To investigate N metabolism of two contrasting Populus species in acclimation to low N availability, saplings of slow-growing species (Populus popularis, Pp) and a fast-growing species (Populus alba ...× Populus glandulosa, Pg) were exposed to 10, 100, or 1000 μM NH4NO3. Despite greater root biomass and fine root surface area in Pp, lower net influxes of NH4 + and NO3 – at the root surface were detected in Pp compared to those in Pg, corresponding well to lower NH4 + and NO3 – content and total N concentration in Pp roots. Meanwhile, higher stable N isotope composition (δ15N) in roots and stronger responsiveness of transcriptional regulation of 18 genes involved in N metabolism were found in roots and leaves of Pp compared to those of Pg. These results indicate that the N metabolism of Pp is more sensitive to decreasing N availability than that of Pg. In both species, low N treatments decreased net influxes of NH4 + and NO3 –, root NH4 + and foliar NO3 – content, root NR activities, total N concentration in roots and leaves, and transcript levels of most ammonium (AMTs) and nitrate (NRTs) transporter genes in leaves and genes involved in N assimilation in roots and leaves. Low N availability increased fine root surface area, foliar starch concentration, δ15N in roots and leaves, and transcript abundance of several AMTs (e.g. AMT1;2) and NRTs (e.g. NRT1;2 and NRT2;4B) in roots of both species. These data indicate that poplar species slow down processes of N acquisition and assimilation in acclimation to limiting N supply.
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Spodoptera frugiperda is a significant migratory invasive pest, identified as a serious threat to agricultural production and food security in China. However, to our knowledge, the effects of most ...host plants on the biological characteristics of S. frugiperda have not been well studied. To develop effective management strategies for S. frugiperda in its new invasive habitat, basic biological and ecological knowledge of this pest are crucial requirements. Here, we examined the effects of six cash crops maize, wheat, soybean, tomato, cotton and Chinese cabbage on the development, survival, fecundity of S. frugiperda by using the age-stage, two-sex life table. The preadult stage, adult preoviposition period and total preoviposition period of S. frugiperda were shortest on maize and wheat but were longest on tomato. Fecundity was greatest on maize and wheat but smallest on tomato. The highest intrinsic rate of increase, finite rate of increase, net reproductive rate and the shortest mean generation time were recorded on maize. This present study showed that S. frugiperda could cause great economic losses to these cash crops, which should attract the attention of agricultural management departments. Our findings provide useful information in predicting population dynamics and understanding the potential damage that could be incurred by S. frugiperda invasion.
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To investigate how N-fertilization affects the growth, carbon and nitrogen (N) physiology, and wood properties of poplars with contrasting growth characteristics, slow-growing (Populus popularis, Pp) ...and fast-growing (P. alba×P. glandulosa, Pg) poplar saplings were exposed to different N levels. Above-ground biomass, leaf area, photosynthetic rates (A), instantaneous photosynthetic nitrogen use efficiency (PNUE i), chlorophyll and foliar sugar concentrations were higher in Pg than in Pp. Foliar nitrate reductase (NR) activities and root glutamate synthase (GOGAT) activities were higher in Pg than in Pp as were the N amount and NUE of new shoots. Lignin contents and calorific values of Pg wood were less than that of Pp wood. N-fertilization reduced root biomass of Pg more than of Pp, but increased leaf biomass, leaf area, A, and PNUEi of Pg more than of Pp. Among 13 genes involved in the transport of ammonium or nitrate or in N assimilation, transcripts showed more pronounced changes to N-fertilization in Pg than in Pp. Increases in NR activities and N contents due to N-fertilization were larger in Pg than in Pp. In both species, N-fertilization resulted in lower calorific values as well as shorter and wider vessel elements/fibres. These results suggest that growth, carbon and N physiology, and wood properties are more sensitive to increasing N availability in fast-growing poplars than in slow-growing ones, which is probably due to prioritized resource allocation to the leaves and accelerated N physiological processes in fast-growing poplars under higher N levels.
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Maternal effects can reduce offspring susceptibility to predators by altering resource allocation to young and reproducing larger offspring. While the perception of predation risk can vary according ...to a prey's life stage, it is unclear whether maternally experienced intraguild predation (IGP) risk during different life stages influences the maternal effects of predatory insects. We investigated the influence of exposure to intraguild predators (
(Pallas) (Coleoptera: Coccinellidae)) during the larval and/or adult stages on reproductive decisions and offspring growth in
(Fabricius). Independent of the life stage, when
females experienced IGP risk, their body weight and fecundity decreased, but the proportion of trophic eggs produced increased. However, egg mass, egg clutch number, and egg clutch size were not influenced by the treatment. Next, when offspring encountered
, mothers experiencing IGP risk during the larval and/or adult stages could increase their offspring's weight. Moreover, offspring in IGP environments reached a similar size as those with no-IGP environments when mothers experienced IGP risk during the larval and/or adult stages. Overall,
larval and/or adult exposure to IGP risk had no influence on egg size, but increased offspring body size when faced with
. Additionally, mothers experiencing IGP risk during different life stages showed increased production of trophic eggs. Because IGP is frequently observed on
and favours relatively larger individuals, different stages of
express threat-sensitively to IGP risk; inducing maternal effects can be an adaptive survival strategy to defend against
.
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The invasive pest, Spodoptera frugiperda, commonly known as the fall armyworm (FAW), is a serious threat to food security in multiple countries worldwide. Insects’ antennal sensilla play a crucial ...role in perceiving plant odors and communication between male and female insects. This study aimed to examine the antennal morphology and sensilla variations on the antennae of FAW larvae and adults through scanning electron microscope analysis. The results revealed that third and fifth instar larval antennae possessed smell pores, sensilla pegs, and five types of antennal sensilla, namely sensilla trichodea, sensilla basiconica, sensilla chaetica, sensilla campaniform, and sensilla styloconicum, and the smell pores were first observed in Lepidoptera larvae. Furthermore, the size of sensilla in fifth instar larvae was significantly greater than those in third instar. On the adult antennae, there were smell pores and 12 types of sensilla identified: sensilla trichodea, sensilla basicaonica, sensilla auricillica, sensilla cavity, sensilla placodea, sensilla ligulate, Böhm’s bristles, sensilla chaetica, sensilla squamous, sensilla coeloconica, sensilla styloconicum, and sensilla uniporous peg. Notably, the sensilla cavity, sensilla placodea, sensilla ligulate, sensilla uniporous peg, and smell pores were first discovered in FAW adults. Compared with larvae, FAW adults have more types and amounts of sensilla. Additionally, we also discussed the possible functions of these antennal sensilla. This study provides valuable information for a comprehensive understanding of the type and function of antennal sensilla in FAW and assists in the development of novel pest control strategies, such as pest behavior control technology, for the prevention of this invasive pest.
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The pea aphid,
, is a major pest of legume crops, exhibiting distinct polymorphism in terms of wings and body color. We found that, under crowded conditions, the red morph
produced more winged ...offspring than the green morph. The signaling pathways involved in aphid wing determination, like insulin and ecdysone, also play important roles in regulating growth, development, and metabolism. Thus, here, we examined the association between the wing-producing ability and the growth rate, development time, reproductive capacity, and energy metabolism in these two color morphs. The growth rate of red morphs was significantly higher than that of green morphs, whereas green morphs produced more offspring during the first 6 days of the adult stage. Red morphs accumulated higher levels of glycogen and triglycerides and consumed more triglycerides during starvation; however, green aphids consumed more trehalose during food deprivation. Red aphids exhibited stronger starvation tolerance, possibly due to their higher triglyceride catabolic activity. Furthermore, the expression levels of genes involved in the insulin pathway, glycolysis, and lipolysis in red aphids were higher than those in green aphids. These results suggest that the wing-producing ability of the pea aphid may be associated with its growth and metabolism, which may be due to the shared regulatory signaling pathways.
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In nature, plants can contain variable nutrients depending upon the species, tissue, and developmental stage. Insect herbivores may regulate their nutrient intake behaviorally and physio- logically ...when encountering different foods. This study examined the nutritional regulation of the oriental armyworm,
, for the first time. In one experiment, we allowed the cater-pillars to choose between two nutritionally balanced but complementary diets. The caterpillars did not randomly consume the paired foods, but instead chose between the nutritionally balanced but complementary diets. This intake behavior was found to change with their developmental stages. Furthermore, the nutrient concentrations in food significantly impacted the insect's performance. In the other experiment, caterpillars were given one of eleven diets that reflected the different nutrient conditions in the field. The results showed that proteins were significantly associated with developmental time and fecundity. For example, by consuming protein-biased food, the caterpillars developed faster and produced more eggs. In contrast, carbohydrates were more strongly linked to lipid accumulation, and caterpillars accumulated more lipids when consuming the carbohydrate-biased food. Moreover, the caterpillars were also found to actively regulate their intake of proteins and carbohydrates based on food quality and to physiologically prepare for subsequent life stages. These findings enhance our understanding of how
feeds and responds to different nutritional environments in the field, which could have implications for managing insect herbivores in agricultural settings.
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Insects are sterol auxotrophs and typically obtain sterols from food. However, the sterol demand and metabolic capacity vary greatly among species, even for closely related species. The low survival ...of many insects on atypical sterols, such as cholestanol and cholestanone, raises the possibility of using sterol-modified plants to control insect herbivore pests. In this study, we evaluated two devastating migratory crop pests, Mythimna separata and Spodoptera frugiperda, in response to atypical sterols and explored the reasons that caused the divergences in sterol nutritional biology between them. Contrary to M. separata, S. frugiperda had unexpectedly high survival on cholestanone, and nearly 80% of the individuals pupated. Comparative studies, including insect response to multiple diets and larval body sterol/steroids analysis, were performed to explain their differences in cholestanone usage. Our results showed that, in comparison to M. separata, the superiority of S. frugiperda on cholestanone can be attributed to its higher efficiency of converting ketone into available stanol and its lower demand for sterols, which resulted in a better survival when cholesterol was unavailable. This research will help us to better understand insect sterol nutritional biology and the potential of using atypical sterols to control herbivorous insect pests.
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