Herbivore‐induced plant volatiles prime neighbouring plants to respond more strongly to subsequent attacks. However, the key volatiles that trigger this state and their priming mechanisms remain ...largely unknown. The tea geometrid Ectropis obliqua is one of the most devastating leaf‐feeding pests of tea plants. Here, plant–plant communication experiments demonstrated that volatiles emitted from tea plants infested by E. obliqua larvae triggered neighbouring plants to release volatiles that repel E. obliqua adult, especially mated females. Volatile analyses revealed that the quantity of eight volatiles increased dramatically when plants were exposed to volatiles emitted by infested tea plants, including (Z)‐3‐hexenol, linalool, α‐farnesene, β‐Ocimene and (E)‐4,8‐dimethyl‐1,3,7‐nonatriene (DMNT). The results of behavioural bioassays demonstrated that β‐Ocimene strongly repelled mated E. obliqua females. Individual volatile compound exposure experiments revealed that (Z)‐3‐hexenol, linalool, α‐farnesene and DMNT triggered the emission of β‐Ocimene from tea plants. Chemical inhibition experiments demonstrated that the emission of β‐Ocimene induced by (Z)‐3‐hexenol, linalool, α‐farnesene and DMNT were dependent on Ca2+ and JA signalling. These findings help us to understand how E. obliqua moths respond to volatiles emitted from tea plants and provide new insight into volatile‐mediated plant–plant interactions. They have potential significance for the development of novel insect and pest control strategies in crops.
Herbivore‐induced plant volatiles (HIPVs) play important ecological roles in defense against stresses and prime neighboring intact plants to respond more strongly to subsequent attacks. However, the key volatiles that trigger this primed state and their priming mechanisms remain largely unknown. Here, plant–plant communication experiments demonstrated that volatiles emitted from tea plants infested by Ectropis obliqua larvae triggered neighboring intact plants to release volatiles that repel E. obliqua mated females. The results of behavioral bioassays demonstrated that β‐Ocimene strongly repelled mated E. obliqua females. Here, we provide the first evidence for the HIPVs triggered the emission of β‐Ocimene from the primed plants. Chemical inhibition experiments demonstrated that the emission of β‐Ocimene induced by these volatiles was dependent on Ca2+ and JA signaling in primed plants. The knowledge will help us to understand how E. obliqua female moths respond to volatile cues emitted from tea plants and provide new insight into volatile‐mediated plant–plant interactions.
The diamondback moth, Plutella xylostella, has developed extremely high levels of resistance to chlorantraniliprole and other classes of insecticides in the field. As microRNAs (miRNAs) play ...important roles in various biological processes through gene regulation, we examined the miRNA profile of P. xylostella in response to chlorantraniliprole exposure. RNA sequencing analysis showed that insecticide treatment caused significant changes in the abundance of some miRNAs. Increasing exposure time and insecticide concentration induced more dysregulated miRNAs in P. xylostella larvae. We also screened potential target genes for some of the differentially expressed miRNAs (such as miR‐2b‐3p, miR‐14b‐5p and let‐7‐5p), which may play important roles in insecticide resistance development. Exposure of P. xylostella larvae to chlorantraniliprole caused considerable overexpression in the transcript levels of potential target genes cytochrome P450 9f2 (CYP9F2) and 307a1 (CYP307a1). Application of miR‐2b‐3p and miR‐14b‐5p mimics significantly suppressed the relative transcript levels of CYP9F2 and CYP307a1, respectively, in a P. xylostella cell line. Furthermore, enrichment of P. xylostella diet with miR‐2b‐3p mimics significantly increased mortality in deltamethrin‐resistant larvae when exposed to deltamethrin. The results suggest that miR‐2b‐3p may suppress CYP9F2 transcript levels in P. xylostella and consequently inhibit larval detoxification pathways. The findings provide an insight into possible role of miRNAs in regulation of metabolic resistance of insects to insecticides.
Nectar-feeding animals have among the highest recorded metabolic rates. High aerobic performance is linked to oxidative damage in muscles. Antioxidants in nectar are scarce to nonexistent. We propose ...that nectarivores use nectar sugar to mitigate the oxidative damage caused by the muscular demands of flight. We found that sugar-fed moths had lower oxidative damage to their flight muscle membranes than unfed moths. Using respirometry coupled with δ13C analyses, we showed that moths generate antioxidant potential by shunting nectar glucose to the pentose phosphate pathway (PPP), resulting in a reduction in oxidative damage to the flight muscles. We suggest that nectar feeding, the use of PPP, and intense exercise are causally linked and have allowed the evolution of powerful fliers that feed on nectar.
Cadherins have been identified as receptors of Bacillus thuringiensis (Bt) Cry1A toxins in several lepidopteran insects including the cotton bollworm, Helicoverpa armigera. Disruption of the cadherin ...gene HaCad has been genetically linked to resistance to Bt toxin Cry1Ac in H. armigera. By using the CRISPR/Cas9 genome editing system (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9), HaCad from the Cry1Ac-susceptible SCD strain of H. armigera was successfully knocked out. A single positive CRISPR event with a frame shift deletion of 4 nucleotides was identified and made homozygous to create a knockout line named SCD-Cad. Western blotting confirmed that HaCad was no longer expressed in the SCD-Cad line while an intact HaCad of 210 kDa was present in the parental SCD strain. Insecticide bioassays were used to show that SCD-Cad exhibited 549-fold resistance to Cry1Ac compared with SCD, but no significant change in susceptibility to Cry2Ab. Our results not only provide strong reverse genetics evidence for HaCad as a functional receptor of Cry1Ac, but also demonstrate that the CRISPR/Cas9 technique can act as a powerful and efficient genome editing tool to study gene function in a global agricultural pest, H. armigera.
Display omitted
•Cadherin gene HaCad from Helicoverpa armigera was knocked out by CRISPR/Cas9.•Knockout of HaCad resulted in 549-fold resistance to Cry1Ac.•Knockout of HaCad did not change susceptibility to Cry2Ab.
Physiological research suggests that tropical insects are particularly sensitive to temperature, but information on their responses to climate change has been lacking--even though the majority of all ...terrestrial species are insects and their diversity is concentrated in the tropics. Here, we provide evidence that tropical insect species have already undertaken altitude increases, confirming the global reach of climate change impacts on biodiversity. In 2007, we repeated a historical altitudinal transect, originally carried out in 1965 on Mount Kinabalu in Borneo, sampling 6 moth assemblages between 1,885 and 3,675 m elevation. We estimate that the average altitudes of individuals of 102 montane moth species, in the family Geometridae, increased by a mean of 67 m over the 42 years. Our findings indicate that tropical species are likely to be as sensitive as temperate species to climate warming, and we urge ecologists to seek other historic tropical samples to carry out similar repeat surveys. These observed changes, in combination with the high diversity and thermal sensitivity of insects, suggest that large numbers of tropical insect species could be affected by climate warming. As the highest mountain in one of the most biodiverse regions of the world, Mount Kinabalu is a globally important refuge for terrestrial species that become restricted to high altitudes by climate warming.
Polyethylene (PE) has been considered nonbiodegradable for decades. Although the biodegradation of PE by bacterial cultures has been occasionally described, valid evidence of PE biodegradation has ...remained limited in the literature. We found that waxworms, or Indian mealmoths (the larvae of Plodia interpunctella), were capable of chewing and eating PE films. Two bacterial strains capable of degrading PE were isolated from this worm’s gut, Enterobacter asburiae YT1 and Bacillus sp. YP1. Over a 28-day incubation period of the two strains on PE films, viable biofilms formed, and the PE films’ hydrophobicity decreased. Obvious damage, including pits and cavities (0.3–0.4 μm in depth), was observed on the surfaces of the PE films using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The formation of carbonyl groups was verified using X-ray photoelectron spectroscopy (XPS) and microattenuated total reflectance/Fourier transform infrared (micro-ATR/FTIR) imaging microscope. Suspension cultures of YT1 and YP1 (108 cells/mL) were able to degrade approximately 6.1 ± 0.3% and 10.7 ± 0.2% of the PE films (100 mg), respectively, over a 60-day incubation period. The molecular weights of the residual PE films were lower, and the release of 12 water-soluble daughter products was also detected. The results demonstrated the presence of PE-degrading bacteria in the guts of waxworms and provided promising evidence for the biodegradation of PE in the environment.
In the present work, we have investigate the cellular immune response of
Galleria mellonella
larvae against three strains of the gram-negative bacterium
Actinobacillus pleuropneumoniae
: ...low-virulence (780), high-virulence (1022) and the serotype 8 reference strain (R8). Prohemocytes, plasmatocytes, granulocytes, oenocytoids and spherulocytes were distinguished according to their size and morphology, their molecular markers and dye-staining properties and their role in the immune response. Total hemocyte count, differential hemocyte count, lysosome activity, autophagic response, cell viability and caspase-3 activation were determined in circulating hemocytes of naive and infected larvae. The presence of the autophagosome protein LC3 A/B within the circulating hemocytes of
G. mellonella
was dependent on and related to the infecting
A. pleuropneumoniae
strain and duration of infection. Hemocytes treated with the high-virulence strain expressed higher levels of LC3 A/B, whereas treatment with the low-virulence strain induced lower expression levels of this protein in the cells. Moreover, our results showed that apoptosis in circulating hemocytes of
G. mellonella
larvae after exposure to virulent bacterial strains occurred simultaneously with excessive cell death response induced by stress and subsequent caspase-3 activation.
Little is known about the role of specific delta GST genes in the detoxification of lambda-cyhalothrin in the global quarantine fruit pest codling moth, Cydia pomonella (L.). Real-time quantitative ...PCR shows that CpGSTd3 was ubiquitously expressed at all developmental stages and is most abundant in the larval stage and lowest in the egg stage; the mRNA level of CpGSTd3 is higher in the midgut and Malpighian tubules of fourth-instar larvae and abdomens of adults than in other tissues. Exposure of fourth-instar larvae to an LD10 dosage of lambda-cyhalothrin significantly induced the transcript of CpGSTd3 at 3 h, but the mRNA level was down-regulated after 12 h of treatment. Recombinant CpGSTd3 expressed in Escherichia coli was able to catalyze the conjugation of 1-chloro-2,4-dinitrobenzene (CDNB) and with an IC50 value of 0.65 mM for lambda-cyhalothrin. Metabolism assays indicate that recombinant CpGSTd3 could metabolize lambda-cyhalothrin. These results suggest that CpGSTd3 is probably a lambda-cyhalothrin metabolizing GST in C. pomonella.
ABSTRACT
Butterflies and moths (Lepidoptera) are one of the most studied, diverse, and widespread animal groups, making them an ideal model for climate change research. They are a particularly ...informative model for studying the effects of climate change on species ecology because they are ectotherms that thermoregulate with a suite of physiological, behavioural, and phenotypic traits. While some species have been negatively impacted by climatic disturbances, others have prospered, largely in accordance with their diversity in life‐history traits. Here we take advantage of a large repertoire of studies on butterflies and moths to provide a review of the many ways in which climate change is impacting insects, animals, and ecosystems. By studying these climate‐based impacts on ecological processes of Lepidoptera, we propose appropriate strategies for species conservation and habitat management broadly across animals.
Pheromones are central to the mating systems of a wide range of organisms, and reproductive isolation between closely related species is often achieved by subtle differences in pheromone composition. ...In insects and moths in particular, the use of structurally similar components in different blend ratios is usually sufficient to impede gene flow between taxa. To date, the genetic changes associated with variation and divergence in pheromone signals remain largely unknown. Using the emerging model system Ostrinia , we show the functional consequences of mutations in the protein-coding region of the pheromone biosynthetic fatty-acyl reductase gene pgFAR . Heterologous expression confirmed that pgFAR orthologs encode enzymes exhibiting different substrate specificities that are the direct consequences of extensive nonsynonymous substitutions. When taking natural ratios of pheromone precursors into account, our data reveal that pgFAR substrate preference provides a good explanation of how species-specific ratios of pheromone components are obtained among Ostrinia species. Moreover, our data indicate that positive selection may have promoted the observed accumulation of nonsynonymous amino acid substitutions. Site-directed mutagenesis experiments substantiate the idea that amino acid polymorphisms underlie subtle or drastic changes in pgFAR substrate preference. Altogether, this study identifies the reduction step as a potential source of variation in pheromone signals in the moth genus Ostrinia and suggests that selection acting on particular mutations provides a mechanism allowing pheromone reductases to evolve new functional properties that may contribute to variation in the composition of pheromone signals.
PDF
