Hedgerow presence does not enhance indicators of nest‐site habitat quality or nesting rates of ground‐nesting bees

A major challenge in habitat restoration is targeting the key aspects of a species' niche for enhancement, particularly for species that use a diverse set of habitat features. However, restoration that focuses on limited aspects of a species' niche may neglect other resources that are critical to population persistence. We evaluated the ability of native plant hedgerows, planted to increase pollen and nectar resources for wild bees in agricultural landscapes, to provide suitable nesting habitat and enhance nesting rates of ground‐nesting bees. We found that, when compared to unmanaged field edges (controls), hedgerows did not augment most indicators of nest habitat quality (bare ground, soil surface irregularity, and soil hardness), although coarser soils were associated with higher incidence and richness of nesting bees. Hedgerows did not augment nesting rates when compared to control edges. Although all the bee species we detected nesting were also found foraging on floral resources, the foraging versus nesting assemblages found within a site were highly dissimilar. These results may reflect sampling error; or, species found foraging but not nesting in hedgerows could be utilizing hedgerows as “partial habitats,” nesting outside hedgerow plantings but foraging on the floral resources they provide. We conclude that although hedgerows are known to provide critical floral resources to wild bees especially in resource‐poor intensive agricultural landscapes, simply increasing vegetative diversity and structure may not be simultaneously enhancing nesting habitat for ground‐nesting bees.     

Hedgerows support rich communities of harvestmen (Opiliones) in upland agricultural landscape

Hedgerows play important roles in agricultural landscapes and they increase biodiversity by providing habitat refugia for species sensitive to agricultural disturbance. We have studied the characteristics of the communities of harvestmen (Opiliones) inhabiting hedgerows. Harvestmen are terrestrial arachnids associated with soil surface and subsurface and sensitive to land-use and disturbance. We were specifically interested in quantifying how hedgerow characteristics (e.g., elevation, length, width, connectivity, and plant diversity) affect harvestman diversity and community composition. We expected harvestman diversity and community composition to be positively related to both hedgerow size (area, length, width) and biological attributes of hedgerows (e.g., connectivity, plant community diversity). We surveyed hedgerow characteristics and harvestman communities of 20 hedgerows in an upland agricultural landscape in the Western Carpathians. Hedgerow characteristics were measured in the field or derived from GIS layers and we used correlation and ordination methods to relate them to harvestman community metrics. We found surprisingly high taxonomic richness of harvestmen within the studied hedgerows (15 species). Importantly, the Shannon index of harvestman communities was positively related to hedgerow length and hedgerow tree layer species richness and diversity. Harvestman community composition varied with hedgerow area and width. Despite their small total area, hedgerows represented an important habitat for diverse harvestman communities and hedgerow attributes such as size and tree diversity significantly affected the composition and the Shannon index of harvestman communities. Thus, greater lengths and widths of hedgerows can provide habitats for a higher Shannon index of harvestman communities, within surrounding agricultural landscapes.     

Pollination biology of fruit-bearing hedgerow plants and the role of flower-visiting insects in fruit-set

Background and Aims

In the UK, the flowers of fruit-bearing hedgerow plants provide a succession of pollen and nectar for flower-visiting insects for much of the year. The fruits of hedgerow plants are a source of winter food for frugivorous birds on farmland. It is unclear whether recent declines in pollinator populations are likely to threaten fruit-set and hence food supply for birds. The present study investigates the pollination biology of five common hedgerow plants: blackthorn (Prunus spinosa), hawthorn (Crataegus monogyna), dog rose (Rosa canina), bramble (Rubus fruticosus) and ivy (Hedera helix).

Methods

The requirement for insect pollination was investigated initially by excluding insects from flowers by using mesh bags and comparing immature and mature fruit-set with those of open-pollinated flowers. Those plants that showed a requirement for insect pollination were then tested to compare fruit-set under two additional pollination service scenarios: (1) reduced pollination, with insects excluded from flowers bagged for part of the flowering period, and (2) supplemental pollination, with flowers hand cross-pollinated to test for pollen limitation.

Key Results

The proportions of flowers setting fruit in blackthorn, hawthorn and ivy were significantly reduced when insects were excluded from flowers by using mesh bags, whereas fruit-set in bramble and dog rose were unaffected. Restricting the exposure of flowers to pollinators had no significant effect on fruit-set. However, blackthorn and hawthorn were found to be pollen-limited, suggesting that the pollination service was inadequate in the study area.

Conclusions

Ensuring strong populations of insect pollinators may be essential to guarantee a winter fruit supply for birds in UK hedgerows.Key words: Blackthorn, bramble, Crataegus monogyna, frugivorous birds, hawthorn, Hedera helix, hedgerows, ivy, insect pollination, Prunus spinosa, Rubus fruticosus, Rosa canina     

The value of woody hedgerows for moth diversity on organic and conventional farms

Habitat destruction and degradation are important drivers of biodiversity loss within agro-ecosystems. However, little is known about the effect of farming practices and the value of woody hedgerows on Lepidoptera in North America. The purpose of this work was to study moth diversity in woody hedgerows and croplands of organic and conventional farms. In addition, the influence of vegetation composition and abiotic variables on species richness, abundance, and composition was examined. Moths were sampled with light traps during six weeks in the summer of 2001. Vegetation data and abiotic variables were obtained for all sites. In total, 26,020 individuals from 12 families and 408 species were captured. Most species were uncommon. Only 35 species included >100 individuals while for 71% of species <10 individuals were found. The Noctuidae represented 221 species and 85% of all individuals captured. Woody hedgerows harbored more species and in greater number than croplands. There was no significant difference in moth diversity between organic and conventional farms, except that the Notodontidae were significantly more species rich in organic than in conventional sites. Results show that species richness, abundance, and composition were greatly influenced by habitat types (hedgerow versus crop field) and abiotic variables (minimum temperature which was correlated to moon illumination, rainfall, and cloud cover). Moth species composition was significantly correlated to vegetation composition. This study broadens our understanding of the factors driving moth diversity and expands our knowledge of their geographic range. The maintenance of noncrop habitats such as woody hedgerows within agro-ecosystems seems paramount to preserving the biodiversity and abundance of many organisms, including moths.     

Use of Radio Telemetry for Studying Flight Movements of <Emphasis Type="Italic">Paysandisia archon</Emphasis> (Lepidoptera: Castniidae)

The moth Paysandisia archon is an invasive species that infests palm trees in the Mediterranean Basin. The immature stages occur exclusively inside the palm crown, whereas adults fly to mate and locate a new host plant. Here, we describe the use of small radio transmitters (0.27 g) for tracing the movements of P. archon adults. We report the first successful use of radio telemetry to track flight distances and space use of a flying moth. Our study was carried out using 11 tagged moths released on the Maguelone Peninsula in southern France. Although the males were successfully tracked within a restricted area, estimated at 4 ha, most of the tagged females immediately flew distances over 500 m, disappearing beyond the maximum detection range of the 30 ha study area. Flights for mating, resting and, likely, oviposition covered distances of 11.6 m to 224 m in males and 16.8 m to >500 m in females. We found evidence that both sexes are active during the warmer temperatures of the day. In contrast, the moths were inactive when the relative humidity was high. Moreover, the P. archon moths do not seem to reside on the host palm trees. Our data show a high mobility of females, which may be responsible for the spread of the first recorded Castniidae in France by laying eggs far from the palm trees where they emerged.     

Habitat preference and mobility of <Emphasis Type="Italic">Polia bombycina</Emphasis>: are non-tailored agri-environment schemes any good for a rare and localised species?

General agri-environment schemes (AES) have been shown to benefit widespread species, but there is little information on the extent to which rare, more localised, species may also benefit. We tested whether AES options aimed at increasing general biodiversity also benefit a highly endangered moth, Polia bombycina, without species-specific tailoring. We assessed effects on its abundance of two AES options, wide field margins and hedgerow trees, using light traps at the landscape-scale and for mark-release-recapture at the farm-scale. We hypothesized that abundance would be highest at wide field margins and at hedgerow trees, and that if hedgerow trees conferred a positive effect, individuals would be more likely to follow hedgerows than crossing exposed fields while on the move. The results showed that significantly more individuals were captured at sites with a hedgerow tree. Numbers were also higher at wide margins, but this was not statistically significant, and no individuals were caught at field centres. Our study suggests that general options within appropriately designed and implemented AES aimed at increasing overall biodiversity in intensive agricultural landscapes have the potential to not only benefit common, widespread habitat generalists, but some rare and more endangered species as well. P. bombycina serves as an example of how general AES options, existing and novel ones alike, might cater for the needs of rare and localised species. As the precise ecological requirements of most invertebrate species remain unknown, we urge scientists and governments to address the challenge to research and design truly general AES, which options should be able to deliver not only for widespread species but also for the less-widespread counterpart of farmland biodiversity.     

Factors influencing the spatial distribution of forest plant species in hedgerows of North-western Germany

In North-western Germany woodland fragmentation has caused a decline in many forest plant species. Hedgerows partly offer a similar environment as forests and have been identified as potential habitats for forest plants in various studies from North America and Western Europe. The objective of this study was to examine whether this applies also to Central Europe and which variables affect the spatial distribution and abundance of forest plant species in hedgerows on a local scale. Three hedgerow networks north of the city of Bremen, Germany, were selected as study areas and divided into totally 515 hedgerow segments. In each segment we recorded all vascular plants and a large number of explanatory variables relating to structure, spatial configuration, environment and management. Averaged across species there was a predominant effect of environmental factors on the occurrence of forest species in the hedgerows, followed by spatial configuration and management. Hedgerow structure was found to be less important. In general, forest species were favored by low nutrient and light availability as well as high connectivity with other hedgerows or forest; they avoided hedgerows with a west-easterly orientation and an adjacent land use in the form of fields or grasslands. Forest species found and not found in hedgerows did not differ in their environmental preferences or life history traits. The number of threatened forest species in the hedgerows, however, was lower than expected with respect to their overall proportion to the total number of forest species in the region.     

Coping with third parties in a nursery pollination mutualism: Hadena bicruris avoids oviposition on pathogen-infected, less rewarding Silene latifolia

In nursery pollination systems, pollinator offspring usually feed on pollinated fruits or seeds. Costs and benefits of the interaction for plant and pollinator, and hence its local outcome (antagonism-mutualism), can be affected by the presence of 'third-party' species. Infection of Silene latifolia plants by the fungus Microbotryum violaceum halts the development of fruits that provide shelter and food for larvae of the pollinating moth Hadena bicruris. We investigated whether the moth secures its benefit by selective oviposition on uninfected flowers. Oviposition was recorded in eight natural populations as a function of plant infection status, local neighbourhood, plant and flower characteristics. Oviposition was six times lower on flowers from infected than on those from uninfected plants. Oviposition decreased with decreasing flower and ovary size. Moths could use the latter to discriminate against diseased flowers. Although moths show an adaptive oviposition response, they reduce the future potential of healthy hosts because they still visit infected plants for nectar, vectoring the disease, and they reduce any fitness advantage gained by disease-resistant plants through selective predation of those plants.     

Temporal changes in floral resource availability and flower visitation in a butterfly

Foraging affects survival and reproductive success in animals, including flower-visiting insects. Plant-derived floral food resources (i.e. nectar and pollen) may be rapidly changing in space and time and pollinators may need to quickly switch to new resources. Butterflies are suitable model organisms to investigate foraging behaviour of insect pollinators, because they can be easily monitored under natural conditions. We studied flower visitation patterns in the Clouded Apollo butterfly Parnassius mnemosyne in relation to the abundance of available floral resources. We recorded flower visitation daily in individually marked butterflies, listed flowering species and estimated flower abundance categories every 3 days in a single meadow, during five consecutive flight periods. Butterflies visited 35 nectar plants from the 71 species available. Few nectar plants were frequently visited (visit ratios for the annually most visited species: 37–60%), many were scarcely visited and no visits were observed on several abundant species. Flower abundance and visit ratio varied among years and within flight periods. The number of visits increased with flower abundance in the seven most frequently visited plant species, but not in the occasionally visited ones. Beside their choosiness, Parnassius mnemosyne butterflies were able to adjust foraging behaviour to rapidly changing resource distributions. Diet selectivity in adults might increase the vulnerability of this species. However, visitation plasticity may mitigate the effect of the lack of some nectar plants, as complementary resources can be used as alternatives.     

Hedgerows as corridors for woodland plants: a test on the Po Plain,northern Italy

The use of hedgerows as corridors for forest vascular species has been widely studied, but only in humid oceanic and continental climates; no replicated trials have ever been performed on corridor function. Given these premises, a study was done on the eastern Po Plain, in a transition area between the Temperate (Eurosiberian) and Mediterranean climatic zones, adopting the same sample shape and dimensions as a North-American study [Corbit et al. (1999) J Ecol 87:220–232]. The following research questions were posed: (1) how common are forest species in hedgerows? (2) do origin, isolation, distance from source, width and adjacent land-use factors correlate with the frequency of forest species? (3) are hedgerows corridors for forest species? To address these, three functional types of hedgerows, identified by comparing old aerial-photos, were sampled: remnant attached (n = 12) and remnant isolated (n = 6) with respect to the nearest woodland and regenerated attached (n = 4). If wooded patches were a source for hedgerows, then regenerated hedgerows should be more similar to an adjacent woodland than an isolated remnant. A 900 m² circular plot in woodlands and an adjacent 90-m transect along hedgerows were sampled for the presence and cover of all plant species, then 39 woodland taxa were selected. Significant differences between the three hedgerow types emerged in forest species richness, but not in cover. The forest species composition in both remnant and regenerated attached hedgerows showed a strong affinity with the adjacent stand, implying a dispersal process from woodland (source) to regenerated hedgerows (sink). A distance effect on forest species distribution clearly linked to a corridor function was found only in regenerated hedgerows, while in the remnant attached ones, even with a composition similar to that of the nearest woodland source, other additional factors cannot be ignored to explain the fine scale distribution of forest species. The cover of the most common ant-dispersed species showed a similar distance effect while vertebrate-dispersed ones did not show any significant trend with distance from woodlands. Habitat suitability for forest species was affected by width, especially in hedges wider than 12 m, but not by adjacent land use.     

Patterns of an elevational gradient affecting moths across the South Korean mountains: effects of geometric constraints,plants, and climate

We investigated elevational richness patterns of three moth groups (Erebidae, Geometridae, and Noctuidae) along four elevational gradients located on one northern and three southern mountains in South Korea, as well as the effects of plants and climatic factors on the diversity patterns of moths. Moths were collected with an ultraviolet light trap at 32 sites from May through October, 2013. Plant species richness and mean temperatures for January and June were acquired. Observed and estimated moth species richness was calculated and the diversity patterns with null models were compared. Species richness along four elevational gradients peaked at mid-elevations, whereas deviations occurred at elevations below mid-peak in the southern mountains and elevations higher than mid-peak on the northern mountain. Species richness curves of three moth groups also peaked at mid-elevations throughout South Korea. However, the species richness curves for Erebidae were positively skewed, indicating that a preference for lowlands, whereas curves of the Geometridae were negatively skewed, indicating a preference for highlands. The mid-peak diversity pattern between plants and moths on the Korean mountains showed an elevational breadth that overlapped between 800 and 900 m. Multiple regression analysis revealed that plant species richness and January mean temperature significantly influenced moth species richness and abundance. The rapid increase in mean annual temperature in the Korean peninsula and the unimodal elevational gradients of moths across the country suggest that an uphill shift in peak optimum elevation and changes in the highest peak of the curve will occur in the future.     

Effects of hedgerows on bats and bush crickets at different spatial scales

Biodiversity is threatened by the loss and fragmentation of habitats. The role of hedgerows in maintaining biodiversity is well established, but few studies have addressed the importance for biodiversity of the intrinsic characteristics of hedgerows and the quality of hedgerow networks along a spatial scale. We examined three quality indices providing information at different territorial levels: density in the landscape, structural diversity and wood production. We performed an acoustic survey in a grassland to estimate the species abundance and community composition of bats (9 taxa) and bush crickets (11 species). Using an approach based on species and traits, we assessed how hedgerow quality influenced the activity of these taxa at different spatial scales (from 50 to 1000 m) and focused on three types of traits: bush cricket mobility ability, bat foraging strategy and habitat specialization. In general, our results showed the importance of hedgerow quality for bats and bush crickets, but the strength of the association between taxa and hedgerows varied substantially among the species and the spatial scales. Although it depends on the taxa, the production, density and structural diversity of hedgerows each had an overall positive effect. Our results suggested that these effects were generally more important at large scales. The scale effect of the production index is the best predictor of activity for bat and bush cricket taxa and traits. Our results showed the importance of hedgerow quality for the ecology of bat and bush cricket communities and could be used to improve conservation management.     

Large moths captures by a pest monitoring system depend on farmland heterogeneity

As intensive farmlands cover increasing areas of the world, associated biotic richness is crucial for the biodiversity of entire regions. Using data on non‐target Macrolepidopteran moths captured by a crop pest monitoring system, we compared local (100 m perimeter)‐ and landscape‐scale (1000 m perimeter) predictors of the numbers of moth individuals and moth species richness. During a single year (2009), eighteen light traps captured 91 726 individuals of 564 moths species. Typically for biotically impoverished habitats, the catches were dominated by a few superabundant species. Even in these impoverished assemblages, numbers of species increased with increasing herb and woody plants diversity (100 m around the traps), crop diversity (1000 m perimeter), landscape composition (1000 m) and configuration (100 and 1000 m). Abundance of the catches increased only with woody plants diversity in 100 m perimeters. In separate analyses of two species‐rich families, the presumably less mobile Geometridae increased with landscape configuration (i.e. density of edges) within 100 m perimeters around the traps, whereas the species richness of more mobile Noctuidae also reflected the landscape composition (i.e. proportional representation of land covers) at 100 m perimeters. Proportional representation of pest species decreased with increasing richness of herb and woody plants. Taken together, farmland heterogeneity increases moth species richness, whereas abundance of the catches mainly depends on local factors in the vicinity of light traps, and the local factors are more important for presumably less mobile Geometridae than for more mobile Noctuidae.     

Bee Preference for Native versus Exotic Plants in Restored Agricultural Hedgerows

Habitat restoration to promote wild pollinator populations is becoming increasingly common in agricultural lands. Yet, little is known about how wild bees, globally the most important wild pollinators, use resources in restored habitats. We compared bee use of native and exotic plants in two types of restored native plant hedgerows: mature hedgerows (>10 years from establishment) designed for natural enemy enhancement and new hedgerows (≤2 years from establishment) designed to enhance bee populations. Bees were collected from flowers using timed aerial netting and flowering plant cover was estimated by species using cover classes. At mature hedgerow sites, wild bee abundance, richness, and diversity were greater on native plants than exotic plants. At new sites, where native plants were small and had limited floral display, abundance of bees was greater on native plants than exotic plants; but, controlling for floral cover, there was no difference in bee diversity and richness between the two plant types. At both mature and new hedgerows, wild bees preferred to forage from native plants than exotic plants. Honey bees, which were from managed colonies, also preferred native plants at mature hedgerow sites but exhibited no preference at new sites. Our study shows that wild bees, and managed bees in some cases, prefer to forage on native plants in hedgerows over co‐occurring weedy, exotic plants. Semi‐quantitative ranking identified which native plants were most preferred. Hedgerow restoration with native plants may help enhance wild bee abundance and diversity, and maintain honey bee health, in agricultural areas.     

Ecology of Lepidoptera associated with bird nests in mid‐Wales,UK

1. Bird nests are ubiquitous but patchy resources in many terrestrial habitats. Nests can support diverse communities of commensal invertebrates, especially moths (Lepidoptera). However, there is a shortage of information on the moths associated with bird nests, and the factors influencing their abundance, diversity and composition. 2. Two hundred and twenty‐four nests, from 16 bird species, were sampled from sites in mid‐Wales (UK) and the moths that emerged from them were recorded. 3. Seventy eight percent of nests produced moths, with 4657 individuals of ten species recorded. Moth communities were dominated by generalist species rather than bird nest specialists. 4. Open nests built in undergrowth supported significantly fewer moths than nests in enclosed spaces (for example, nesting boxes). The occurrence of fleas was positively associated with the incidence and abundance of moths. There was no evidence that different nest types supported different moth communities.     

蝴蝶在生境和生物小区之间的移位伴随着对外来蜜源的利用

在发育成熟的温带环境中,植食性昆虫群落能迅速适应引入植物并将其作为幼虫的食物和花蜜.我们研究了经过森林砍伐的热带环境中蝴蝶对利用引入植物作为蜜源植物的适应快慢程度,并研究了蝴蝶-显花植物在新的生物小区中出现的范围,发现蝴蝶对引入显花植物的利用和探访多于本地植物,这与引入植物在调查地点、生物小区和植物丰度中的普遍性有关.此外,取食花蜜的蝴蝶和显花植物与正在形成的的生物小区有关,例如路边、农田、集约耕地以及花园.在这些新生物小区中,引入植物很重要,因为它们为蝴蝶提供了蜜源.     

Development of a synthetic plant volatile-based attracticide for female noctuid moths. I. Potential sources of volatiles attractive to Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

This paper is the first of a series which will describe the development of a synthetic plant volatile-based attracticide for noctuid moths. It discusses potential sources of volatiles attractive to the cotton bollworm, Helicoverpa armigera (Hübner), and an approach to the combination of these volatiles in synthetic blends. We screened a number of known host and non-host (for larval development) plants for attractiveness to unmated male and female moths of this species, using a two-choice olfactometer system. Out of 38 plants tested, 33 were significantly attractive to both sexes. There was a strong correlation between attractiveness of plants to males and females. The Australian natives, Angophora floribunda and several Eucalyptu s species were the most attractive plants. These plants have not been recorded either as larval or oviposition hosts of Helicoverpa spp., suggesting that attraction in the olfactometer might have been as nectar foraging rather than as oviposition sources. To identify potential compounds that might be useful in developing moth attractants, especially for females, collections of volatiles were made from plants that were attractive to moths in the olfactometer. Green leaf volatiles, floral volatiles, aromatic compounds, monoterpenes and sesquiterpenes were found. We propose an approach to developing synthetic attractants, here termed 'super-blending', in which compounds from all these classes, which are in common between attractive plants, might be combined in blends which do not mimic any particular attractive plant.     

Moths count: recording moths for conservation in the UK

Insects are under-represented in current assessments of biodiversity loss at global and national scales. Butterflies, and a few other insect taxa, have been used as indicators of biodiversity change and as flagships for conservation, especially in temperate zones, but these groups are typically species-poor and may not be representative of insects as a whole. Macro-moths, on the other hand, are an important component of UK biodiversity, in terms of both species richness and ecosystem function. Moth abundance has decreased significantly in the UK and there is rapidly growing interest in the surveillance and monitoring of macro-moths among amateur and professional scientists. The Moths Count project was instigated to raise awareness of moths, increase moth recording and set up a long-term National Moth Recording Scheme for c.900 species of macro-moth in the UK. Since 2006, Moths Count has promoted moths to millions of people, trained and engaged thousands in recording and collated over eight million species distribution records into the National Moth Recording Scheme. These data, though incomplete at present, are already contributing to assessments of biodiversity loss and to conservation initiatives. We present initial results which show that substantial changes are already evident for macro-moths in the UK. The northern range margins of a sample of 12 species have shifted northwards by 194.8 km on average between 1982 and 2009 (7.8 km year^?1 over the 25 years between survey mid-points). Provisional distribution trends (not corrected for variation in recording effort) were calculated for 43 species and the results corroborated both positive and negative population-level changes assessed previously.     

Is microclimate important for Orthoptera in open landscapes?

Orthoptera were monitored on field edge public footpaths on the east (leeward) and west (windward) side of hedgerows in Chelmsford, UK, in 2006. A total of 6 species were recorded from footpaths on the leeward side of hedgerows probably due to the shelter from the prevailing westerly winds provided by the trees and shrubs. On the windward side of hedgerows species richness and abundance of Orthoptera were reduced (only 4 species were recorded). It is suggested that shelter from the wind and the exposure to early morning sunlight for Orthoptera on the east side of hedgerows are important factors governing their occurrence on farmland. Many replicates had Environmental Stewardship (ES) scheme field margins adjacent but they did not affect Orthoptera species richness or abundance.     

Determinants of diversity in afrotropical herbivorous insects (Lepidoptera: Geometridae): plant diversity,vegetation structure or abiotic factors?

Aim This study was conducted to investigate the potential of predicting alpha diversity and turnover rates of a highly diverse herbivorous insect family (Geometridae) based on vascular plant species richness and vegetation structure. Location The study was carried out on the south‐western slopes of Mount Kilimanjaro within a wide range of habitats between 1200 and 3150 m elevation. Methods The floristic and structural composition of the vegetation was recorded at 48 plots of 400 m². Geometrid moths were sampled manually at light sources located at the plot centres. Principal components analysis, redundancy analysis and multiple linear regression were used to explore how alpha diversity and species turnover of geometrid moths are related to vegetation structure and plant species richness. Results Alpha diversity of geometrid moths was significantly correlated with species diversity patterns in the most common vascular plant families (R² = 0.49) and with plant structural parameters (R² = 0.22), but not with overall floristic diversity. Species turnover of geometrid moths was strongly linked to diversity changes in a range of plant families (40% explained variance), less strongly to changes in vegetation physiognomy (25%), and only weakly to overall floristic diversity (5%). Changes in elevation were a better predictor of both alpha diversity and species turnover of geometrid moths than any principal component extracted from the vegetation data. Main conclusions Vegetation composition, diversity and structure all showed significant correlations with the diversity and species composition of geometrid moth assemblages. Nevertheless, in most cases relationships were indirect, via environmental parameters such as temperature and humidity, which influenced both vegetation and moth fauna. Possible direct links between geometrid diversity and potential food plants were much weaker. The lack of a significant correlation between overall plant species richness and geometrid diversity indicates that tropical geometrid moths may not be very selective in their food plant choice. Accordingly, a clear correlation between floral diversity and herbivore species richness must be regarded as overly simplistic, and the diversity of vascular plants cannot universally be used as a suitable biodiversity indicator for diverse insect taxa at higher trophic levels.