Pb McQuillan

Putting plant resistance traits on the map: a test of the idea that plants are better defended at lower latitudes

• It has long been believed that plant species from the tropics have higher levels of traits associated with resistance to herbivores than do species from higher latitudes. A meta-analysis recently showed that the published literature does not support this theory. However, the idea has never been tested using data gathered with consistent methods from a wide range of latitudes. • We quantified the relationship between latitude and a broad range of chemical and physical traits across 301 species from 75 sites world-wide. • Six putative resistance traits, including tannins, the concentration of lipids (an indicator of oils, waxes and resins), and leaf toughness were greater in high-latitude species. Six traits, including cyanide production and the presence of spines, were unrelated to latitude. Only ash content (an indicator of inorganic substances such as calcium oxalates and phytoliths) and the properties of species with delayed greening were higher in the tropics. • Our results do not support the hypothesis that tropical plants have higher levels of resistance traits than do plants from higher latitudes. If anything, plants have higher resistance toward the poles. The greater resistance traits of high-latitude species might be explained by the greater cost of losing a given amount of leaf tissue in low-productivity environments.

Displacement of Tasmanian native megachilid bees by the recently introduced bumblebee Bombus terrestris (Linnaeus, 1758) (Hymenoptera : Apidae)

The assertion that the recently introduced large earth bumblebee, Bombus terrestris, does not compete with other bees was investigated by examining the impact of B. terrestris on the foraging of two species of Chalicodoma(Megachilidae) on flowers of Gompholobium huegelii (Fabaceae). Chalicodoma spp. spent less time at each flower during the afternoon in quadrats where B. terrestris foraged than at quadrats from which B. terrestriswas excluded, indicating that standing crops of nectar were depleted by B. terrestris during the course of the day. This decline in resources was associated with reductions in the numbers of flowers visited, and the amount of time spent foraging, by Chalicodoma spp. It is proposed that the native bees avoided foraging in the quadrat where B. terrestris occurred as a response to reduced foraging efficiency in that situation. Thus, B. terrestris displaced these two species of Chalicodoma through competition for a limited resource. The high densities at which B. terrestris occurred, together with its ability to forage at lower ambient temperatures than the native bees, exacerbated the impact of this exotic species. The possibility that this will adversely affect pollination in G. huegelii is also discussed.

The swift parrot, Lathamus discolor (Psittacidae), social bees (Apidae) and native insects as pollinators of Eucalyptus globulus ssp. globulus (Myrtaceae)

It has been argued that the production of sufficient nectar to attract bird pollinators would evolve if the fitness benefits accruing from pollination services by birds, compared with insects, outweighed the cost of increased allocation of photosynthate to nectar. This hypothesis implies that the pollination services provided by birds must be considerably better than those provided by insects with which the plant has evolved. Consistent with this, we found that the endangered native swift parrot Lathamus discolor (Shaw) was a very effective pollinator of the native tree Eucalyptus globulus Labill. in Tasmania, facilitating an average of 76% of the maximum possible seed set for open-pollinated flowers in just one visit to a flower, whereas single flower visits by native insects did not facilitate any seed production. Flowers visited once by either species of introduced social bees, the honeybee Apis mellifera L. or the bumblebee Bombus terrestris (L.), produced less than 7% of the maximum possible seed set for open-pollinated flowers. Hence, easily managed social bees appear to be poor substitutes for bird pollinators in commercial seed orchards of this tree. We propose three possible reasons why this largely bird-pollinated tree has not evolved characters that deter insects from removing nectar.

Pollination services provided by various size classes of flower visitors to Eucalyptus globulus ssp. globulus (Myrtaceae)

Flowers of the commercially important tree Eucalyptus globulus Labill. ssp. globulus were visited by a wide variety of insects and birds within its natural distribution. Flowers were visited so frequently that most available nectar was consumed, but seed production within 5 m of the ground was consistently far less than the maximum possible, indicating the presence of large numbers of inefficient pollinators and few efficient pollinators. Pollen limitation was more severe on fully self-incompatible trees than on partially self-compatible trees, demonstrating that pollinator inefficiency resulted from infrequent outcrossing rather than inability to deposit pollen on stigmas. The flower visitors that were responsible for almost all nectar consumption from flowers within 5 m of the ground were insects that were able to permeate cages with 5-mm apertures but not cages with 1-mm apertures, the most abundant of which was the introduced honeybee Apis mellifera L. These insects contributed less than 20% of the maximum possible seed set, indicating that they were inefficient pollinators. Birds and smaller insects made lesser contributions to seed production, but consumed little nectar within 5 m of the ground. However, anthophilous birds appeared to mostly forage higher in the trees and probably consumed more nectar from, and provided more pollination services to, flowers higher in the trees.

Classic metapopulations are rare among common beetle species from a naturally fragmented landscape

1. The general importance of metacommunity and metapopulation theories is poorly understood because few studies have examined responses of the suite of species that occupy the same fragmented landscape. In this study, we examined the importance of spatial ecological theories using a large-scale, naturally fragmented landscape. 2. We measured the occurrence and abundance of 44 common beetle species in 31 natural rainforest fragments in Tasmania, Australia. We tested for an effect on beetle distribution of geographic variables (patch area, patch isolation and amount of surrounding habitat) and of environmental variables based on plant species, after first accounting for spatial autocorrelation using principal coordinates of neighbour matrices. The environmental variables described a productivity gradient and a post-fire succession from eucalypt-dominated forest to late-successional rainforest. 3. Few species had distributions consistent with a metapopulation. However, the amount of surrounding habitat and patch isolation influenced the occurrence or abundance of 30% of beetle species, implying that dispersal into or out of patches was an important process. 4. Three species showed a distribution that could arise by interactions with dominant competitors or predators with higher occurrence in small patches. 5. Environmental effects were more commonly observed than spatial effects. Twenty-three per cent of species showed evidence of habitat-driven, deterministic metapopulations. Furthermore, almost half of the species were influenced by the plant succession or productivity gradient, including effects at the within-patch, patch and regional scales. The beetle succession involved an increase in the frequency of many species, and the addition of new species, with little evidence of species turnover. Niche-related ecological theory such as the species-sorting metacommunity theory was therefore the most broadly applicable concept. 6. We conclude that classic and source-sink metapopulations are probably rare in this large-scale, naturally fragmented system, although dispersal processes like those occurring in metapopulations may have a substantial influence on community composition. However, deterministic processes (niche specialisation, species-sorting metacommunities and deterministic metapopulations) drive the occurrence or frequency of the majority of species. We urge further research into the prevalence of spatial ecological processes in large-scale natural ecosystems to expand our understanding of the processes that may be important in nature.

Pollinators in seed orchards of Eucalyptus nitens (Myrtaceae)

Flowers of the commercially important tree Eucalyptus nitens (Deane & Maiden) Maiden were visited by a diverse array of insects, but not by birds, in Tasmanian seed orchards. Most species of insects that visited the flowers of E. nitens are likely to be effective pollinators because all common species of visitors carried many grains of Eucalyptus pollen, and the open floral structure facilitates frequent insect contact with stigmas. Seed production also suggested that a wide variety of insects were effective pollinators because flowers were consistently well pollinated, despite differences in flower-visitor communities among orchards and particular branches of flowers. The generalised entomophilous pollination system of E. nitens suggests that effective pollinators should occur in seed orchards of this tree throughout the world, provided that flowering occurs at a time of year conducive to insect activity. Although a wide variety of insects appear to be effective pollinators of E. nitens, introduced honeybees, Apis mellifera L., that are often deployed as pollinators in seed orchards were consistently not attracted to the flowers. The reliance on wild insects as pollinators suggests that seed production in E. nitens may benefit from reduced use of broad-spectrum insecticides in, and near, seed orchards.

A test of the thermal melanism hypothesis in the wingless grass-hopper Phaulacridium vittatum

Abstract Altitudinal clines in melanism are generally assumed to reflect the fitness benefits resulting from thermal differences between colour morphs, yet differences in thermal quality are not always discernible. The intra-specific application of the thermal melanism hypothesis was tested in the wingless grasshopper Phaulacridium vittatum (Sjöstedt) (Orthoptera: Acrididae) first by measuring the thermal properties of the different colour morphs in the laboratory, and second by testing for differences in average reflectance and spectral characteristics of populations along 14 altitudinal gradients. Correlations between reflectance, body size, and climatic variables were also tested to investigate the underlying causes of clines in melanism. Melanism in P. vittatum represents a gradation in colour rather than distinct colour morphs, with reflectance ranging from 2.49 to 5.65%. In unstriped grasshoppers, darker morphs warmed more rapidly than lighter morphs and reached a higher maximum temperature (lower temperature excess). In contrast, significant differences in thermal quality were not found between the colour morphs of striped grasshoppers. In support of the thermal melanism hypothesis, grasshoppers were, on average, darker at higher altitudes, there were differences in the spectral properties of brightness and chroma between high and low altitudes, and temperature variables were significant influences on the average reflectance of female grasshoppers. However, altitudinal gradients do not represent predictable variation in temperature, and the relationship between melanism and altitude was not consistent across all gradients. Grasshoppers generally became darker at altitudes above 800 m a.s.l., but on several gradients reflectance declined with altitude and then increased at the highest altitude.

Nocturnal Mammals, Diurnal Lizards, and the Pollination Ecology of the Cryptic Flowering Acrotriche Serrulata (Ericaceae)

Acrotriche serrulata exhibits a complex and uncommon form of flowering. It starts with a male-phase flower that shows secondary pollen presentation on the perianth and follows with a female phase after the corolla is removed or abscissed. We examined the potential for insects, lizards, and mammals to act as pollinators. Observations and experiments on breeding system, phenology, floral scent, flower visitors, and lizard feeding were undertaken in southern Australia. Acrotriche serrulata sets little fruit by autonomous selfing but readily sets fruit after facilitated geitonogamy and xenogamy. Flower anthesis is diurnal and nocturnal. The nectar profile includes acetaldehyde, ethanol, and ethyl acetate. The nocturnal mammals Trichosurus vulpecula and the introduced Rattus rattus were the only visitors observed to actively forage on the flowers. In contrast, the skinks Egernia whitii, Niveoscincus ocellatus, and Niveoscincus metallicus routinely passed flowers full of nectar and foraged only on those presented during feeding observations. Insects visited the flowers but did not behave as pollinators. Acrotriche serrulata is likely to be pollinated by nocturnal mammals attracted to its flowers by scent. Effective pollinators appear to be rare over some of its range. This may have implications for the long-term reproductive success and conservation of A. serrulata.

Bird Pollination of the Climbing Heath Prionotes Cerinthoides (Ericaceae)

Tubular red and pink flowers often indicate bird pollination. Prionotes cerinthoides, a climbing shrub of the temperate rainforest in Tasmania (Australia) and one of only two members of the most primitive clade of the subfamily Styphelioideae (Ericaceae), has such flowers. We tested the hypothesis that P. cerinthoides is bird pollinated using breeding system experiments, observations of flower visitors, and invertebrate trapping. Flowering phenology, nectar availability, and flower damage were also recorded. Prionotes cerinthoides produced little viable seed in the absence of a pollinator but selfed readily when pollination was facilitated. It appears that P. cerinthoides depends largely on the pollination services of a single native bird species, the eastern spinebill (Acanthorhynchus tenuirostris). The only other flower visitor observed to contact anthers and stigma was the introduced bumblebee (Bombus terrestris). The crescent honeyeater (Phylidonyris pyrrhoptera), the introduced honeybee (Apis mellifera), and the bumblebee were nectar robbers.

Strategic national approach for improving the conservation management of insects and allied invertebrates in Australia: Conservation strategy for Australian insects

Despite progress in recent decades, the conservation management of insects and allied invertebrates in Australia is challenging and remains a formidable task against a background of poor taxonomic and biological knowledge, limited resources (funds and scientific expertise) and a relatively low level of community engagement, education and awareness. In this review, we propose a new, strategic national approach for the conservation of insects and allied invertebrates in Australia to complement and build on existing actions and increase awareness with the general public and government. A review of all species listed under relevant State and Territory Acts, national legislation (EPBC Act) and on international lists (IUCN Red List) indicated that of the 285 species currently listed under these conservation schedules, 10 (3%) are considered extinct, 204 (72%) threatened (Critically Endangered, Endangered or Vulnerable) and 71 (25%) are classified as other (Threatened, Near Threatened, Rare or Least Concern). Comparison of the geographic ranges of listed species in relation to bioregions (IBRA regions) shows a striking discordance in spatial representation across the Australian landscape, reflecting an ad hoc approach to threatened species conservation and the concentration of invertebrate biologists in urban centres of temperate coastal Australia. There is a positive relationship between the number of threatened species and extent of protection according to the National Reserve System within each IBRA region, exemplifying the anomaly in spatial representativeness of listed species. To overcome these shortfalls, we propose a novel educational, regional approach based on selecting, for each of the 89 IBRA regions, a relatively small set of ‘flagship taxa’ (threatened species and/or ‘iconic’ species of high scientific/social value), which are then promoted and/or nominated for listing by the scientific community. Such species could be adopted by local community groups whereby a community‐based regional approach would ensure spatial representativeness of insect conservation across the entire Australian continent. This novel approach may ultimately provide a better strategy for the conservation management of habitats and threatened ecological communities, reducing extinction risk of threatened species and addressing key threatening processes. Members of the Australian entomological community are strongly encouraged to nominate candidate taxa as flagship species for wider promotion and/or listing nationally under the EPBC Act.