The endoparasitoid Psyllaephagus arenarius benefits from ectoparasitic venom via multiparasitism with the ectoparasitoid Tamarixia lyciumi

As solitary nymphal parasitoids of Paratrioza sinica, the ectoparasitoid Tamarixia lyciumi and the endoparasitoid Psyllaephagus arenarius act as effective biocontrol agents. Thus, it is necessary to facilitate mass productions of both species. Despite showing an excellent parasitic ability, Ps. arenarius is often trapped fatally inside 5th‐instar nymphs of Pa. sinica due to strong host immunity. To improve the emergence rate of Ps. arenarius, we evaluated whether Ps. arenarius could utilize T. lyciumi venom via multiparasitism, so the parasitism characteristics of both species were examined between separate‐existence (monoparasitism only) and co‐existence (mono‐ and multiparasitism) systems. Further, the parasitism characteristics of Ps. arenarius on venom‐injected hosts with/without T. lyciumi eggs were tested to further identify the facilitator. The results showed the parasitism rate of T. lyciumi was increased while that of Ps. arenarius did not change from separate‐existence to co‐existence systems. The intrinsic performances of two species in monoparasitism did not differ between separate‐ and co‐existence systems. From monoparasitism (separate‐existence) to multiparasitism (co‐existence), no differences were detected in the intrinsic performances of T. lyciumi, but those of Ps. arenarius were greatly improved. After T. lyciumi venom injection, the parasitism characteristics of Ps. arenarius did not differ between venom‐injected hosts with T. lyciumi eggs and those without, further indicating Ps. arenarius benefited from the venom of T. lyciumi females rather than T. lyciumi egg/larval secretions. Instead of negative effects, multiparasitism with ectoparasitoids improves endoparasitoids due to ectoparasitic venom. The study increases host resource utilization and provides creative ways for mass production of endoparasitoids.     

Functional response and mutual interference of Peristenus spretus (Hymenoptera: Braconidae), a parasitoid of Apolygus lucorum (Heteroptera: Miridae)

Peristenus spretus Chen & van Achterberg (Hymenoptera: Braconidae) is a solitary endoparasitoid, which is considered for augmentative biological control of Apolygus lucorum Meyer-Dür (Heteroptera: Miridae) in Chinese cotton fields. Since the association of P. spretus with A. lucorum was only recently discovered, the biology of the parasitoid remains unknown. In order to understand its reproductive biology, the mutual interference and functional response of P. spretus were investigated by altering either the parasitoid or the host density while keeping the other constant. In both experiments, the effects of parasitoid and host densities on parasitism, superparasitism, progeny production and sex ratio were assessed. P. spretus exhibited a Holling type II functional response to changing host densities, indicating that parasitism increases with increasing host density until the parasitoid reaches its maximum reproductive capacity. The model suggested that a single P. spretus female could parasitise a maximum of 88 nymphs per day or four nymphs per hour. Increasing the wasp-nymph ratio from 1:10 to 1:80 significantly increased the offspring production more than fivefold from ±5.8 to ±35.6; further increasing the host densities (above 80 nymphs) did not significantly increase offspring production. Strong mutual interference of foraging P. spretus females occurred only at high parasitoid densities. Parasitoids foraging alone produced an average progeny of 33.4, whereas parasitoids foraging in groups of 16 produced only 2.6. The optimal wasp-nymph ratio for mass-rearing P. spretus is 4:100, given that resources of parasitoids and nymphs are unlimited.     

Development and application of a rapid and efficient CZE method coupled with correction factors for determination of monosaccharide composition of acidic hetero-polysaccharides from Ephedra sinica

Introduction – Ephedrine alkaloids cannot account for all the effects of Ephedra sinica and the polysaccharides are also demonstrated to be one of the main bioactive constituents of E. sinica. However, no work has been reported on the analysis of monosaccharide composition of purified polysaccharides isolated from the stem of E. sinica. Objective – To develop a rapid and efficient capillary zone electrophoresis (CZE) method based on pre‐column derivatisation with 1‐phenyl‐3‐methyl‐5‐pyrazolone for the simultaneous determination of neutral and acidic sugars of purified polysaccharides from E. sinica. Methodology – Three polysaccharides (ESP‐A3, ESP‐A4 and ESP‐B4) were isolated and purified by ion exchange and gel‐filtration chromatography from the stem of E. sinica. The effects of background electrolyte pH and concentration, applied voltage and temperature on the separation were investigated. Meanwhile, factors affecting the hydrolysis of ESP‐B4 with sulphuric acid were investigated by changing the hydrolysis time, acid concentration and hydrolytic temperature to achieve complete hydrolysis. The standard curves coupled with correction factors were used to calculate molar ratios. Results – The optimal CZE method coupled with correction factors was successfully applied to the determination of molar ratios of three purified polysaccharides and their corresponding partial acid hydrolysis products. ESP‐A3, ESP‐A4 and ESP‐B4 were all typical acidic hetero‐polysaccharides and consisted of xylose, arabinose, glucose, rhamnose, mannose, galactose, glucuronic acid and galacturonic acid, and their corresponding molar ratios were 6.8:7.5:1.0:14.0:13.7:22.3:10.2:3.8 for ESP‐A3, 1.2:4.1:1.0:5.1:1.6:17.3:3.1:2.2 for ESP‐A4, and 1.0:4.5:1.0:2.0:1.0:5.5:1.5:50.0 for ESP‐B4. Conclusion – The results provided scientific evidence for the further study of the structure and bioactivity of complex acidic E. sinica polysaccharides. Copyright © 2010 John Wiley & Sons, Ltd.     

Energy budgets of the Chinese green lacewing （Neuroptera： Chrysopidae） and its potential for biological control of the cotton aphid （Homoptera： Aphididae）

Energy budgets of larval stages of the Chinese green lacewing, Chrysopa sinica (Tjeder) (Neuroptera: Chrysopidae) were determined under laboratory conditions at photo‐period of 14:10 L:D, 27 ± 1°C and 75%± 2% RH. The energy used as ingestion, assimilation, respiration, productivity and feces was constructed for each developmental stage. In addition, under these experimental conditions, the potential of C. sinica as a biological control agent was evaluated according to the ingestion by this predator and the energy content of cotton aphid, Aphis gossypii (Glover) (Homoptera: Aphididae). The larval stage of C. sinica was able to consume 1281.4 1‐day‐old aphids, 1018.7 2‐day‐old aphids, 626.9 3‐day‐old aphids, 393.5 4‐day‐old aphids, 312.1 5‐day‐old aphids or 203.5 9‐day‐old aphids, respectively. No significant difference was detected between the estimated number of aphids consumed by the lacewings using energetic methods and the actual number of aphids consumed by the lacewings in this experiment. Our results showed that C. sinica is an important natural enemy of the cotton aphid, and energetic methods are very useful to quantify biological control efficacy of natural enemies.     

Effect of mating combinations on the host parasitisation and sex allocation in solitary endoparasitoid,Aenasius arizonensis (Hymenoptera: Encyrtidae)

Aenasius arizonensis (Girault) is an important solitary endoparasitoid of Phenacoccus solenopsis Tinsley. To optimise the mass production of high-quality females, it is important to assess the influence of mating regimes on the progeny fitness and sex allocation. We, therefore, hypothesise that mating combinations in A. arizonensis adults emerged from different host instars may influence parasitism and sex allocation in the subsequent generation. Therefore, we compared three nymphal instars (1st, 2nd and 3rd) and adults host stages of P. solenopsis for parasitism and sex allocation by A. arizonensis. Further, F₁ female progeny of the parasitoid emerged from different host instars was henceforth evaluated for its fitness in six mating combinations. A. arizonensis females parasitised all the host stages except the 1st instar nymphs. The parasitised 2nd instar nymphs yielded only males, while the sex ratio in the later host instars was strongly female-biased. The parasitoid females preferred 3rd instar nymphs with respect to higher parasitism (74.0–84.0%) and produced more females in the F₁ progeny as compared to other host stages. F₁ females that emerged from 3rd instar nymphs produced significantly higher parasitism (74.0–79.0%). These mating combinations also yielded more female progeny in the F₂ generation. However, parasitism by F₁ females was significantly lower (9.0–12.0%) when mated with males that emerged from 2nd instar P. solenopsis nymphs. Moreover, latter combinations yielded only male progeny in F₂ generation. These findings can be used in laboratory mass rearing of this parasitoid vis-à-vis biological control of P. solenopsis.     

Chemical aspects of host‐acceptance behaviour in the bird cherry‐oat aphid Rhopalosiphum padi: host‐acceptance signals used by different morphs with the same genotype

Host acceptance by gynoparae and winged virginoparae of the bird cherry‐oat aphid Rhopalosiphum padi (L.) is investigated utilizing leaves and aqueous extracts of the primary and secondary hosts, as well as nonhost plants. Gynoparae are specialized to reproduce on bird cherry Prunus padus L., whereas virginoparae reproduce and feed on various grasses. Host acceptance is assessed using levels of reproduction and survival for adults, as well as survival for nymphs. Little is known of host acceptance by nymphs. The data show that gynoparae and winged virginoparae produce nymphs almost exclusively on their host plants, bird cherry and barley leaves, respectively, over 72 h. When tested with aqueous plant extracts, however, gynoparae produce nymphs almost exclusively on bird cherry extract and progeny numbers are found to be similar to those on plant leaves. Few nymphs are produced on artificial diet. By contrast, winged virginoparae produce nymphs on aqueous extracts of barley, bird cherry and bean, as well as on artificial diet. The numbers of nymphs deposited by gynoparae are similar on aqueous extracts of bird cherry leaves collected at different times during the growing season. When extracts from leaves of various Prunus species are tested, only leaves of P. padus and Prunus virginiana stimulate parturition. Oviparae, the sexual female nymphs of gynoparae, survive well for 96 h on both bird cherry and barley leaves but not on bean seedlings, whereas nymphs of winged virginoparae survive well only on barley leaves. They do not survive for 96 h on any plant‐leaf extracts, although they do survive on artificial diet.     

Patch Time Allocation by the Parasitoid Diadegma semiclausum (Hymenoptera: Ichneumonidae). III. Effects of Kairomone Sources and Previous Parasitism

We investigated the effects of kairomone sources and previous parasitism on the patch-leaving behavior of Diadegma semiclausum, a solitary endoparasitoid of larval Plutella xylostella. Individual female wasps were released onto an experimental plant, and were allowed to freely leave for an alternative host plant placed upwind of the experimental plant in a wind tunnel. In one experiment, the experimental plant was either intact, contained host damage alone, or contained both hosts and host damage. In another experiment, the plant was infested with either unparasitized hosts, hosts parasitized previously by the female herself, or parasitized by Cotesia plutellae, another larval endoparasitoid of P. xylostella. We analyzed the influence of kairomone sources, host types, and within-patch foraging experience on the patch-leaving tendency of D. semiclausum by means of the proportional hazards model. Presence of host damage, and unsuccessful host encounters as a result of host defenses decreased the parasitoids' patch-leaving tendency, while successful oviposition, self-superparasitism, and rejection of parasitized hosts increased their patch-leaving tendency. A conceptual model of the parasitoid's patch-leaving behavior is proposed on the basis of the results of current and previous studies.     

The feeding behaviour of the Cambrian tubiculous priapulid Selkirkia

Feeding behavioural patterns have the potential to shed light on evolutionary trends, especially at the critical point of the Cambrian Explosion. In this context, we present specimens of the tubiform priapulid Selkirkia sinica, preserved in situ, collected from the lower Cambrian (Stage 3) Xiaoshiba Lagerstätte, which show the diverse morphology of its intestinal contents within the dark‐coloured gut and the formation of faecal pellets. The two digestive modes displayed by S. sinica suggest that it is a putative dietary generalist rather than a typical scavenger as previously thought. Moreover, the asymmetry exhibited by the paired caudal appendages of S. sinica provides direct evidence of the development of dorsoventral (DV) differentiation in Selkirkia, which aids our understanding of the lifestyle of this tubiculous worm.     

Substrate relations of the African wood‐burrowing mayfly Povilla adusta Navás (Ephemeroptera,Polymitarcyidae)

Colonization of an artificial substrate (polyurethane foam) by nymphs of the wood‐burrowing mayfly Povilla adusta was studied in a natural West‐African lake (Opi Lake). Nymphs readily colonized the substrate in densities up to 11,000 m^‐2 (early instars) and at depths ≤ 1.5 m. Blocks with rough surfaces and those in close proximity to oviposition sites near‐shore, had larger densities of nymphs than did those with smooth surfaces or those placed off‐shore. The upper surfaces of submerged blocks had smaller numbers of larger nymphs than did lower surfaces. Differences in the abundance of periphyton on the various surfaces may account for some of these patterns. The generation time of P. adusta is estimated to be three months in Opi Lake.     

Elevated CO2 lessens predation of Chrysopa sinica on Aphis gossypii

Most studies on the effects of elevated atmospheric CO₂ on organisms have focused on the performance of plants or herbivores. Few reports have examined the impact on the ability of predators at the third trophic level. In this experiment, we made use of open‐top chambers to quantify the effects of elevated CO₂ on growth, development, and predatory ability of two successive generations of Chinese lacewing, Chrysopa sinica (Tjeder) (Neuroptera: Chrysopidae), feeding on cotton aphids, Aphis gossypii (Glover) (Hemiptera: Aphididae), which were reared on cotton, Gossypium hirsutum L. (Malvaceae), grown under elevated CO₂ (double ambient vs. ambient). Higher atmospheric CO₂ concentrations reduced the duration of larval development and the survival rate of pupae, and caused decreased weight in adult female C. sinica, but had no significant effects on survival rate of each larval stage, female adult fecundity, egg hatch rate, or adult life span. The predatory ability of larvae in the third instar and the total larval stage of C. sinica that fed on A. gossypii were significantly lower in elevated CO₂ environments. The number of aphids consumed by first‐generation lacewing population did not change significantly with different CO₂ treatments; however, significantly fewer aphids were consumed by the second generation of the lacewing population with elevated CO₂. We speculate that A. gossypii may become a more serious pest under an environment with elevated CO₂ concentrations because of the reduced predatory ability of C. sinica on A. gossypii.     

Effect of host deprivation on the foraging behavior of the Asian citrus psyllid parasitoid Tamarixia radiata: observations from the laboratory and the field

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a significant citrus pest and the parasitoid Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) has been released in various citrus‐producing areas in classical biological control programs targeting D. citri. We investigated the effect of host deprivation on the foraging behavior and patch utilization by T. radiata. In the laboratory, females deprived of hosts for 3 days tended to leave patches of 12 nymphs without parasitizing hosts during the ca. 30 min they spent in the patch before leaving. Moreover, half of these females failed to host feed, and those that did host feed, on average, needed more than 15 min to complete feeding. Conversely, non‐host‐deprived females parasitized on average three nymphs before leaving patches without host feeding during the ca. 39 min they spent in the patch. These laboratory observations were compared to mass‐reared female T. radiata that were released onto colonies of D. citri nymphs infesting citrus in the field. Release vials were provisioned with honey and these females had no opportunities to host feed over the 1‐ to 2‐day containment period prior to release. When introduced onto D. citri colonies, 68% T. radiata females abandoned D. citri patches prior to probing hosts, in part, because Argentine ants, Linepithema humile (Mayr) (Hymenoptera: Formicidae), tending colonies disturbed searching parasitoids. These results from laboratory and field studies are discussed in the context of classical biological control, with the aim of understanding how to manipulate host availability and ant activity so establishment rates and impact of T. radiata can be improved.     

Structural and Functional Grounds for Ephedra sinica Expansion in Mongolian Steppe Ecosystems

Morphological and structural characteristics of photosynthetic organs, diurnal changes in photosynthetic and transpiration rates, and the efficiency of water use were studied in three plant species from mountain-steppe ecosystems in Mongolia, Ephedra sinica Stapf, Stipa glareosa P. Smirn., and Allium polyrhizum Furcz. ex Regel. The species studied differed in the structural and functional mechanisms for the adaptation of photosynthetic apparatus to arid conditions. E. sinica has thick, vertical assimilating shoots, which are characterized by a high density (620 mg/cm³) and a small proportion of photosynthetic tissues (13%). The proportion of meso-phyll in the leaves of A. polyrhizum and S. glareosa was two and three times higher, respectively. The low content of phototrophic tissues in E. sinica shoot was compensated for by a high photosynthetic activity of single chloroplasts (25 mg CO₂/(10⁹ chloroplast h)), which was six times higher, than in two other species. Daily course of photosynthesis and transpiration inE. sinica differed from those of A. polyrhizum and S. glareosa by the absence of the midday depression. E. sinica had the highest efficiency of water use (45 mg CO₂/g H₂O) due to a low transpiration rate (0.25 g/g fr wt h). It is concluded that, in E. sinica, the main strategy for adaptation to arid stress is to develop in the shoot a few photosynthesizing cells of high assimilation activity. Such structural organization of photosynthetic organs in ephedra contributes to its higher efficiency of water use and stability of physiological characteristics under changing environmental conditions. These specific features of the structure of assimilating organs and their functional features contribute to a greater expansion of E. sinica with increasing climate aridization in Mongolia.     

Functional analysis of two polygalacturonase genes in Apolygus lucorum associated with eliciting plant injury using RNA interference

Salivary enzymes of many piercing–sucking insects lead to host plant injury. The salivary enzymes, polygalacturonase (PGs), act in insect feeding. PG family genes have been cloned from the mirid bug Apolygus lucorum, a pest of cotton and other host crops in China. We investigated the function of two PG genes that are highly expressed in A. lucorum nymphs (PG3‐4) and adults (PG3‐5), using siRNA injection‐based RNA interference (RNAi). Accumulation of mRNA encoding both genes and their cognate proteins was significantly reduced (>60%) in experimental compared control green fluorescent protein (GFP) siRNA‐treated mirids at 48 h post injection. Injury levels of cotton buds were also significantly reduced after injecting saliva isolated from PG3‐4 and PG3‐5 siRNA‐treated A. lucorum. These results demonstrate that these two PG act in A. lucorum elicitation of plant injury.     

基于LC-MS代谢组学技术的丽豆-大豆差异代谢物比较研究

丽豆(Calophaca sinica)是我国华北地区特有的一种珍稀野生植物。为探明丽豆的营养价值，该文以大豆(Glycine max)为参照组，利用液相色谱-质谱联用(LC-MS)技术对其种子进行了比较代谢组学研究。结果表明：(1)丽豆和大豆中共检测到1 857种代谢产物，二者成分相同且含量相似的代谢物有1 698种(>90%),差异代谢物有159种(<10%)。(2)在差异代谢物中，成分差异的有9种，其中有5种为丽豆特有，剩余150种均为含量差异，其中48种(约30%)在丽豆中的含量高于大豆。(3) KEGG注释到8条差异代谢物显著富集(P<0.1)的通路，主要包括初生代谢物的各类氨基酸生物合成途径和次生代谢物的罗汉松脂素、花生四烯酸以及二萜类等生物合成途径。(4)丽豆比大豆含量低的化学组分主要是初生代谢产物，比大豆含量高的化学组分主要是次生代谢物，而这些次生代谢物在调节血糖、骨坏损修复、增强免疫以及消炎抗癌等生理过程中有着积极的作用。综上所述，该研究认为丽豆与大豆具有相近的营养价值，并且对改善人类亚健康状况有积极的影响；此外，该文使我们对丽豆的营养价值和代谢组成...     

Temporal pattern of floral color change and time retention of post‐change flowers in Weigela japonica var. sinica (Caprifoliaceae)

Abstract Floral color changes are common in Weigela and the retention of post‐change flowers has been interpreted as a mechanism to increase attractiveness from a long distance and shorten pollinators’ lingering time on the inflorescence(s) of individual plants. In the present study, we investigated the temporal pattern of floral color change and time required for pollen tube growth in the shrub Weigela japonica var. sinica. Over the 4‐day anthesis, the color of the corolla in this species changes from white to red and the color cue changes from yellow to purple. The duration of both the white phase and the intermediate phase is approximately 1 day and the duration of the red phase is approximately 2 days. Our studies showed that color change in Weigela japonica var. sinica is age‐dependent but independent of pollinator visits and flower pollination. Post‐change flowers lost most of both the male and female residual reproductive ability and retained no rewards for pollinators. It took at least 3 days for a pollen tube to grow to the ovules and achieve fertilization. Thus, retention of post‐change flowers is necessary for the completion of pollen tube growth. Our results indicate that the temporal pattern of color change and time requirement for pollen tube growth are most likely related events.     

Life‐history parameters and predation capacity of Macrolophus pygmaeus and Nesidiocoris tenuis (Hemiptera: Miridae) on eggs of Plutella xylostella (Lepidoptera: Plutellidae)

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Nerium oleander as an alternative host plant for south Florida milkweed bugs, Oncopeltus fasciatus

Abstract.

• 1 Life history data were gathered for south Florida Oncopeltus fasciatus reared from eggs on Nerium oleander seeds and milkweed seeds in the laboratory.
• 2 Milkweed seeds were found to be a superior food source since O.fasciatus grew faster, laid more clutches, and has a higher total fecundity on milkweed seeds.
• 3 Fruiting N.oleander was found to be a better food source than nonfruiting milkweeds in a summer field study in south Florida since no nymphs survived to the adult stage on nonfruiting milkweeds but some did on N.oleander.
• 4 O.fasciatus adults and nymphs are abundant on N.oleander in the summer in south Florida when N.oleander is fruiting; no O.fasciatus nymphs are found in the summer on the milkweeds which are not fruiting.
• 5 O.fasciatus leave N.oleander in the autumn when milkweeds start to fruit and can then be found on fruiting milkweeds.

     

Control of experimental Triatoma infestans populations: effect of pour‐on cypermethrin applied to chickens under natural conditions in the Argentinean Chaco region

Among peridomestic structures, chicken coops are sites of major importance for the domestic ecology of Triatoma infestans (Hemiptera: Reduviidae). The aim of this study was to evaluate in an experimental context the effects of a cypermethrin pour‐on formulation applied to chickens on blood intake, moulting and mortality in T. infestans, under the natural climatic conditions of a region endemic for Chagas' disease. Experimental chicken huts were made of bricks and covered with plastic mosquito nets. Ninety fourth‐instar nymphs were maintained in each hut. The study used a completely random design in which chickens in the experimental group were treated with a cypermethrin pour‐on formulation. Five replicates (= huts) of the experimental and control groups were conducted. The number of live T. infestans, blood intake and moults to fifth‐instar stage were recorded at 1, 5, 20, 35 and 45 days after the application of cypermethrin. Cumulative mortality was higher in nymphs exposed to treated chickens (> 71%) than in control nymphs (< 50%) (P < 0.01). Blood intake and moulting rate were lower in nymphs fed on treated chickens than in control nymphs (P < 0.05). Pour‐on cypermethrin was able to cause significant mortality, although it did not eliminate the experimental population of T. infestans.