A review of myrmecophily in ant nest beetles (Coleoptera: Carabidae: Paussinae): linking early observations with recent findings

Myrmecophily provides various examples of how social structures can be overcome to exploit vast and well-protected resources. Ant nest beetles (Paussinae) are particularly well suited for ecological and evolutionary considerations in the context of association with ants because life habits within the subfamily range from free-living and predatory in basal taxa to obligatory myrmecophily in derived Paussini. Adult Paussini are accepted in the ant society, although parasitising the colony by preying on ant brood. Host species mainly belong to the ant families Myrmicinae and Formicinae, but at least several paussine genera are not host-specific. Morphological adaptations, such as special glands and associated tufts of hair (trichomes), characterise Paussini as typical myrmecophiles and lead to two different strategical types of body shape: while certain Paussini rely on the protective type with less exposed extremities, other genera access ant colonies using glandular secretions and trichomes (symphile type). We compare these adaptations with other taxonomic groups of insects by joining contemporary research and early sources and discuss the possibility of an attracting or appeasing effect of the secretion. Species that are ignored by their host ants might use chemical mimicry instead. Furthermore, vibrational signals may contribute to ant–beetle communication, and chemical signals have proven to play a role in host finding. The powerful defense chemistry of paussines as “bombardier beetles” is not used in contact with host ants. We attempt to trace the evolution of myrmecophily in paussines by reviewing important aspects of the association between paussine beetles and ants, i.e. morphological and potential chemical adaptations, life cycle, host specificity, alimentation, parasitism and sound production.

An estimated 400–800 million tons of prey are annually killed by the global spider community

Spiders have been suspected to be one of the most important groups of natural enemies of insects worldwide. To document the impact of the global spider community as insect predators, we present estimates of the biomass of annually killed insect prey. Our estimates assessed with two different methods suggest that the annual prey kill of the global spider community is in the range of 400–800 million metric tons (fresh weight), with insects and collembolans composing >90% of the captured prey. This equals approximately 1‰ of the global terrestrial net primary production. Spiders associated with forests and grasslands account for >95% of the annual prey kill of the global spider community, whereas spiders in other habitats are rather insignificant contributors over a full year. The spider communities associated with annual crops contribute less than 2% to the global annual prey kill. This, however, can be partly explained by the fact that annual crop fields are “disturbed habitats” with a low buildup of spider biomass and that agrobiont spiders often only kill prey over short time periods in a year. Our estimates are supported by the published results of exclusion experiments, showing that the number of herbivorous/detritivorous insects and collembolans increased significantly after spider removal from experimental plots. The presented estimates of the global annual prey kill and the relative contribution of spider predation in different biomes improve the general understanding of spider ecology and provide a first assessment of the global impact of this very important predator group.     

Testing the influence of gravity on flower symmetry in five <Emphasis Type="Italic">Saxifraga</Emphasis> species

Flower symmetry is considered a species-specific trait and is categorized in asymmetry, actinomorphic symmetry, bisymmetry and zygomorphic symmetry. Here we report on the intra-individual variation of flower symmetry in the genus Saxifraga and the influence of light, gravity and intrinsic factors on the development of flower symmetry. We tested five species—Saxifraga cuneifolia, Saxifraga imparilis, Saxifraga rotundifolia, Saxifraga stolonifera and Saxifraga umbrosa—concerning six flower parameters—angles between petals, petal length, petal pigmentation, angular position of carpels, movement of stamens and (only for S. imparilis and S. stolonifera) the length of the two lower elongated petals in regard to their position towards the stem. Specimens of all species were tested on a vertical clinostat as a gravity compensator, on a horizontal clinostat as a light incidence compensator and on a stationary control. The results show that the angle of incident light has no apparent impact on flower symmetry, whereas gravity affects the angular position of petals in S. cuneifolia and S. umbrosa and the petal colouration in S. rotundifolia. In S. cuneifolia and S. umbrosa, the absence of directional gravity resulted in the development of actinomorphic flowers, whereas the corresponding control flowers were zygomorphic. The development of flowers in S. rotundifolia was not altered by this treatment. The length of the two elongated petals in S. stolonifera and S. imparilis was not affected by gravity, but rather was determined by position of the flower within the inflorescence and resulted in asymmetrical flowers.     

生态旅游的机遇

对于许多人来说 , 生态旅游是一个 " 术语 " . 它是一个经常被误用或误解的词 . 正如这期 < 产业与环境 > 特刊中一些文章的作者所指出的那样 , 对生态旅游的定义仍在发展变化 . 但是 , 生态旅游总的目标应该是为发展旅游业同时把其负面影响降到最小提供一个机遇 . 生态旅 游作为一种可持续旅游手段 , 可以在与当地居民分享经济利益的同时避免环境的恶化 .     

Die Umsetzung des EU Weißbuches zur Chemikalienpolitik

Background

Aim and Scope. Implementation of the European Union White Paper on chemicals policy shall provide more safety and more transparency in chemicals use. In the past, when assessing existing commercial substances there was often a lack of information in the fields of application of the chemicals and the exposures arising in those contexts. The White Paper therefore calls for ‘shared responsibility’. Processors and commercial users of substances are to be involved much more closely in the risk evaluation process than has hitherto been the case. They are to provide data on substance applications and exposures, and, to some extent, they are also to carry out exposure assessments and risk assessments themselves. By analysing case studies, the paper highlights the consequences of this approach.

Results and Discussion

Fear has often been voiced that these new tasks will completely overburden small and medium-sized enterprises. It is assumed that many chemicals are no longer available for smallvolume applications, as — for cost reasons — producers do not include these applications in their registration. The wording of the White Paper is not precise enough to be able to appraise the costs that will be associated with the required intensified communication. In this situation, it is essential to analyse prototypical substances and their applications in order to gain an improved understanding of the principle of shared responsibility.

Conclusions

The concrete study of several product chains has shown that the flow of information required between producers and users is very likely feasible within the context of the REACH system. For the producers of chemicals, the intensified communication will presumably make it simpler to procure information in the fields of application and exposures. However, in order to avoid users being overburdened, it will be important that registration requirements and focuses are shaped in a manner doing justice to practical realities. Users will need to undertake community-wide efforts on an industry federation and branch level. In this context, the protection of company know-how also needs to be ensured.

Recommendation and Outlook

In practice, implementation of the principle of shared responsibility can lead to intensified communication among the producers and users of chemicals. This can greatly facilitate exposure assessments and risk assessments. There is a need to develop manageable procedures that can also be implemented by small and medium-sized enterprises. Numerous proposals have been made in this context, and extensive reference material is now available.     

Chemische Reaktionen von Chlorvinylarsinverbindungen (Lewisit)

2,2′-Dichlorodivinylarsine chloride (Lewisite II) react by room temperature quickly with alcohols in an equilibrium reaction to yield 2,2′-Dichlorodivinylarsine ether. The reactions are not quantitative. The methyl-, ethyl-and propylether are not stable.     

Paternal investment in Poecilimon veluchianus bushcrickets: beneficial effects of nuptial feeding on offspring viability

In most bushcrickets, males transfer a large spermatophore during copulation that is afterwards consumed by the female. In some species this nuptial gift enhances offspring fitness and is therefore believed to function as paternal investment. To determine whether this is the case, I examined whether a male's own offspring benefit from spermatophore consumption in the bushcricket Poecilimon veluchianus. Females that consumed a spermatophore produced offspring with increased residuals of dry weight compared to females that were prevented from feeding on the spermatophore. This beneficial effect of spermatophore consumption occurred within the first 4 days after copulation. An increased dry weight indicates higher energy reserves because offspring dry weight correlates significantly with the lifespan of starved larvae and because spermatophore consumption increased the lifespan of starved offspring. During egg-laying, females apply a liquid substance to the soil that hardens and probably serves as protection for the egg clutch. The amount of this substance correlated with the number of eggs laid but did not differ between spermatophore treatments. In P. veluchianus, females mate frequently and there is last-male sperm precedence. The spermatophore thus only constitutes paternal investment when offspring produced before female remating benefit from spermatophore consumption. The dry weight of offspring increased during the first 4 days after spermatophore consumption and thus within the natural remating interval. This shows that the spermatophore has a paternal investment function in addition to its already known sperm protection function. Received: 15 May 1998 / Accepted after revision: 11 October 1998     

Comparison of tarsal and cuticular chemistry in the leaf beetle Gastrophysa viridula (Coleoptera: Chrysomelidae) and an evaluation of solid-phase microextraction and solvent extraction techniques

Tarsal substrate adhesion in insects is based on the effect of a thin film of liquid in the contact zone, which is deposited as droplets on the surface an insect has walked on, but as yet, little is known about the chemical composition of the liquid. In the present study, interference reflection microscopical images of the tarsal contact and footprints of Gastrophysa viridula (Coleoptera: Chrysomelidae) are depicted and the chemical composition of tarsal liquids and cuticular components are investigated by means of solid-phase microextraction and solvent extraction of whole beetles and footprints. Based on this comparative methodical approach, we are first to provide evidence from direct sampling for the chemical congruence of cuticular lipids and tarsal liquid in beetles. Furthermore, differences resulting from the applied sampling techniques are assessed and advantages of the respective methods are discussed.     

Toxikologische Bewertung von Rüstungsaltlasten

A method was developed for the risk assessment of a military waste site. The method consists of two steps: 1. evaluation of the exposure through different pathways and 2. derivation of substance-specific tolerable intake levels. In this first part of the paper the quantitative exposure analysis will be discussed. Exposure depends on the conditions at the contaminated site (e.g. soil characteristics), the type of utilisation (residential area, industrial area etc.) and the substance properties. In a specific utilisation scenario, e.g. as residential area, different exposure pathways are contributing to the total contaminant uptake. Because of the properties of nitroaromatic compounds like 2,4,6-trinitrotoluene (good resorption through skin and accumulation in plants) exposure via dermal soil contact and via consumption of plants gains special importance. With these two exposure pathways as examples we explain the quantification of the exposure through different pathways by so-called exposure factors. By comparing the total exposure with tolerable intake levels for the compounds, waste site specific soil pollutant levels can be established (see second part of the paper in UWSF 6/94).     

Freisetzung von Schwermetallen aus dem bodenbildenden Tonmineral Illit durch Aminosäuren

Kaolin W from Lohrheim (51% Illite, 31% Kaolinite, 18% Quarz, no Carbon) was loaded with various amounts of heavy metal ions (0.11–6.0 mmol/100g Cu, Ni, Cd) from their nitrate solutions. In the next step the release of the bound metals was tested with or without aminoacids (penicillamine and histidine) in solutions of weak acidity or alkalinity. It was found an evident influence of the aminoacids to the metal release in dependence of metalcoating, metal-aminoacid-ratio and experimental pH. Especially in alkali environment a multiplication of the copper release (to a factor of 39 (pen) or 27 (his)) was observed. An increased nickel (factor 53) and cadmium release (factor 4.5) was found with histidine. In this cases 80 to 100% of the heavy metals were removed from the clay-mineral-surface.