Use of pheromone mimic to cause the disintegration and collapse of colonies of tent caterpillars (Malacosoma spp.)

The disruption of the trail-based communication system of eastern tent caterpillars (ETC) ( Malacosoma americanum ) and forest tent caterpillars (FTC) ( M. disstria ) by spraying host trees with a trail pheromone mimic caused the disintegration and collapse of young colonies. A 1-ppm formulation of 5β-cholestan-3-one or a control formulation was sprayed on trees either before or after eclosion of the caterpillars in the spring. For pre-eclosion trials, an average of 92% of the FTC colonies on control trees, but only 17% of colonies on treated trees consisted of viable, cohesive aggregates when survival was assessed 5–23 days post-spray. The remaining colonies had either completely disappeared or were reduced to small, disintegrated fragments. For the ETC, 100% of colonies on control trees and an average of 12% of colonies on treated trees consisted of cohesive aggregates inhabiting tents when survival was assessed 3–41 days post-spray. The remaining colonies were completely destroyed, reduced to scattered individuals, or to small, disintegrated, shelter-less fragments. For post-eclosion trials with the FTC in which colonies were sprayed during their first or second larval stadium, an average of 63% of individuals in control groups but only 7% in treatment groups were still on the sprayed trees 5–18 days post-spray. For the ETC, colonies were largely unaffected when trees were not sprayed until after the caterpillars had eclosed and established tents. For all trials, the loss of individuals on treated trees was largely attributable to the inability of dispersed and isolated first or second instar caterpillars to maintain secure purchase, causing them to fall from trees and perish. To our knowledge, this is the first study to investigate the potential of manipulating populations of pest species by interfering with a trail-based, chemical communication system.     

Roosting Ecology of the Tent‐Roosting Bat Artibeus watsoni (Chiroptera: Phyllostomidae) in Southwestern Costa Rica1

We described the plants used as roost resources by Artibeus watsoni in southwestern Costa Rica, assessed roost fidelity, and compared roosting ecology between two sites, Golfito and Corcovado, which vary in the degree of human influence. A total of 349 tents from 25 different plant species were used by A. watsoni as roosts; some plant species (e.g., Carludovica palmata, Asplundia alata, Heliconia imbricata and Calathea lutea) were modified into tents with significantly higher frequency than others. The highest tents above the ground were observed in Philodendron popenoei and Rhodospatha wendlandii, whereas tents in Philodendron grandipes and A. alata were significantly lower than any other species. Asplundia alata and R. wendlandii also had the highest frequency of leaves modified per plant. Fidelity of bats to tents was low, although bats used several tents intermittently within a restricted area. Males generally were more faithful to tents than females, although not significantly so. This observation, along with indirect evidence of leaf modification, suggests that males are primarily responsible for tent construction. The two study sites differed in the plants used for roosting and in tent fidelity. Bats in Corcovado used a greater variety of plant species for tent roosting, whereas bats in Golfito were more faithful, suggesting that roosting resources were scarcer at the latter site.     

Experimental study of foundation and development ofAnelosimus eximius colonies in the tropical forest of French Guiana

Summary Possibilities for new colony foundation inAnelosimus eximius (Theridiidae) were tested with isolated females (both with and without egg sacs) and with groups of individuals (groups from 150 to 250 spiders). Experimental groups were deposited in three different habitats: within the forest, on the forest edge (where natural colonies develop most frequently) and outside the forest (low savannah or areas cleared of vegetation, but in which plant life had started to grow back between the path and the forest edge).Isolated adult females had very low founding success: less than 13 % settled and spun a web; the presence of an egg sac provided by investigators was not an influencing factor. Webs of isolated females had the same architectures as those of colonies with several hundreds of individuals. This web was a horizontal sheet linked to a thick vertical network of threads.All groups of 150 to 250 spiders established colonies in appropriate habitats. The colonies outside the forest, and more than 90 % of the colonies along the forest edges successfully developed during the one month observation period. Conversely, 35 % of the colonies in the forest disappeared either a few days after being placed there, or one or two weeks after. In the latter case, spiders apparently left their webs, and all silk structures were left intact. No dead spiders were found in the webs.Average web surface areas increased in all colony types with age, except for those placed in the forest. In these colonies, the number of individuals decreased, and there were fewer egg sacs than in the colonies placed outside the forest.Results are discussed with regard to natural colony distribution along open paths and to the dispersive characteristics of this spider species.     

Thermal properties of the tent of early instar colonies of the eastern tent caterpillar, Malacosoma americanum (Lepidoptera: Lasiocampidae)

The extent to which the small tents of the early instars of Malacosoma americanum warmed when irradiated by sunlight was investigated by continuous electronic monitoring of field colonies for 137 colony-days. Tent temperatures exceeded the threshold for larval growth of 15 °C on 88–96% of the study days, exceeding in degree-minutes the ambient excess-over-threshold by a factor of approximately five. In still air, tents constructed by third instar caterpillars achieved greater temperature excesses over ambient than did a model of a tightly sealed glass house, but smaller tents and tents exposed to simulated wind did not perform as well. Tents of M. americanum warmed more rapidly and to a high temperature than silk nests of markedly different design constructed by other species.     

Mating dynamics of Scots pine in isolation tents

Seed orchards are forest tree production populations for supplying the forest industry with consistent and abundant seed crops of superior genetic quality. However, genetic quality can be severely affected by non-random mating among parents and the occurrence of background pollination. This study analyzed mating structure and background pollination in six large isolation tents established in a clonal Scots pine seed orchard in northern Sweden. The isolation tents were intended to form a physical barrier against background pollen and induce earlier flowering relative to the surrounding trees. We scored flowering phenology inside and outside the tents and tracked airborne pollen density inside and outside the seed orchard in three consecutive pollination seasons. We genotyped 5683 offspring collected from the tents and open controls using nine microsatellite loci, and assigned paternity using simple exclusion method. We found that tent trees shed pollen and exhibited maximum female receptivity approximately 1 week earlier than trees in open control. The majority of matings in tents (78.3 %) occurred at distances within two trees apart (about 5 m). Self-fertilization was relatively high (average 21.8 %) in tents without supplemental pollination (SP), but it was substantially reduced in tents with SP (average 7.7 %). Pollen contamination was low in open controls (4.8–7.1 %), and all tents remained entirely free of foreign pollen. Our study demonstrates that tent isolation is effective in blocking pollen immigration and in manipulating flowering phenology. When complimented with supplemental pollination, it could become a useful seed orchard management practice to optimize the gain and diversity of seed orchard crops.     

Reproductive success of Macrotermes bellicosus (Isoptera, Macrotermitinae) in two neighbouring habitats

The fungus-cultivating, mound-building termite Macrotermes bellicosus can reach high densities in African savannah habitats, whereas in forests it is comparatively rare and is only found in relatively open areas. Earlier studies in the Comoé National Park (Côte d'Ivoire, West Africa) suggested that this might be because ambient temperatures are lower in the forest than the savannah. Therefore, forests seem to be suboptimal habitats. During 3 consecutive years we measured relevant fitness parameters in both habitats to test this hypothesis. Colonies in the savannah had higher reproductive outputs. They reproduced annually, producing high numbers of offspring (alates), whereas forest colonies reproduced on average only once every 3?years and even then only low numbers of alates were produced. Annual growth of mound height, which can be regarded as an indicator of colony growth, varied considerably between individual colonies and years. Nevertheless, in two years the growth rate of mounds in the shrub savannah was higher than that of mounds in the gallery forest. Unexpectedly, survival probability as calculated by Kaplan Meier analysis was much lower for colonies in the shrub savannah than for colonies in the gallery forest. Using these data in a computer simulation we calculated lifetime reproductive success (LRS) for an average colony in both habitats. As LRS was much higher for colonies in the shrub savannah than in the gallery forest, these results confirmed our suggestion that the forest is a suboptimal habitat for M. bellicosus.     

Seasonal Variation in Seed Dispersal by Tamarins Alters Seed Rain in a Secondary Rain Forest

Reduced dispersal of large seeds into degraded areas is one of the major factors limiting rain forest regeneration, as many seed dispersers capable of transporting large seeds avoid these sites with a limited forest cover. However, the small size of tamarins allows them to use small trees, and hence to disperse seeds into young secondary forests. Seasonal variations in diet and home range use might modify their contribution to forest regeneration through an impact on the seed rain. For a 2-yr period, we followed a mixed-species group of tamarins in Peru to determine how their role as seed dispersers in a 9-yr-old secondary-growth forest varied across seasons. These tamarins dispersed small to large seeds of 166 tree species, 63 of which were into a degraded area. Tamarins’ efficiency in dispersing seeds from primary to secondary forest varied across seasons. During the late wet season, high dietary diversity and long forays in secondary forest allowed them to disperse large seeds involved in later stages of regeneration. This occurred precisely when tamarins spent a more equal amount of time eating a high diversity of fruit species in primary forest and pioneer species in secondary forest. We hypothesized that well-balanced fruit availability induced the movement of seed dispersers between these 2 habitats. The noteworthy number of large-seeded plant species dispersed by such small primates suggests that tamarins play an important, but previously neglected, role in the regeneration and maintenance of forest structure.     

Convergence in tent architecture and tent-making behavior among neotropical and paleotropical bats

Fifteen species of neotropical and three species of paleotropical bats are known either to roost in or to make tents in over 80 species of vascular plants. We summarize the current knowledge of bat-tent architecture, report two new styles of tents (conical and apical) from the Paleotropics, compare the similarity in tents constructed, or used, by neotropical and paleotropical bats, and consider possible functions of tents. Seven styles of tents are known from the Neotropics, three (conical, palmate umbrella, and apical tents) are known from both the Neo- and the Paleotropics, and one (stem tent) is unique to the Paleotropics. In the Neotropics tent-roosting and/or tent-making appears to be a behavior unique to the diverse microchiropteran family Phyllostomidae (subfamily Phyllostomatinae: tribe Stenodermatini), and in the Paleotropics two members of the megachiropteran family Pteropodidae and one member of the microchiropteran family Vespertilionidae are known to construct or roost in tents. Despite the variety of plant taxa used by bats in tent construction, there appears to be a limited number of different leaf forms that can be altered by bats and used as tents. We suggest that the similarity in tent architecture observed among the neotropical and paleotropical bats is a consequence of convergence in leaf morphology among forest understory plants. The congruence in tent-making/roosting behavior observed in members of the Stenodermatini and the Pteropodidae (genusCynopterus) suggests a phylogenetic influence on these behaviors. The similarity in tent-making and/or tent-roosting behavior and life-history traits (small, <70 g, mostly foliage-roosting frugivores) among these divergent neotropical and paleotropical taxa supports a convergence hypothesis in which members of these groups have become ecological equivalents. Although actual tent-making has been observed in only one bat species to date, we suggest that the principal selective force leading to the evolution of tent-making is a polygynous mating system whereby males construct tents to gain access to females. Tents in turn provide resources that offer protection from predators and inclement weather.     

Paramecium Transport by Land Snails

SYNOPSIS. Field observations and experiments in a tropical forest revealed that Paramecium multimicronucleatum and other small aquatic organisms are transported between Heliconia flowers by terrestrial snails of the genus Caracolus . It is probable that dispersal is readily accomplished in tropical forests, and that the presence or absence of Paramecium in a given area therefore is determined by biological interactions.     

犬蝠夜栖息地及夜栖息巢特征的初步研究

<正>大多数种类的蝙蝠不会整个晚上都进行觅食,通常在觅食期间有一段长短不一的时间停留在临时地休息,此为夜栖息行为(Hatfield,1937;Krutzsch,1954;Barbour and Davis,1969;Kunz,1973,1974;Hirshfeld et al.,1977)。蝙蝠在夜栖息地进食(Vaughan,1976;Funakoshi and Maeda,2003)、休息并消化食物(Brigham,1991;Funakoshi and Maeda,2003),甚至社会交流(Kunz,1982;Kunz and Lumsden,2003)。不同种类的蝙蝠     

海南岛尖峰岭次生热带山地雨林树种间的联结动态

应用方差检验法和基于２＊２联列表的分析手段,对海南岛尖峰岭热带山地雨林采伐后２５－３５年次生群落２４００ｍ＾２固定样中胸径≥７．０ｃｍ林木的种间联结动态进行了研究,结果如下：１）群落内的树种总体呈正联结,但未达到显著水平。联结指数Ｖ界于１．００－１．２１之间,接近无联结假设条件下的Ｖ值（Ｖ＝１）,证实了作者关于“种的分布相对独立”的假说;２）种间联结的比例和强度随演替进程而下降,群落朝种间无联结中     

Traditional land use associated with swidden agriculture changes encounter rates of the top predator, the army ant, in Southeast Asian tropical rain forests

We examined the effect of traditional swidden agriculture on biodiversity using the litter arthropod top predator, the army ant Aenictus (Hymenoptera: Formicidae) as an indicator species in and around an intact tropical rain forest in Sarawak, Borneo, Malaysia. We compared the encounter rates with Aenictus colonies among five forest types: continuous primary forest, isolated primary forest, old secondary forest (>20 years elapsed after abandonment of the fields), young secondary forest (5 years after abandonment), and new fallow (2 years after abandonment) by intensive area searching in 2003 and 2005. In total, seven Aenictus species (15 colonies) and six Aenictus species (11 colonies) were encountered in 2003 and 2005, respectively. The encounter rates were the highest in continuous and isolated primary forests, intermediate in old and young secondary forests, and the lowest in new fallow. Year and the interaction between year and forest type were not significant. That is, abundance of top predators, which is rare and likely to be vulnerable to disturbance, has never fully recovered even 20 years after the termination of cultivation. We discuss forest management strategies to sustain biological diversity.     

Natural history and foraging behavior of the carpenter ant Camponotus sericeiventris Guérin, 1838 (Formicinae, Campotonini) in the Brazilian tropical savanna

Camponotus sericeiventris is a polymorphic ant living in populous colonies at tropical forests and cerrado formation. This study provides a detailed account of the natural history and foraging biology of C. sericeiventris in cerrado at Ecological Station of Panga, Southeast of Brazil. The nest distribution according to vegetation physiognomies, activity rhythm, diet, and foraging patterns were described. Results showed that nests occur inside dead or live trunks, and also in branches of soft wood at cerradão and gallery forest physiognomies (approximately 1 nest/100m²), but not in the mesophytic forest. Ant activity is correlated with temperature and humidity. There is overlap in the foraging area among neighbor colonies (as far as 28 m) without evidence of agonistic interactions. Foragers leave the nest independently or in groups and frequently searched for food individually. Workers are generalistic feeders visiting flowers and extrafloral nectaries, attending Hemiptera (aphids and membracids) and Lepidoptera (Lycaenidae larvae), collecting seeds and fruits, and hunting for live preys as well as scavenging for dead animals. The great number of interactions with different plant and animals suggests that this species has an important participation in the interaction web in this environment.     

Insect Herbivory and Leaf Disease in Natural and Human Disturbed Habitats: Lessons from Early‐Successional Heliconia Herbs

The interaction of plants with insect herbivores and fungal pathogens can affect community dynamics, but there is little information on how this antagonistic interaction may be altered in human‐disturbed tropical systems. We examined whether the amount and quality of foliar damage on the pioneer herbs Heliconia latispatha and Heliconia collinsiana are distinct on road edges and secondary riparian vegetation compared with natural gaps in continuous forest (controls) in Mexico. We also investigated some physical and biological mechanisms that may jointly explain such differences. The overall insect damage in H. latispatha was similar between road edges and natural forest gaps (8.0% vs. 7.2% of leaf area). Damage by caterpillars, however, decreased from 4.2 percent in forest gaps to 0.5 percent on road edges, whereas damage by leaf‐cutting ants increased from 0 to 5.8 percent. In secondary riparian vegetation, where none of the leaves sampled were attacked by ants, overall herbivore damage in H. collinsiana was less than half that observed in forest gaps (3.0% vs. 6.7%), and driven mainly by differences in caterpillar damage (2.5% vs. 6.2%). By contrast, attack by leaf fungal pathogens was two to three times greater in both human‐disturbed habitats than in gaps (8.2–9.6% vs. 3.7–4.2%). Potential mechanisms underlying these differences involved human‐induced shifts in air and soil temperature driven by greater light availability, as well as changes in relative humidity, leaf toughness, foliar condensed tannins, and local abundance of herbivores. Our results indicate that human disturbance alters insect herbivory and may increase proliferation of leaf disease. Abstract in Spanish is available in the online version of this article.     

The dynamics of tent‐roosts in the palm Sabal mauritiiformis and their use by bats in a montane dry forest

Tent‐making bats modify leaves to build refuges. Leaf modification involves energetic and defense costs that should be balanced by the benefits of tent‐roosting. The alteration of the leaf's vascular system reduces the tent's life expectancy, so to obtain a benefit, bats are expected to use tents regularly as long as they remain functional and not modify more leaves than necessary. Over 2 yr, we documented the dynamics of tent construction and use by Uroderma convexum and other bat species in the palm Sabal mauritiiformis in a Colombian transitional dry forest. We also assessed tent condition and compared it to nonmodified leaves of approximately the same age in focal palms. Probability of tent use by U. convexum varied between 57 percent during a reproductive period and 4 percent outside of this period. Bats cut the main vein of folioles, partially affecting water transport in the leaf. However, there were no differences between tents and nonmodified leaves in deterioration scores or deterioration rates over 1 yr. During 2 yr, 48 tents were lost for different causes, but this loss was balanced by the construction of 51 new tents. Thus, bats maintained an excess of usable tents. Palm leaves are long‐lived and seem preadapted to sustain damage and remain viable, particularly in species growing in dry environments. We present several hypotheses to explain the advantage of maintaining a tent surplus.     

湘南典型次生林粗木质残体生物量、碳储量和养分特征

对九龙江森林公园次生常绿阔叶林粗木质残体(CWD)进行量化研究,了解亚热带典型次生林CWD的本底数据。以九龙江森林公园典型天然次生林中的6个20m×20m的标准样地为对象,调查并分析样地内不同分解等级CWD的生物量、碳储量和养分特征变化。九龙江森林公园亚热带典型次生林的CWD储量在2.8—30.4t/hm~2之间,碳储量在6.10—6.75t/hm~2之间,大量营养元素(N、P、K、 Ca、 Mg)含量相对稳定,化学计量变化不显著,微量营养元素中Pb与Cd元素含量随着分解等级的增加而增加。九龙江森林公园亚热带典型次生林的CWD储量在亚热带常绿阔叶林中处于中等水平,CWD主要以分解中后期的倒木为主,反映出该次生林处于中幼龄林阶段,具有较高的碳储量,养分含量相对稳定,并表现出Pb与Cd在CWD中积累的现象,在中度分解和重度分解的CWD中Pb含量分别增加了62.65%和69.88%,Cd含量则分别增加了33.33%和100%,其内在机理有待进一步深入研究。研究结果有助于进一步了解CWD如何参与森林生态系统养分循环、重金属积累等生态过程,比较不同林分干扰历史下CWD储量、分布及养分特征的异质性...     

Plant and Litter Influences on Earthworm Abundance and Community Structure in a Tropical Wet Forest1

Plant communities differ in species composition and litter input. To examine the influence of plant species on the abundance and community structure of soil fauna, we sampled earthworms in areas close to and away from the bases of Dacryodes excelsa and Heliconia caribaea, two distinct plant communities within a tropical wet forest in Puerto Rico. We also carried out a litter manipulation experiment to examine the short–term responses of earthworms to litter removal and litter addition treatments. We found that: (1) the density and biomass of both soil–feeding endogeic and litter-feeding anccic worms did not differ between areas close to and away from Dacryodef trees (in contrast, the density and biomass of anecic worms was higher in areas away from Heliconia plants despite the lack of differences for endogeic worms); and (2) total dry weight of earthworms tended to be higher in the litter addition treatment than in the control within the Heliconia community. Our results suggest that Heliconia caribaea has a strong negative influence on anecic earthworms and that earthworms in the Heliconia community are more sensitive to litter input than in the Dacryodes community.     

New national and regional bryophyte records, 31

Abstract

Seasonal patterns in growth and dynamics of 13 epixylic bryophyte species (six liverworts and seven mosses) were studied within permanent plots in the ?ofínský prales old-growth forest in south-eastern Bohemia, Czech Republic. Transparencies were used to record positions and cover of bryophyte colonies within each plot twice a year (in spring and autumn) for periods of 1–4 years. Percentage growth of species populations and growth dynamics of their colonies were analysed in order to identify seasonality in their growth. Establishment of bryophyte colonies and their expansion, as well as pair-wise overgrowth of adjacent colonies of different species were compared in order to identify competitive interactions between bryophyte species. Bryophytes grew faster during the winter season (October–April) than during summer, and the various species did not differ in their percentage growth. The growth dynamics of bryophyte colonies was highly seasonal and the species differed in their dynamics pattern. The expansion and retreat (local extinction) of bryophyte species were greatest in winter, and the stability of colonies was, therefore, higher in summer. Interspecific competition among the species studied appears to be low.     

Roosting Behavior of Colonial and Solitary Flying Foxes in American Samoa (Chiroptera: Pteropodidae)1

We examined characteristics of roosting sites utilized by two flying fox species (Pteropus tonganus and P. samoensis) in American Samoa. The colonial roosting sites of P. tonganus were observed over a ten‐year period, including two years when severe hurricanes devastated bat populations and destroyed roost trees. Prior to the hurricanes, roosts were located on cliff faces above the ocean or steep mountainsides, locations that were either inaccessible to people or in protected areas where hunting was not allowed. In the years immediately following the hurricanes, P. tonganus colonies split into smaller groups that moved frequently to different locations. Four years after the second hurricane, colonies had coalesced and returned to many of the traditional roosting sites used before the hurricanes. Common tree species in upland and coastal forest were selected as roosts. The isolated locations selected for P. tonganus roosts were apparently the result of hunting pressure on the colonies. The solitary roosts of P. samoensis were observed during 29 months. Roosting bats were well concealed and hard to detect within the forest; even bats on exposed branches were cryptic. Mature primary forest was favored as roosting habitat. Individual bats used specific branches or trees as roosts and returned to them for up to 29 months. Unlike P. tonganus, people did not alarm roosting P. samoensis easily and some roosts were located near houses and along roads.     

The potential availability of roosting sites for lesser short‐tailed bats (Mystacina tuberculata) on Kapiti Island,New Zealand: Implications for a translocation

Abstract

Lesser short‐tailed bats (Mystacina tuberculata) have recently been translocated to Kapiti Island in an attempt to form a new population of this threatened species. However, the island's vegetation is regenerating, and there was doubt that the forests provided enough large trees with cavities for bats to roost in. This study measured the availability of tree‐trunk cavities of the right size for potential roost sites on Kapiti Island, and assessed if habitat restoration would be required to increase the translocation's chance of success. first, trees with cavities accessible to us were sampled in six of Kapiti Island's forest types. Size variables known to affect roost site selection by lesser short‐tailed bats at the tree and cavity level were measured. Trees were classified as containing cavities that could potentially provide suitable roosts if their values for all variables measured fell within the range of roosts used by lesser short‐tailed bats in natural populations. Roosts were classified as suitably sized for solitary bats or for colonies, using measurements from both types of roosts in natural populations. Second, the density of these potential roost cavities was calculated. Cavities of a size potentially suitable for colonies were found in four of the six forest types at densities ranging from 3.2 ± 3.2 Se to 52.4 ± 14.0 trees per ha. density of potential solitary roosts was much higher. Not all potential cavities will be suitable because they may be damp, poorly insulated, or have an unsuitable microclimate. Nevertheless, our estimates indicated that the two most extensive forest types each contained thousands of potential cavities of a size suitable for colonies of lesser short‐tailed bats. In addition, there were tens of thousands of cavities large enough to shelter solitary bats. Roost habitat restoration appears unnecessary to assist translocated Mystacina tuberculata on Kapiti Island.