation of spoilage microorganisms.


Assuntos
Preparações de Ação Retardada/química , Preparações de Ação Retardada/síntese química , Ésteres do Ácido Fórmico/química , Inseticidas/síntese química , Animais , Preparações de Ação Retardada/farmacologia , Ésteres do Ácido Fórmico/farmacologia , Fumigação , Controle de Insetos , Insetos/efeitos dos fármacos , Inseticidas/química , Inseticidas/farmacologia
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