Larval nutritional environment determines adult size in Japanese horned beetles <Emphasis Type="Italic">Allomyrina dichotoma</Emphasis>

The effects of larval nutrition and parental size on offspring horn (male) and body size (male and female) were examined in the Japanese horned beetle Allomyrina dichotoma L. (Coleoptera: Scarabaeidae). Offspring-parent regressions for both horn size and body size of males show no heritable effect, and the magnitudes of these traits were primarily determined by the larval nutritional condition. Male Allomyrina dichotoma also displayed dimorphic horn size-body size allometry, that is, larger males had longer horns relative to their body size and vice versa. Because it has been suggested that males of different body sizes adopt different reproductive tactics, the dimorphic horn size–body size allometry and male reproductive tactics are also a result of the larval environment. Similarly, female body size was determined by larval nutrition, and, thus, larval condition might influence future female fecundity. Females under low nutrition treatment spent longer duration of the third larval instar than females under high nutrition. Females under poor nutrition treatment probably attempted to be as large as possible by the extent of larval duration. Since horn and/or body sizes of males and females affect their fitness, this suggests the evolution of female choice for better oviposition site.     

Faecal pellets of Reeves’ muntjac,<Emphasis Type="Italic"> Muntiacus reevesi</Emphasis>: defecation rate,decomposition period,size and weight

Captive muntjac fed on vegetation had a daily defecation rate of 7 to 8.2.pellet groups. Even in the cold month of February 97.6% of pellets decayed within 80 days but for 8 other months the range was 4 to 23 days. Emphasis is given to the need for site-specific information when decay rate is required to assess population size from dung counts. The morphology, dimensions, weight and group size of pellets are described as an aid to distinguish them from the faeces of other cervids.     

The use of ground beetles (Coleoptera: Carabidae) in conservation assessments of exposed riverine sediment habitats in Scotland and northern England

Exposed riverine sediments (ERS) are an important invertebrate habitat. Ground beetle data from pitfall trap surveys of 165 sites in the catchments of the Rivers Carron, Nith, Spey, Tweed and Eden and from 48 sites in the catchments of the Rivers Blyth, Breamish, Coquet, Glen, Pont, South Tyne, Till, Tweed and Tyne were used to produce ERS habitat classifications in Scotland and northern England respectively. Within each habitat type the quality of sites were assessed using indices based on rarity and fidelity values and using species richness as a measure of diversity. Considerable variation in these indices was seen within and between habitat types, showing potential for their use in assessing site quality and for ranking sites within habitats. The use of standardised invertebrate survey and distribution data, together with species assemblage information, for the conservation of invertebrate habitat types as an alternative to the use of selected indicator species, is discussed.     

Assessing tillage disturbance on assemblages of ground beetles (Coleoptera: Carabidae) by using a range of ecological indices

Many ecological studies have used diversity indices to assess the impact of environmental disturbance. In particular, ground beetles have been advocated as a good group for assessing disturbance. Most studies on various organisms have used only one or two indices. For our study of the impact of tillage disturbance on carabid beetles in farm fields in southern Ontario, Canada, we used seven different diversity indices (richness, Shannon–Wiener, Berger–Parker, Q-statistic, Margalef, and evenness). Few studies have used deviation from diversity abundance models as a measure of disturbance; however, we use three that are applicable to our data (geometric, log-normal and log-series). The indices and models were used to test the null hypothesis that there is no change in diversity with increasing tillage disturbance, and that there is no difference in diversity with different crops or years. We were not able to reject the null hypothesis that there is any diversity difference among farms. We also found that there was no single diversity index or model that was better than any other at detecting disturbance. These results are supplemented by a meta-analysis of 45 published data sets for the same taxon but in different habitats. The meta-analysis supports the conclusions from our field research that diversity indices and models are not useful for detecting the possible effect of disturbance on assemblages of carabid beetles.     

Leaf litter inhabiting beetles as surrogates for establishing priorities for conservation of selected tropical montane cloud forests in Honduras, Central America (Coleoptera; Staphylinidae, Curculionidae)

Thirteen tropical montane cloud forests (TMCFs) in Honduras and adjacent El Salvador were evaluated for species diversity and endemism in leaf litter inhabiting Curculionidae (weevils) and Staphylinidae in June and August of 1994. Totals of 26,891 specimens representing 293 species of Curculionidae, and 7349 specimens representing 224 species of Staphylinidae, were collected. Regional endemism was high with 173 species (58.7% of total) of Curculionidae and 126 species (56.3% of total) of Staphylinidae, restricted to single sites. Measures of diversity (number of observed species [Sobs]; number of endemic species) and estimates of biodiversity (Chao 2, first and second order Jackknife and Bootstrap richness estimators) are given for each site for Curculionidae and Staphylinidae. Priority-areas analyses based on Sobs (Greedy), Sobs, Chao 2, number of endemic species, site complementarity and higher taxonomic diversity (Curculionidae only) are presented. Weak or lack of correlation was noted between site area and site diversity for either Curculionidae or Staphylinidae. The optimum sequence for site conservation was determined based on Sobs (Greedy). Four sites are identified as the highest conservation priorities; Parque Nacional Montecristo, P.N. La Muralla, P.N. Santa Barbara and P.N. Comayagua. Identification as high priority sites supports their designation as Parques Nacionales rather than the less diverse Reservas Biologias or Reservas Vidas Silvestres. While closely approximating performance of Sobs (Greedy), no one of Sobs, number of endemics, Chao 2 or site complementarity give results equivalent to the optimum sequence based on Sobs (Greedy) and the latter is concluded to be the best method for establishing conservation priorities in TMCF. Results of the analyses based on one of Curculionidae or Staphylinidae differ in the ordering of site priorities based on each of Sobs, Chao 2 or number of endemics at each site, with at best, weak positive correlations between results based on each taxon. Data from other taxa are necessary to determine if one of Curculionidae or Staphylinidae emerges as the better surrogate for general patterns of biodiversity in TMCF. Conservation strategies in Central America should emphasize the importance of TMCF particularly in view of high regional endemism. In formulating these strategies, consideration needs to be given to the preservation of many small regional preserves rather than fewer larger preserves. Data from inventories of other taxa should be included where available and all biological data should be integrated with social and cultural issues of regional importance.     

Review Reflections on the biology, morphology and ecology of the Macrochelidae

The Macrochelidae is a cosmopolitan family of predatory mesostigmatic mites, many of which occupy specialized and often unstable habitats. Most known species have adapted to life in dung deposits where prey is plentiful and the potential exists for rapid population growth. Phoresy on co-occurring flying insects plays a vital role in assuring niche continuity for macrochelids in these ephemeral substrates. A brief general review of some of the earlier highlights of macrochelid research is presented, followed by a discussion of the emergence of phoresy as a major survival strategy in the Macrochelidae associated with dung beetles. Special emphasis is placed on the behavioural and chemical mechanisms that mediate phoretic specificity of macrochelid species in the unique n-dimensional universes of their scarab hosts. Phylogenetic analysis of selected phoretic and non-phoretic macrochelid taxa has shown a strong correlation between phoretic state and evolutionary position, indicatin g that an increasing commitment to phoresy in the Macrochelidae is correlated with an advance from early derivative to terminal taxa. Laboratory and field observations have confirmed the importance of chemical, behavioural and ecological factors in maintaining the integrity of the relationship between phoretically specific macrochelids and their dung beetle hosts. © Rapid Science Ltd. 1998     

Diet affects female mating behaviour in a seed‐feeding beetle

In species where males provide nuptial gifts, females can improve their nutritional status and thus increase their fecundity by mating when in need of resources. However, mating can be costly, so females should only mate to acquire resources when the need for resources is large, such as when females are nutritionally‐deprived. Two populations of the seed‐feeding beetle Callosobruchus maculatus, a species that produces relatively large nuptial gifts, are used to test whether female nutritional status affects mating behaviour. Female access to water, sugar and yeast are manipulated and the fitness consequences of these manipulations are examined together with the effects of diet on the propensity of nonvirgin females to mate. Access to water has a small but significant effect on mass loss over time, lifespan and fecundity of females, relative to unfed controls. Access to sugar (dissolved in water) improves female fecundity and lifespan above that of hydrated females but access to yeast has no positive effects on female survival or reproduction. Diet has a large effect on both receptivity of nonvirgin females to a male and how quickly they accept that male. Unfed females are both more likely to mate, and accept a mate more quickly, than females provided access to water, which are more likely to mate and accept a mate more quickly than females provided with sugar. This rank order of behaviours matches the order predicted if females increase their mating rate when nutritionally deprived (i.e. it matches the effect of diet on female fitness). The results obtained also suggest that mate choice may be condition‐dependent: females from one population (Burkina Faso) show a preference for large males when well‐fed but not when unfed, although this result is not found in a second population (South India). It is concluded that nutritionally‐deprived females are more receptive to mates than are well‐fed females, consistent with the hypothesis that females ‘forage’ for nuptial gifts, or at least more willingly accept sperm in exchange for nuptial gifts, when they are nutritionally deprived.     

Assessing the origin of Neotropical mountain dung beetle assemblages (Scarabaeidae: Scarabaeinae): the comparative influence of vertical and horizontal colonization

Aims The fauna of mountains and their surrounding regions are likely to be influenced principally by two biological processes: horizontal colonization along similar altitudinal levels by elements originating from lineages inhabiting higher latitudes; and vertical colonization by lineages from the same latitude, but at lower altitudes. We examine whether the expected patterns derived from the latter process can be observed in mountain dung beetle assemblages. Specifically, we study the variation in species composition and richness with altitude in five regions spanning elevation gradients, analysing whether the altitudinal rates of change in the number of species and genera differ, and whether beta‐diversity scores for adjacent sites in each altitudinal gradient are different for species and genera. Location Eastern Cordillera of the Colombian Andes. Methods Field work was carried out in 1997–99 at 27 sites in five regions with elevation gradients, with 10–32 pitfall traps placed in each site. For each altitudinal level the numbers of species and genera were analysed with respect to altitude, and the slope of the linear regression between these variables was calculated. The slope of the curve of the altitude against the cumulative number of species and genera was also calculated for each altitudinal gradient to describe the compositional change between adjacent sites (beta diversity). Species and generic slopes were compared using analysis of covariance. The turnover of species along each altitudinal gradient was measured using presence/absence data and Cody's beta‐diversity index between adjacent pairs of sites. A cluster analysis was used to detect faunistically homogeneous groups of localities. Results Species richness always decreased with altitude, although the slopes did not differ significantly from zero. The number of genera also decreased with increasing altitude, but generally at a significantly slower rate than for species. Variation in the species beta‐diversity scores between altitudinal levels did not follow a homogeneous pattern in the different regions. Two main altitudinal groups of sites with a boundary c. 1500–1750 m a.s.l. can be detected with respect to faunistic similarity. Low‐ and mid‐altitude sites are inhabited by all of the genera (19) and 80% of all species collected. Eight genera and 61 species (c. 60% of the total) are unable to inhabit high‐altitude sites, and only 20 species appear to be exclusive to these high‐altitude environments (> 2000 m a.s.l.). Main conclusions The dominant processes explaining dung beetle composition in the high north‐eastern Andean mountains are probably those of vertical colonization. The limited role of horizontal colonization processes, or colonization from northern or southern lineages, could be a consequence of the isolation and recent geological origin of these mountains.