Reconciling empirical interactions and species coexistence

Coexistence in ecological communities is governed largely by the nature and intensity of species interactions. Countless studies have proposed methods to infer these interactions from empirical data, yet models parameterised using such data often fail to recover observed coexistence patterns. Here, we propose a method to reconcile empirical parameterisations of community dynamics with species‐abundance data, ensuring that the predicted equilibrium is consistent with the observed abundance distribution. To illustrate the approach, we explore two case studies: an experimental freshwater algal community and a long‐term time series of displacement in an intertidal community. We demonstrate how our method helps recover observed coexistence patterns, capture the core dynamics of the system, and, in the latter case, predict the impacts of experimental extinctions. Collectively, these results demonstrate an intuitive approach for reconciling observed and empirical data, improving our ability to explore the links between species interactions and coexistence in natural systems.     

Development of highly nutritive culture media

Summary A highly nutritive culture medium (MGM-464) was developed for insect cell primary culture. The new medium consists of 6 inorganic salts, 4 organic acids, 21 amino acids, 3 sugars, 10 vitamins, and 8 other chemicals, including natural substances. The complete medium was generated by adding 20 ml fetal bovine serum to 100 ml MGM-464. The detail of the composition of the medium is given in a table, and the protocol to prepare the medium is described in the text. Among the 15 kinds of cultures made with MGM-464, embryonic cells from a walking stick and ovarian cells from the common white were subcultured more than 70 times, and embryonic cells of a chrysomelid beetle were subcultured more than 15 times. Other cultures could not be subcultured. However, embryonic cells from the commercial silkworm and a cockroach, ovarial cells from the commercial silkworm and a sphingid moth, nervous cells from the commercial silkworm and two sphingid moths, and cells from the dorsal vessel plus surrounding tissue of the commercial silkworm survived for several mo. The cells from the honeybee embryos, aphid embryos, and planthopper embryos were rather short-lived, and deteriorated after about 1 mo.     

Biodiversity of galling insects: historical, community and habitat effects in four neotropical savannas

Five hypotheses were tested to explain the pattern of galling insect species richness in four neotropical savanna physiognomies, 'canga ', 'campo sujo', 'cerrado' s. st., and 'cerradão', that occur in Minas Gerais, southeastern Brazil. We found 125 species of galling insects on 80 host plant species. The increase of plant species richness explained 35% of the variation in galling insect richness, corroborating the plant species richness hypothesis. Most of the galling species occurred on trees, followed by shrubs, and herbs. However, the difference in mean number of galls was only statistically significant between herbs and trees, corroborating partially the plant structural complexity hypothesis. A significant relationship was observed between galling species richness and density of herbs, and shrubs, corroborating partially the resource concentration hypothesis. Galling insect richness showed a negative correlation with magnesium, potassium, and zinc on soil, corroborating the soil fertility hypothesis. The content of magnesium, potassium, iron and CTC (T) explained 72% of the variation in galling insect richness. Plant family size positively influenced galling insect richness, corroborating the plant family size hypothesis. Overall, the results corroborate the hypothesis that predicts that habitat stress is the main factor generating the patterns of galling insect richness in Brazilian savannas.     

Influence of host log age and refuge from natural enemies on colonization and survival of Phoracantha semipunctata

The pine cone weevil, Pissodes validirostris Gyll. (Coleoptera: Curculionidae), attacks seed cones of most Eurasian pine species, except these of Swiss stone pine (Pinus cembra L.). Behavioural responses of adult weevils to cone volatile emissions of Swiss stone pine and to those of a common host, mountain pine (Pinus uncinata Ram.), were compared in an olfactometer. Weevils were significantly attracted by the volatile blend emitted by mountain pine, but Swiss stone pine volatiles elicited an inverse response, with most weevils moving in the opposite direction to the odour source. However, the majority of second instar weevil larvae that were extracted from mountain pine cones and transferred into Swiss stone pine cones were capable of developing to the adult stage. This suggests that Swiss stone pine cones do not contain strong feeding deterrents that could prevent larval development. The possible factors involved in the absence of colonization of Swiss stone pine cones by cone weevils are discussed.     

昆虫RNAi通路及其核心元件的研究综述

RNAi作为分子生物学的一种重要技术,在昆虫基因功能和功能基因组研究中得到广泛应用,同时,有关昆虫RNAi的机制也受到了大家的关注。近年来的研究结果表明,昆虫RNAi的通路与其他动物相同,根据引起基因沉默的RNA分子的类型,可以分为siRNA、miRNA和piRNA 3种不同的通路。昆虫RNAi通路中的核心元件包括了:(1)行使切割作用的RNaseⅢ家族成员Drosha和Dicer;(2)用来降解目的 mRNA的Argonaute蛋白;(3)dsRNA结合蛋白Pasha、R2D2和Loquacious。了解昆虫RNAi的通路及其核心元件,有助于我们更好地理解昆虫RNAi的分子机制和改进实现RNAi的方法,对促进昆虫RNAi技术的研究及其在害虫防控中的应用具有指导意义。     

In silico and bio assay of juvenile hormone analogs as an insect growth regulator against Galleria mellonella (wax moth) – Part I

Juvenile hormone (JH) analogs are nowadays in use to control harmful pests. In order to develop new bioactive molecules as potential pesticides, we have incorporated different active structural features like sulfonamide, aromatic rings, amide group, and amino acid moiety to the base structure. We have screened a series of designed novel JH analogs against JH receptor protein (jhbpGm-2RCK) of Galleria mellonella in comparison to commercial insect growth regulators (IGRs) – Pyriproxyfen (T₁) and Fenoxycarb (T₂). All analogs exhibit the binding energy profile comparable to commercial IGRs. Based upon these results, a series of sulfonamide-based JHAs (T₃–T₈) as IGRs have been synthesized and characterized. Further, the efficacy of synthesized analogs (T₃–T₈) and commercial IGRs (Pyriproxyfen and Fenoxycarb) has been assessed against fourth instars larvae of G. mellonella under the laboratory conditions. LC₅₀ values of all the analogs (T₁–T₈) against the fourth instars larvae were 9.99, 10.12, 24.76, 30.73, 38.45, 34.15, 34.14, 19.48 ppm and the LC₉₀ 153.27, 131.69, 112.15, 191.46, 427.02, 167.13, 217.10, 172.00 ppm, respectively. Among these analogs, N-(1-isopropyl-2-oxo-3-aza-3-N-ethyl-pentanyl)-p-toluene sulfonamide (T₈) and N-(1-isopropyl-2-oxo-3-aza-3-N-ethyl-pentanyl) benzene sulfonamide (T₇) exhibited the good pest larval mortality at different exposure periods (in hours) and different concentrations (in ppm) in comparison to in use IGRs- T₁ and T₂. Bio assay results are supported by docking at higher concentration. The present investigation clearly exhibits that analog T₈ could serve as a potential IGR in comparison to in use IGRs (T₁ and T₂). The results are promising and provide new array of synthetic chemicals that may be utilized as IGRs.     

花颜色和花气味的量化研究方法

花颜色和花气味是花部构成的重要内容。在已开展的传粉生态学研究中对二者的报道主要是描述性的,而其量化研究可以为揭示传粉机制提供有力的实验证据。本文主要介绍了花颜色的测量和标定方法,包括比色卡、分光色差仪和便携式光谱仪等;花气味的采集方法,包括动态顶空套袋-吸附采集法、吸附-溶剂洗脱法和固相微萃取法等;花气味的检测和分析方法,包括气相色谱-质谱联用仪分析和电子鼻型超速气相色谱仪分析等;以及昆虫行为学实验方法,包括气相色谱-昆虫触角电位联用技术、Y型嗅觉仪和飞行箱实验等。科研人员可以根据实验材料的特点和实验目的选择适合的量化研究方法。     

Vertical stratification of feeding guilds and body size in beetle assemblages from an Australian tropical rainforest

Abstract The vertical stratification of insect species assemblages inhabiting tropical rainforests is well established but few have examined whether these patterns are reflected in vertical stratification of body size or feeding guilds. We used Malaise and Flight Interception Traps to sample beetle assemblages from five locations, at both canopy and ground zones of a tropical lowland rainforest site near Cape Tribulation, Australia. Beetles from 4 years of sampling were sorted to Family and morphospecies, and allocated to one of five feeding guilds. Within feeding guilds the number of species and individuals, from canopy‐ and ground‐caught traps were compared. The body lengths of species were measure and compared within feeding guilds and families. Herbivores was the dominant guild but was not the majority of all species or individuals. Most beetle species (69%) were less than 5 mm in length and the mean size of canopy‐caught species was greater than that for ground‐caught species. This was probably due to slightly more species of plant feeders (herbivores and xylophages) present in the canopy, which were significantly larger than saprophages, fungivores and predators. Among feeding guilds, there were few overall canopy–ground differences. These results contrast with species composition results presented elsewhere where strong differences between the canopy and the ground were evident. We suggest that our guild groupings may have been too coarse to detect fine‐scale differences and that resource partitioning may have also masked faunal stratification. We propose that fine‐scale differences in resources between the canopy and the ground, together with strong microclimate gradients, are likely to be important in structuring the vertical stratification of insect assemblages at the level of species, but not with respect to functional groups.     

Potential effects of elevated carbon dioxide on leaf-feeding forest insects

The elevated concentration of atmospheric CO₂ may result in a decline of leaf nutritional quality (especially N) and an increase in some kinds of defensive secondary components (such as phenolics). The changes in the phytochemistry of trees, combined with the effect of elevated CO₂ per se, have a potential negative influence on insect herbivores. Here, we review the effect of elevated CO₂ on the performance of leaffeeding forest insects at individual-level and community-level. The elevated CO₂ per se have little influence on the metabolism of insects. Over half of the tree-insect experimental systems show that the performance of individual insect become poorer under high-CO₂ grown trees; but the others show that the insects have just little or no response to the treatments. The direction and magnitude of the changes in the performance of insects could be mediated by various factors. The effects of treatment are strongly species-dependent. The magnitude of changes in the phytochemistry, the sensitivity and adaptive capacity of insects to the poorer leaf quality, the differences in plant growth conditions and experimental methods, and the mediated effects of other environmental factors (such as soil nutrient availability, light, temperature, O₃) were all closely related to the final performance of insects. However, the larvae’s consumption usually increased under enriched CO₂ treatment, which was widely thought to be a compensatory response to poorer plant quality. The experiments on forest community-level found identically a reduction in herbivory, which was contrary to the results from small-scale experiments. The changes in insect population and the actual response of consumption by leaf-feeding forest insects under CO₂ enrichment remain unclear, and more field-based experiments need to be conducted. __________ Translated from Chinese Journal of Applied Ecology, 2006, 17(4): 720–726 [译自: 应用生态学报]     

Real‐time cell analysis and heat shock protein gene expression in the TcA Tribolium castaneum cell line in response to environmental stress conditions

The rust red flour beetle, Tribolium castaneum (Herbst, 1797) (Coleoptera: Tenebrionidae), is a pest of stored grain and one of the most studied insect model species. Some of the previous studies involved heat response studies in terms of survival and heat shock protein expression, which are regulated to protect other proteins against environmental stress conditions. In the present study, we characterize the impedance profile with the xCELLigence Real‐Time Cell Analyzer and study the effect of increased temperature in cell growth and viability in the cell line BCIRL‐TcA‐CLG1 (TcA) of T. castaneum. This novel system measures cells behavior in real time and is applied for the first time to insect cells. Additionally, cells are exposed to heat shock, increased salinity, acidic pH and UV‐A light with the aim of measuring the expression levels of Hsp27, Hsp68a, and Hsp83 genes. Results show a high thermotolerance of TcA in terms of cell growth and viability. This result is likely related to gene expression results in which a significant up‐regulation of all studied Hsp genes is observed after 1 h of exposure to 40 °C and UV light. All 3 genes show similar expression patterns, but Hsp27 seems to be the most affected. The results of this study validate the RTCA method and reveal the utility of insect cell lines, real‐time analysis and gene expression studies to better understand the physiological response of insect cells, with potential applications in different fields of biology such as conservation biology and pest management.