Habitat use and diet of two stream gobies of the genus Rhinogobius in south-western Shikoku,Japan

The importance of interspecific competition to habitat use by two congeneric stream gobies, Rhinogobius sp. LD (large-dark type) and CB (cross-band type), was studied by: (i) examining differences in habitat use by each species along the course of the stream; and (ii) comparing microhabitat use and the diet of each species between in allopatry and in sympatry in tributaries of the Shimanto River, south-western Shikoku, Japan. Rhinogobius sp. LD mainly used riffles through the course of the stream. Although CB also mainly used riffles in the lower reaches where CB was numerically dominant, the greater use of riffles by CB was not observed in upper reaches where LD was dominant. Microhabitat analysis revealed that both LD and CB preferred lower bottom velocity in faster current in both allopatry and sympatry. In sympatry, however, LD used coarser substrate and faster current than CB, and both LD and CB used narrower ranges of microhabitat conditions than in allopatry. Dietary analysis indicated that both allopatric and sympatric LD preferred baetids, which are apt to drift, suggesting they adopted ambush foraging. Allopatric CB preferred leptophlebiids and chironomids, which are also apt to drift, whereas sympatric CB did not prefer such invertebrates. Overall results of this study suggest that LD and CB compete for better feeding habitats, CB shift their habitat use and foraging mode under the influence of LD, and current velocity and substrate coarseness are key factors in their habitat segregation.

     

Abundance and Borrelia burgdorferi-infection Prevalence of Nymphal Ixodes scapularis Ticks along Forest–Field Edges

More than 19,000 human cases of Lyme disease (LD) are reported each year in the United States. Lyme disease cases occur when humans are exposed to the bacterium Borrelia burgdorferi through the bite of an infected ixodid tick. The probability of human exposure to infected ticks results from a combination of human behaviors and entomological risk. Human behaviors include use of tick habitats, use of protective clothing, and grooming for tick removal. Entomological risks include the density of ticks in a habitat and the proportion of these that are infected with B. burgdorferi. Recent studies have suggested that humans are at higher risk of exposure to B. burgdorferi near edges between forests and herbaceous communities, including lawns and old fields, but whether this increased risk is a function of human behaviors, entomological risk, or both, is unknown. We assessed entomological risk across forest–old field edges in Dutchess County, NY. Densities of ticks and of infected ticks were considerably higher within forests than at forest–field edges, and were lowest within fields. Thus, edges between forests and fields do not pose a higher entomological risk than do the forests themselves, although risk at the edge is higher than in herbaceous habitat. Landscapes with abundant edges between forested and herbaceous habitat, and roughly even proportions of both, might attract both heavy human use and pose moderately high entomological risk, and thus could be targeted for mitigation. We suggest that determining appropriate methods for reducing human exposure to LD requires differentiating entomological risk from human behaviors.     

Habitat attribute similarities reduce impacts of land‐use conversion on seed removal

Changes in land use strongly influence habitat attributes (e.g., herbaceous ground cover and tree richness) and can consequently affect ecological functions. Most studies have focused on the response of these ecological functions to land‐use changes within only a single vegetation type. These studies have often focused solely on agricultural conversion of forests, making it nearly impossible to draw general conclusions across other vegetation types or with other land‐use changes (e.g., afforestation). We examined the consequences of agricultural conversion for seed removal by ants in native grassland, savanna, and savanna‐forest habitats that had been transformed to planted pastures (Brachiaria decumbens) and tree plantations (Eucalyptus spp.) and explored if changes in seed removal were correlated with differences in habitat attributes between habitat types. We found that land‐use changes affected seed removal across the tree cover gradient and that the magnitude of impact was influenced by similarity in habitat attributes between native and converted habitats, being greater where there was afforestation (Eucalyptus spp in grassland and savanna). Herbaceous ground cover, soil hardness, and tree richness were the most important habitat attributes that correlated with differences in seed removal. Our results reveal that the magnitude of impact of land‐use changes on seed removal varies depending on native vegetation type and is associated with the type of habitat attribute change. Our findings have implications for biodiversity in tropical grassy systems: afforestation can have a greater detrimental impact on ecological function than tree loss.     

Role of interspecific competition in the coexistence ofApodemus argenteus andA. speciosus (Rodentia: Muridae)

Reciprocal-removal experiments with two replicates were conducted to test for the role of interspecific competition in the coexistence ofApodemus argenteus andA. speciosus. Population density, rate of appearance of new (unmarked) individuals, reproduction, survival rate and habitat use were monitored during pre- and removal periods. In both removal experiments, the removal ofA. argenteus had little effect onA. speciosus, while that ofA. speciosus affected several population characteristics ofA. argenteus. Namely, the removal ofA. speciosus shifted the distribution ofA. argenteus to the habitat with a denser shrub cover in one experiment. Also, the removal increased the population densities and appearance rates of new individuals ofA. argenteus in another experiment. Interspecific interactions between the two species appeared to be a one-way action fromA. speciosus toA. argenteus. In removal periods in both experiments, the rates of appearance of new individuals in each species were the highest on the grid where that species was removed. These results suggest that, though interspecific competition occurred between the two species, intraspecific competition had greater effects than interspecific competition on the abundance and habitat use ofA. argenteus andA. speciosus. This implies that the fundamental niches ofA. argenteus andA. speciosus differ potentially, which may play an important role in the coexistence of the two species.     

Patterns of food and microhabitat resource use by two benthic gobiid fishes

The mechanisms responsible for different patterns of habitat use by two benthic gobiid fishes, Acentrogobius sp. 1 and A. sp. 2, which displayed identical food use but resided in shallow and deep zones of coarse and fine sediments, respectively, in Lake Hamana, Shizuoka Prefecture, Japan, were investigated by field removal and laboratory sediment-grain size selection experimentation. Following field manipulation, involving removal of both species, the distribution patterns of each were found to be similar in both control and manipulated quadrats, suggesting their differential habitat use patterns may be the outcome not of competition but of differing preferences for habitat characteristics. Results of a sediment-grain size selection experiment in the laboratory suggested a weak preference of A. sp. 2 for fine sediment, while A. sp. 1 showed no grain size preference. The observed difference in the distribution patterns between these two species, therefore, may possibly have resulted from, at least in part, a combination of differences in their preference for sediment grain size and other habitat characteristics such as water depth.     

Trophic interactions and habitat segregation between competing Daphnia species

Summary Two commonly coexisting species of Daphnia segregate by habitat in many stratified lakes. Daphnia pulicaria is mostly found in the hypolimnion whereas D. galeata mendotae undergoes diel vertical migration between the hypolimnion and the epilimnion. I examined how habitat segregation between these two potentially competing species might be affected by trophic interactions with their resources and predators by performing a field experiment in deep enclosures in which I manipulated fish predation, nutrient levels, and the density of epilimnetic Daphnia. The results of the experiment indicate that habitat use by D. pulicaria can be jointly regulated by competition for food from epilimnetic Daphnia and predation by fishes. Patterns of habitat segregation between the two Daphnia species were determined by predation by fish but not by nutrient levels: The removal of epilimnetic fish predators resulted in higher zooplankton and lower epilimnetic phytoplankton densities and allowed D. pulicaria to expand its habitat distribution into the epilimnion. In contrast, increased resource productivity resulted in higher densities of both Daphnia species but did not affect phytoplankton levels or habitat use by Daphnia. The two species exhibit a trade-off in their ability to exploit resources and their susceptibility to predation by fish. D. g. mendotae (the less susceptible species) may thus restrict D. pulicaria (the better resource exploiter) from the epilimnion when fish are common due to lower minimum resource requirements than those needed by D. pulicaria to offset the higher mortality rate imposed by selective epilimnetic fish predators. D. g. mendotae does not appear to have this effect in the absence of fish.     

Flexible migration of Japanese freshwater gobies Rhinogobius spp. as revealed by otolith Sr:Ca ratios

The migratory histories of six Rhinogobius spp., the cross‐band type (R. sp. CB), the large‐dark type (R. sp. LD), the dark type (R. sp. DA), the cobalt type (R. sp. CO), the orange type (R. sp. OR) and R. flumineus, were studied by examining strontium (Sr) and calcium (Ca) concentrations in their otoliths using wavelength dispersive X‐ray spectrometry on an electron microprobe. The Sr:Ca ratios in the otoliths changed both with the ontogenetic development and with the salinity level of the habitat. Most fishes had high Sr:Ca ratios around the otolith core in spite of the fact that those fishes live most of their lives in a freshwater environment. The high ratios in the otoliths were thought to be a physiological effect in those fishes. Thereafter, the Sr:Ca ratios changed remarkably along the life‐history transect, showing intraspecies and interspecies variations. The otolith Sr:Ca ratios of Rhinogobius sp. CB, R. sp. LD and R. sp. CO collected from three rivers connected to the sea were low around the core, subsequently increased sharply to the points 180–345 μm from the core and then decreased again towards the edge. They were thought to reflect the typical amphidromous life history. The R. sp. CO, however, remain in a brackish‐water environment after migration from the sea, while the other species showed typical amphidromous lives with complete freshwater residence after migration from the sea. The five species (R. sp. CB, R. sp. LD, R. sp. CO, R. sp. DA and R. sp. OR) collected above dams had never migrated to the sea, spending their whole life in a freshwater environment, although Rhinogobius species, except for the fluvial type, were thought to have an amphidromous life history according to previous studies. These species are thought to have a landlocked life cycle. The otolith Sr:Ca ratios of R. flumineus showed consistently low ratios towards the edge except for only around the core, although they were collected from a river connected to the sea. These species could have a fluvial life history corresponding to a previous study. The present study clearly suggests that the migratory histories of Rhinogobius spp. are highly different both within and between species and that they have flexible migratory patterns allowing them to utilize the full range of salinity during their life history.     

The role of microhabitat preference and social organization in determining the spatial distribution of a coral reef fish

Both habitat preferences and social organization can influence the spatial distributions of individuals. We explored effects of individual behavior and social organization on distributions of arc-eye hawkfish (Paracirrhites arcatus) in lagoons of French Polynesia. Analysis of habitat selectivity data obtained during surveys revealed that the most highly preferred microhabitat of arc-eye hawkfish was large Pocillopora coral with an open branching morphology. However, such corals were rare and most hawkfish occupied smaller, less preferred Pocillopora. Indeed, total abundance of Pocillopora explained nearly two thirds of the lagoon-wide variation in abundance of hawkfish and the derived relationship between the numbers of hawkfish and Pocillopora predicted 86% of the spatial variation in hawkfish abundance during subsequent surveys. In contrast, large, open-branched Pocillopora explained little of the spatial variation in abundance of hawkfish. Individual behavior and social organization significantly impacted use of the most highly preferred Pocillopora. During a colonization experiment set up outside hawkfish home ranges, all colonizers resided on the most highly preferred corals. Following addition of the most highly preferred Pocillopora corals to areas occupied by hawkfish, only the largest, socially dominant individuals obtained access to added corals, spending significantly more time and increasing both aggressive acts and prey attacks from these substrates. These results illustrate the importance of understanding the modulating effects of social behavior on habitat use and explain why most hawkfish individuals do not occupy their most preferred microhabitat type.     

Use of three types of stream-margin habitat by age-0 brown trout late in the growing season

The use of stream-margin habitat by age-0 salmonids has been studied, but differences in use among various types of habitat along stream margins has not been addressed. We described the nighttime use of habitat features by age-0 brown trout (Salmo trutta) among three types of stream-margin habitat late in the growing season (August–September) and assessed the extent to which use of habitat features within each type differed over the sampling period. Differences in water depths, water velocities, distances from shore, and substrate at the locations of fish along the margins of pools, the margins of riffles, and in backwaters were studied. Variation in habitat use also was observed during the study period as fish increased in length. Our observations are important considerations when developing habitat suitability criteria for assessment of instream-flow needs of age-0 brown trout.     

The effects of habitat manipulation on population distribution and foraging behavior in meadow voles

Individuals, free to choose between different habitat patches, should settle among them such that fitness is equalized. Alternatives to this ideal free distribution result into fitness differences among the patches. The concordance between fitnesses and foraging costs among inhabitants of different quality patches, demonstrated in recent studies, suggests that the mode of habitat selection and the resulting fitness patterns may have important implications to the resource use of a forager and to the survival of its prey. We studied how coarse scale selection between habitat patches of different quality and quitting harvest rate in these patches are related to each other and to fine scale patch use in meadow voles (Microtus pennsylvanicus). To demonstrate these relationships, we manipulated habitat patches within large field enclosures by mowing vegetative cover and adding supplemental food according to a 2×2 factorial design. We tracked vole population densities, collected giving‐up densities (GUDs, a measure of patch quitting harvest rate), and monitored the removal of seeds from lattice grids with 1.5 m intervals (an index of fine‐scale space use) in the manipulated habitat patches. Changes in habitat quality induced changes in habitat use at different spatial scales. In preferred habitats with intact cover, voles were despotic and GUDs were low, but increased with the addition of food. In contrast, voles in less‐preferred mowed habitats settled into an ideal free distribution, GUDs were high and uninfluenced by the addition of food. Seed removal was enhanced by the presence of cover but inhibited by supplemental food. Across all treatments, vole densities and GUDs were strongly correlated making it impossible to separate their effects on seed removal rates. However, this relationship broke down in unmowed habitats, where GUDs rather than vole density primarily influenced seed removal by voles. GUDs and seed removal correlated with predation on tree seedlings formerly planted into the enclosures, demonstrating the mechanisms between coarse‐scale habitat manipulations and community level consequences on a forager's prey.     

Temporal consistency in the spatial pattern of seed predation across a forest – old field edge

Seed predation is an important factor in determining the rate of tree establishment in abandoned agricultural land. Edges, through altered habitat use by small mammals, may influence the spatial pattern of forest regeneration in these successional sites. To determine the spatial pattern of seed predation across a forest-old field edge, we used a grid that began 30 m inside the forest and extended 60 m into the old field. Seed stations were placed at regular 10-m intervals and were monitored for removal of Acer rubrum seed for 50 d. This design was repeated over four years (1995–1998). Small mammal trapping was conducted in the final year of the study to determine the spatial pattern of seed predators within the site. Removal rates varied among the four years of the study with years of high and low removal rates. However, the spatial pattern of seed removal rate was similar in all years. Final survival ranged from 0.7–15.5% of seeds, with lower final survival in years with faster rates of seed removal (1996 and 1998). Seed removal rates and rates of discovery were greatest at the forest edge and decreased with distance into the old field. The number of seeds surviving to the end of the experiment also varied across the edge gradient, with highest survival at greater distances into the old field in low predation years. Seed removal rate covaried with spatial pattern of Peromyscus leucopus captures within the site. Seed removal and discovery was also higher under the exotic shrub Rosa multiflora, which may have provided cover for foraging seed predators. These indirect effects of edges on plant communities can potentially alter the rate and spatial pattern of tree invasion into disturbed lands and illustrate the importance of understanding plant-animal interactions in the context of habitat fragmentation.     

吉林蛟河针阔混交林树木生长的空间关联格局

以吉林蛟河21.12hm2(660m×320m)针阔混交林样地为对象,利用2009年和2014年森林生长观测数据,研究树木生长的空间自相关格局及其生境影响机制。在样地生境型划分结果的基础上,采用Ripley's L(r)函数分析不同生境型中树木种群空间分布特征;利用标记相关函数分析不同生境型中树木生长特征的空间关联格局。研究结果表明:(1)红松(生境型3:1—5m)、蒙古栎(生境型3:1—3m)、胡桃楸(生境型2:1—2m;生境型3:1—7m)、黄檗(生境型2:1—3m;生境型4:1—5m)、水曲柳(生境型3:1—2m;生境型4:1—2m)、瘤枝卫矛(生境型2:1—15m)在特定生境和空间尺度上呈随机分布,但空间格局仍以聚集性分布为主;其余10个物种则在全部0—30m尺度上呈聚集分布。(2)标记相关函数分析显示春榆、毛榛、色木槭、瘤枝卫矛和千金榆的径向生长至少在一个生境中表现出正相关格局;暴马丁香、胡桃楸、裂叶榆、瘤枝卫矛、水曲柳、紫椴、糠椴、毛榛、色木槭和白牛槭的径向生长至少在一个生境中表现出负相关格局;红松、黄檗、蒙古栎和簇毛槭的径向生长在全部尺度上均未检测到显著的空间关联格局。因此,不同树种径向生长的空间自相关特征不同,树种生长特征的空间关联格局具有明显的生境依赖性。     

Habitat correlates of the distribution and biomass of Seychelles' reef fishes

Synopsis Relationships between quantitative measures of habitat type and the biomass of Chaetodon, Scarus and Parupeneus species were investigated across 35 reef sites in the Inner Seychelles Group. Multiple regression was used to determine the proportion of variance in biomass between sites which could be explained by depth, exposure, vertical relief, topographic complexity, live coral cover, coral rubble cover, rock cover, sand cover, underlying carbonate substrate, underlying sand substrate, underlying rock substrate and an index of fishing intensity. A significant proportion of the variance in biomass was explained by habitat variables and the index of fishing intensity for 7 of 12 Chaetodon species (23–52% of variance explained), 3 of 6 Parupeneus species (33–40%), and 10 of 13 Scarus species (14–46%). Within genera, different groups of habitat variables explained the variance in biomass for different species and, of the variables studied, only the proportion of underlying sand substrate failed to explain a significant proportion of the variance in biomass for any species. Quantitative relationships between the biomass of Chaetodon and habitat were often in accordance with those suggested by previous studies of their ecology, life-history and distribution at other Indo-Pacific locations. However, the habitat associations of the Parupeneus and some Scarus species have not been studied at other locations and clearly warrant further investigation. It was concluded that habitat was an important determinant of the distribution of many Seychelles reef fishes, but that the habitat variables examined were rarely the most important determinant of biomass. However, the inclusion of a procedure to collect habitat data provided a useful means by which to reduce the unexplained variance associated with visual census biomass estimates and therefore improves the possibility of elucidating the effects of other factors on the biomass of Seychelles reef fishes.     

Direct and indirect effects of predation on mosquitofish behavior and survival

Predation can have strong direct and indirect effects on the behavior of prey. We investigated whether predation by chain pickerel (Esox niger) caused adult eastern mosquitofish (Gambusia holbrooki) to alter their habitat use and whether pickerel predation influenced survival of adult and neonate mosquitofish. The number of adult mosquitofish using the riskier of three habitats was lowest when two predators occupied the risky habitat, intermediate in the treatment with one predator, and highest when no predators occurred there. More mosquitofish neonates survived high predation treatments than treatments lacking pickerel. We conclude that pickerel predation causes adult mosquitofish to shift to refuge habitats. The pattern of neonate survival suggests that adult habitat use may create a refuge from cannibalism for neonate mosquitofish, resulting in higher neonate survival in treatments with more pickerel. Hence, pickerel predation has a direct effect on adult mosquitofish behavior and a strong indirect effect on neonate survival. Both interspecific and intraspecific predation can effect prey populations and can interact to produce important indirect effects.     

Abundance and Spread of the Invasive Red Algae, <Emphasis Type="Italic">Kappaphycus</Emphasis> spp., in Kane’ohe Bay,Hawai’i and an Experimental Assessment of Management Options

Several species of Kappaphycus were intentionally introduced into Kane’ohe Bay, Hawai’i in the 1970s. Subsequent research has demonstrated that these algae have spread rapidly throughout the bay and can be found in a variety of reef habitats overgrowing and killing corals. This study was conducted to (a) quantify Kappaphycus spp. abundance both spatially and temporally, and (b) investigate control options including manual removal and the use of biocontrol agents. Kappaphycus spp. distribution has increased in the bay over the period between surveys conducted in 1999 and 2002, with variation among reefs. The biomass of Kappaphycus spp. removed, and the amount of time required to manually remove them from the reef varied with habitat type, but in all cases amounted to at least 10 kg/m² requiring almost 2 person-hours to clear 1 m². Re-growth of the algae following their removal was rapid at most sites, likely due to the experimentally demonstrated ability of the algae to re-grow from minute attachment points and the low palatability of the algae to native herbivorous fishes. The native sea urchin, Tripneustes gratilla, reduced the biomass of Kappaphycus spp. in small experimental enclosures and may be a useful biocontrol agent. Because Kappaphycus spp. are still spreading in Kane’ohe Bay and can overgrow over 50% cover on some reefs, we recommend that rapid management action be taken to prevent further damage and spread to other Hawaiian coral reefs.     

Polyploid cytotypes and their habitat preferences inLycopodium clavatum

Morphological, cytological and ecological observations were made onLycopodium clavatum. Among 121 individuals from 26 populations studied 31 were of the diploid cytotype with 2n=68, 45 were of the triploid cytotype with 2n=102 and 45 were of the tetraploid cytotype with 2n=136. The populations were divided into three types: (1) the sole type—characterized by a single cytotype occupying an entire population, (2) the mixed type A—characterized by two or three cytotypes occupying together the same population, but each cytotype choosing different habitats, (3) the mixed type B—characterized by two or three cytotypes occupying together the same population and sharing the same habitat with each other. The mixed type B populations were found in the places of the early phase of secondary succession in a plant community. In the sole type and the mixed type A, the habitat preference for each cytotype was described as follows: the habitat for the diploid was in humid and shady places, that for the tetraploid was in open and sunny, unstable places, and that for the triploid was intermediate between the other two. Each cytotype can progress towards occupying their optimum habitat successively from the mixed type B population to the mixed type A population and finally reaching the sole type population.     

Forest fragmentation and plant reproductive success: a case study in four perennial herbs

We assessed the effects of habitat fragmentation on reproductive success in natural populations of four forest herbs with differing life-history traits and whose distribution patterns appeared to be negatively affected by decreased habitat size and/or increased isolation: Carex sylvatica, Galium odoratum, Sanicula europaea and Veronica montana. Our aims were to test (1) whether habitat size and isolation are positively correlated with population size and isolation, respectively, (2) whether plant reproductive success, a major component of plant fitness, is reduced in small and/or isolated populations when also accounting for differences in habitat quality (edaphic conditions, light intensity) and the effects of plant size, and (3) whether species with different life histories are affected differently. There were significant positive relationships between habitat and population size and between habitat and population isolation in some, but not all of the species. We mostly found no negative effects of small population size or isolation on reproduction. However, reproductive success was reduced in small populations of Sanicula, and this effect was independent of differences in plant size and environmental conditions. The reduced fecundity in small populations may be a consequence of the Allee-effect, a possible mechanism being pollen limitation. Furthermore, the proportion of flowering ramets was reduced in small and isolated populations of Galium, which may have been caused by changes in population structure. Lastly, we found some evidence for largely outcrossing, non-clonal species to be more sensitive to reductions in population size, at least in terms of their reproductive success.     

Rodent acorn selection in a Mediterranean oak landscape

Quercus suber, Quercus ilex and Quercus coccifera (Cork, Holm and Kermes oaks, respectively) are common evergreen oak species that coexist in the landscapes of the western part of the Mediterranean basin. Rodents are the main acorn predators and thus one of the main factors for understanding recruitment patterns in oaks. In this paper we analyse to what extent mice prefer acorns from one oak species over another in three oak species studied using acorn removal experiments and video tape recordings. Twenty labelled acorns from each of the three Quercus species (60 acorns) were placed in 40 cm×40 cm quadrats on each plot. Because selection might vary as a result of the vegetation context, we performed the trials in the five main vegetation types within the study area (four replicates in each vegetation type) in order to control for habitat influences on rodent acorn preferences (a total of 20 plots). The removal of 1,200 acorns occurred within 68 days. Mice removed 98.7% of the acorns. Q. ilex acorns were preferred over Q. suber and Q. coccifera in all vegetation types except in pine forest, where no acorn preferences were detected. Acorn removal rates differed with vegetation type, correlating positively with shrub cover. The distance at which acorns were displaced by rodents (mean =4.6 m±5.1 SD) did not differ between acorn species, but varied among vegetation types. Bigger acorns of Q. coccifera were selected only after Q. ilex and Q. suber acorns were depleted, while no size selection was detected for the latter two species. Thus, we conclude that rodents show preference for some oak acorns and that landscape context contributes significantly to rodent activities and decisions.     

Effects of compound eye-removal on the photoperiodic response of the band-legged ground cricket, Pteronemobius nigrofasciatus

The band-legged ground cricket Pteronemobius nigrofasciatus shows a clear photoperiodic response at 25°C with respect to the control of the induction of embryonic diapause. When crickets were reared under a short-day (LD 12 12) photoperiod and then transferred to a long-day (LD 16 8) photoperiod upon adult emergence, the adults mainly laid nondiapause eggs. However, adults maintained continuously under short-day conditions laid dispause eggs. When compound eyes were bilaterally removed after adult emergence, the crickets mainly laid nondiapause eggs, irrespective of the photoperiod. Thus, the adults completely lost their sensitivity to photoperiod after bilateral removal of their compound eyes. Unilateral removal of the compound eye also affected the crickets under a short-day photoperiod, and the incidence of diapause eggs was intermediate between that laid by intact adults and that laid by adults after the bilateral removal of compound eyes. The incidence of diapause eggs in sham-operated crickets was not significantly different from that in intact crickets under both sets of photoperiodic conditions. These results show that P. nigrofasciatus perceives the photoperiod through its compound eyes.     

The effect of invasive plant management on the rate of removal of vertebrate-dispersed fruits

Chrysanthemoides monilifera ssp. rotundata is an invasive plant in eastern Australia. It produces large quantities of fleshy fruits, which are dispersed by birds and mammals, and has the potential to alter ecological processes in native plant communities in several ways. Seed dispersal of native plants growing amongst C. monilifera could be decreased (if C. monilifera is effective in competing for limited seed dispersers), increased (if C. monilifera-infested vegetation supports more seed dispersers), or be unchanged (if there is sufficient separation in fruiting time or dispersal agents between the species, or if dispersers are not limiting). We compared the rates of removal of fruits of native plants (Monotoca elliptica and Elaeocarpus spp.) from experimental stations in C. monilifera stands, in uninfested coastal vegetation, and in vegetation from which C. monilifera had been eliminated with herbicide. The rate of removal of fruits differed between plant species and locations, but not between any of the habitat treatments. This may have resulted from temporal separation of peak fruit availability between M. elliptica and C. monilifera, and differences in fruit morphology and disperser assemblages between Elaeocarpus spp. and C. monilifera. We also measured removal of C. monilifera fruits from stations in C. monilifera stands and from where C. monilifera had been eliminated with herbicide. In the herbicide-treated habitat, removal of C. monilifera fruits was reduced. This may assist control efforts and suggests that, to reduce seed dispersal, dense (core) populations should be targeted in control programs.