An introduction experiment of an herbivorous lady beetle: Characteristics of the adult population

In May 1971, 45 adults of an herbivorous lady beetleEpilachna niponica (Coleoptera: Coccinellidae) from Asiu Experimental Forest were introduced into a botanical garden of Kyoto University, where is 10 km south of the southern limits of its distribution with being 3–5°C warmer than the original site. The introduced population of the lady beetle was thus investigated from 1975 to 1981. Mark-release-recapture experiments were applied to individual adult beetles, to estimate population size and daily survival rate. Overwintering adults emerged from hibernation around early April, reaching peak numbers in late April to early May, then gradually declined to late June. No adults remained at the end of June. Adult survival was maintained at a high level to early May, and declined consistently until late in the reproductive season. New adults began to emerge in late June and quickly reached a peak in early July; thereafter they decreased in number and had entered hibernation by late October. In spite of seasonally deteriorating food resources and heat stress in summer, new adults showed moderately high survival during the inimical period. New adults which emerged later in the season tended to be smaller in body size than those that emerged early. The proportion of females in the new adult population gradually increased throughout the pre-hibernating period, suggesting that male-biased mortality occurred during this period. When compared to the source population, the introduced population had a higher rate of population growth. Coupled with the improved population growth, heavy leaf damage during the larval period suggested that intensive intraspecific competition was most likely to occur among larvae in the introduced population.     

Restricted movement by mottled sculpin (pisces: cottidae) in a southern Appalachian stream

1. We used direct observation and mark‐recapture techniques to quantify movements by mottled sculpins (Cottus bairdi) in a 1 km segment of Shope Fork in western North Carolina. Our objectives were to: (i) quantify the overall rate of sculpin movement, (ii) assess variation in movement among years, individuals, and sculpin size classes, (iii) relate movement to variation in stream flow and population size structure, and (iv) quantify relationships between movement and individual growth rates. 2. Movements were very restricted: median and mean movement distances for all sculpin size classes over a 45 day period were 1.3 and 4.4 m respectively. Nevertheless, there was a high degree of intrapopulation and temporal variation in sculpin movement. Movement of juveniles increased with discharge and with the density of large adults. Movement by small and large adults was not influenced by stream flow, but large adults where more mobile when their own density was high. Finally, there were differences in the growth rates of mobile and sedentary sculpins. Mobile juveniles grew faster than sedentary individuals under conditions of low flow and high density of large adults, whereas adults exhibited the opposite pattern. 3. Our results support the hypothesis that juvenile movement and growth is influenced by both intraspecific interactions with adults and stream flow. In contrast, adult movement appears to be influenced by competitive interactions among residents for suitable space. The relationship between movement and growth may provide a negative feedback mechanism regulating mottled sculpin populations in this system.     

Strong “bottom‐up” influences on small mammal populations: State‐space model analyses from long‐term studies

“Bottom‐up” influences, that is, masting, plus population density and climate, commonly influence woodland rodent demography. However, “top‐down” influences (predation) also intervene. Here, we assess the impacts of masting, climate, and density on rodent populations placed in the context of what is known about “top‐down” influences. To explain between‐year variations in bank vole Myodes glareolus and wood mouse Apodemus sylvaticus population demography, we applied a state‐space model to 33 years of catch‐mark‐release live‐trapping, winter temperature, and precise mast‐collection data. Experimental mast additions aided interpretation. Rodent numbers in European ash Fraxinus excelsior woodland were estimated (May/June, November/December). December–March mean minimum daily temperature represented winter severity. Total marked adult mice/voles (and juveniles in May/June) provided density indices validated against a model‐generated population estimate; this allowed estimation of the structure of a time‐series model and the demographic impacts of the climatic/biological variables. During two winters of insignificant fruit‐fall, 6.79 g/m² sterilized ash seed (as fruit) was distributed over an equivalent woodland similarly live‐trapped. September–March fruit‐fall strongly increased bank vole spring reproductive rate and winter and summer population growth rates; colder winters weakly reduced winter population growth. September–March fruit‐fall and warmer winters marginally increased wood mouse spring reproductive rate and September–December fruit‐fall weakly elevated summer population growth. Density dependence significantly reduced both species' population growth. Fruit‐fall impacts on demography still appeared after a year. Experimental ash fruit addition confirmed its positive influence on bank vole winter population growth with probable moderation by colder temperatures. The models show the strong impact of masting as a “bottom‐up” influence on rodent demography, emphasizing independent masting and weather influences; delayed effects of masting; and the importance of density dependence and its interaction with masting. We conclude that these rodents show strong “bottom‐up” and density‐dependent influences on demography moderated by winter temperature. “Top‐down” influences appear weak and need further investigation.     

Ontogenetic shifts in drift periodicity and benthic dispersal in elmid beetles

1. There is a paucity of information on ontogenetic changes in the dispersal of benthic invertebrates, which is an important aspect of their ecology. This study quantifies ontogenetic changes in diel periodicity in drift, and in upstream–downstream dispersal on the substratum for Elmis aenea, Oulimnius tuberculatus, Esolus parallelepipedus and Limnius volkmari (Coleoptera: Elmidae). Three drift nets were emptied every 3 h over 24 h in each month (October 1965–December 1968) at two contrasting sites: one in a deep section with abundant macrophytes, the other in a shallow stony riffle. Comparisons of periodicity between life‐stages of the same species were limited to months when numbers in the drift were highest. Dispersal was evaluated in six experimental stream channels, placed above the stream, with initial numbers of each life‐stage varying from 20 to 80. 2. Drift numbers were always highest at night with few or no animals in the day samples. Ontogenetic shifts in diel periodicity were similar for all four species. Drift catches were similar throughout the night for the early and intermediate larval instars and for mature adults, but were highest in the early hours of the night with a gradual decline thereafter for later larval instars and immature adults. These patterns were unaffected by a severe spate, even though drift numbers increased considerably. 3. Dispersal was density‐independent; the number of dispersing animals was a constant proportion of the initial number for each life‐stage. The relationship between dispersal distance and the number of animals travelling that distance was well described by an inverse power function. Median and maximum distances (m day^?1) were estimated for each life‐stage. 4. Ontogenetic shifts in dispersal in the stream channels matched those shown in diel drift periodicity. For all four species, the later larval instars and immature adults showed little movement in either direction, whereas early and intermediate larval instars and mature adults dispersed predominantly upstream, adults travelling further than any other life‐stage. 5. Ontogenetic shifts in diel drift periodicity and dispersal were related to seasonal changes in drift density and critical periods in the life cycle. Such shifts have not been quantified in other stream invertebrates, but should be considered when evaluating the role of dispersal in their population dynamics and their colonization ability.     

Population structure and sexual maturity of Aegla castro (Decapoda,Anomura), an endemic freshwater crab from Brazil

Specimens of Aegla castro Schmitt, 1942 were monthly sampled from June 2012 to May 2013 from Couro stream (23°57′15″S 51°06′00″W), located in the Upper Paraná river region, southern Brazil. Population structure, morphometric and functional maturity were analyzed. Allometric growth analysis on chela dimension versus carapace length (CL) was employed to recognize juveniles and adult individuals. Two sequential groups of adult males (morphotypes I and II) were recognized according to the state of development of the pair of claws. The CL where 50% of the population of individuals are adults (CL₅₀) was used to estimate the size at the onset of morphometric maturity. Males attain morphometric maturity at same size class of females (8.0–9.0 mm CL). Males and females are heterochelous and they often show the left chela more developed. The reproductive period was extended from June to September 2012 and April to May 2013 (six months) with record of 22 ovigerous females. The recruitment occurred in the months following the reproductive period, with higher records in October and December 2012. All the information gathered here should be useful to better understand the biology of the species studied.     

Reproductive and larval cycle of the scallop Argopecten purpuratus (Ostreoida: Pectinidae), during El Niño-La Niña events and normal weather conditions in Antofagasta, Chile

Seasonality, amplitude, and magnitude of spawning events were determined for Argopecten purpuratus in the La Rinconada marine reserve, Antofagasta, Chile, between December 1995 and January 2004. During the same period, samples of scallop larvae were obtained in vertical plankton hauls recovered within this reserve in an area routinely exposed to circular, gyre-like currents which helped retain the larvae within the bay. The reproduction of this population in normal or cool (e.g. "La Ni?a", 1998-2000) years occurred throughout the year, with a more active period between September and April, declining in June and August; this contrasted with the warmer "El Ni?o" oceanographic period of 1997-98 in which reproductive activity was more intense and prolonged throughout the entire year. The reproductive events in this population were mostly synchronous, although one asynchronous period occurred each year following the more intense March to May spawnings. This reproductive activity generated a continuous presence of larvae in the area in which no strict relation could be found between the intensities of spawning and numbers of larvae in the water. Larval presence was, however, generally correlated with active spawning periods. Important increases in larval numbers recorded at the end of 1999 and the beginning of 2003 were correlated with census data showing a higher percentage presence of broodstock over 90 mm in shell length during these years. An adequate stock of this size class is needed for a successful seed capture program in the reserve (for mass culture).     

Linking warming effects on phenology,demography, and range expansion in a migratory bird population

Phenological changes in response to climate change have been recorded in many taxa, but the population‐level consequences of these changes are largely unknown. If phenological change influences demography, it may underpin the changes in range size and distribution that have been associated with climate change in many species. Over the last century, Icelandic black‐tailed godwits (Limosa limosa islandica) have increased 10‐fold in numbers, and their breeding range has expanded throughout lowland Iceland, but the environmental and demographic drivers of this expansion remain unknown. Here, we explore the potential for climate‐driven shifts in phenology to influence demography and range expansion. In warmer springs, Icelandic black‐tailed godwits lay their clutches earlier, resulting in advances in hatching dates in those years. Early hatching is beneficial as population‐wide tracking of marked individuals shows that chick recruitment to the adult population is greater for early hatched individuals. Throughout the last century, this population has expanded into progressively colder breeding areas in which hatch dates are later, but temperatures have increased throughout Iceland since the 1960s. Using these established relationships between temperature, hatching dates and recruitment, we show that these warming trends have the potential to have fueled substantial increases in recruitment throughout Iceland, and thus to have contributed to local population growth and expansion across the breeding range. The demographic consequences of temperature‐mediated phenological changes, such as the advances in lay dates and increased recruitment associated with early hatching reported here, may therefore be key processes in driving population size and range changes in response to climate change.     

Individual behaviour and resource use of thermally stressed brook trout Salvelinus fontinalis portend the conservation potential of thermal refugia

Individual aggression and thermal refuge use were monitored in brook trout Salvelinus fontinalis in a controlled laboratory to determine how fish size and personality influence time spent in forage and thermal habitat patches during periods of thermal stress. On average, larger and more exploratory fish initiated more aggressive interactions and across all fish there was decreased aggression at warmer temperatures. Individual personality did not explain changes in aggression or habitat use with increased temperature; however, larger individuals initiated comparatively fewer aggressive interactions at warmer temperatures. Occupancy of forage patches generally declined as ambient stream temperatures approached critical maximum and fish increased thermal refuge use, with a steeper decline in forage patch occupancy observed in larger fish. These findings suggest that larger individuals may be more vulnerable to stream temperature rise. Importantly, even at thermally stressful temperatures, all fish periodically left the thermal refuge to forage. This indicates that the success of refugia at increasing population survival during periods of stream temperature rise may depend on the location of thermal refugia relative to forage locations within the larger habitat mosaic. These results provide insights into the potential for thermal refugia to improve population survival and can be used to inform predictions of population vulnerability to climate change.     

Life cycle and population dynamics of Annina mesopotamica (Ahmed), (Isopoda, Flabellifera) in the Shatt Al-Arab Region, Basrah, Iraq

A population of the intertidal, ovoviviparous, cirolanid isopod Annina mesopotamica was studied at the Al-Chibassy tributary of the Shatt Al-Arab river from 14 May 1973 to 29 April 1974, and at the Garmat-Ali river of the Shatt Al-Arab, Basrah, Iraq from 5 November 1984 to 30 June 1986. Population density varied between 128 to 5760 individuals m^–2 with a mean of 1218 m^–2. Highest numbers occurred between June and September. Breeding extended for most of the year except November/January to February/March, although ovigerous females were present throughout the year. The incubation period varied with season, and was ca. 2 weeks during the warmest period, and about a month at lower temperatures. Egg numbers varied between 4 to 66 with mean 24. Brood size was linearly proportional to female size. The size frequency distribution of the population was polymodal with a predominance of females over males. Four different types of growth curves were found: exponential, concave, convex, and intermediate between concave and convex. Growth rate varied between 0.63 and 2.19 mm month^–1. Mortality was higher among summer cohorts. Life span varied between 5 and 11 months.     

Modeling population dynamics and conservation of arapaima in the Amazon

To promote understanding of fish population dynamics in tropical river-floodplains, we have synthesized existing information by developing a largely empirical population model for arapaima (Arapaima sp.). Arapaima are characterized by very large bodies, relatively late sexual maturity, small clutches, and large parental investment per offspring, and their populations are overexploited and even declining due to overfishing. We used unparalleled time series data on growth, reproduction, catch-at-age, and size-class abundance estimates for a population that has increased several-fold and undergone drastic changes in fishing practices in the Amazon, Brazil. Model population numbers were close to observed numbers, with generally low mean absolute percentage errors for juveniles (16%), adults (30%), and catch (18%). In using the model to test ecological hypotheses and to investigate management strategies, we found the following: (1) Annual recruitment is directly and positively related to spawner abundance, and it appears to be density-compensatory following a Beverton–Holt relation (R ² = 0.85). (2) Fishing-selectivity of arapaima caused by use of harpoons and gillnets can lower yield potentials dramatically through removal of the faster-growing individuals of the population. That is in part because fewer individuals live long enough to reproduce and survivors take longer to reach reproductive age. (3) Arapaima populations can sustain annual catches of up to 25% of the number of adults in the population the previous year if minimum size (1.5 m) and closed season (December–May) limits are met. (4) When 25% of the number of adults in the population the previous year is harvested under a 1.6 m minimum size limit of catch, catches are slightly smaller but abundance of adults in the population is considerably greater than under a 1.5 m limit. These findings can be used in ongoing management initiatives, but caution is needed because of present biological and ecological uncertainty about these fishes.     

Seasonal aspects of the invertebrate fauna of three species of plants and rock surfaces in a small stream

Macroinverbrates associated with three species of aquatic plants and those on rock surfaces in a stream were collected every two weeks from late May to late November. Some animals appeared to use all plants opportunistically as substrates from which food sources could be better exploited throughout the season. Others, usually of minor numerical importance, strongly differentiated between plant species and appeared to find the resources that they may require on only one plant and only at specific times of the year. Myriophyllum alterniflorum supported the highest density of invertebrates but numbers per unit surface area fluctuated widely throughout the season. Numbers of individuals on exposed rocks were remarkably constant and animals that dominated there were usually different from those on plants. Patterns in both total individuals and numbers of individuals within different taxa indicate that seasonal variation in phytomacrofauna in streams is significant and should be considered in the design of future studies.     

Life cycle of an endangered riffle beetle,Leptelmis gracilis Sharp (Coleoptera: Elmidae), in the Hiikawa River system,Shimane prefecture,Japan

We studied the life cycle of the riffle beetle Leptelmis gracilis Sharp, 1888 from a population located in a river stream with lotic environments. Samples were collected monthly, between September 2018 and August 2019, from a tributary of the Hiikawa River in Izumo city, Shimane Prefecture, Honshu, Japan. Larvae were separated into five distinct groups based on size. The first and last instar larval sizes were identified through rearing methods. From these results, we determined that the larval stage of this species consists of five instars. From the monthly evaluations, the number of individuals corresponding to each instar period suggested that last-instar larvae were dominant in May and that new adults emerged from July to August. Landing and pupation were estimated to occur from May to June. Monthly observations revealed that mature eggs were present in the female abdomen from April to June, as well as from August to September. It is, therefore, predicted that overwintering adults mainly oviposit from spring to early summer, while new adults oviposit from late summer to early autumn.     

Comparative Ecology of the Crayfishes Orconectes rusticus rusticus and Cambarus tenebrosus in Doe Run,Meade County,Kentucky

The ecology and life histories of Orconectes rusticus rusticus (GIRARD) and Cambarus tenebrosus HAY were investigated in a spring stream, Doe Run, Meade County, Kentucky, from September 1962 through September 1964. Differences in ecology of these species were most clearly seen in their habitat preferences and distributions in the stream, their feeding habits, responses to temperature, and infestations by an harpacticoid copepod Attheyella carolinensis CHAPPUIS, and in other life history phenomena, particularly with regard to reproduction and growth. Cambarus tenebrosus was most abundant in the constant temperature areas of the headwaters of Doe Run. Orconectes r. rusticus was found only in the lower three-fourths of the stream. Water temperatures in the headwater area may have been too low (12 — 14 C) for optimal growth of the crayfish had it existed there. Adults of C. tenebrosus were primarily hypogean, but young and subadults frequented the open stream environment. Orconectes r. rusticus was primarily an open stream inhabitant, and was sympatric with C. tenebrosus subadults and young in the downstream areas. When C. tenebrosus occurred in the open environment, it was most abundant in association with vegetation, and hence, was more heavily infested with A. carolinensis than O. r. rusticus. Detritus, mainly from fallen leaves and marl grazings, apparently formed the most important component of the diet of O. r. rusticus. Vascular plants, mainly fallen leaves from the riparian vegetation, constituted the main portion of the diet of C. tenebrosus; filamentous algae were widely used where and when they were present. Orconectes r. rusticus eggs hatch in May. These hatchlings become mature in 15 months and females oviposit after 22 – 24 months from March —May. Sexual maturity is attained at a carapace length of about 18 mm; maximum size is 45 mm. Most animals die after about 2.5 years; however, some live for three years. Molting activity ceases in winter. Cambarus tenebrosus young hatch in July and August. Most hatchlings remain in the burrows until October and November at which time they emerge in response to dominance behavior. Growth occurs throughout the winter months, and sexual maturity is attained in 20 – 22 months when the crayfish are about 40 mm in carapace length. Mature females oviposit during June and July after about 22–23 months, and probably again after 34–35 months. Mating occurs during the winter and spring. In Doe Run, maximum size attained is 65 mm carapace length. Cambarus tenebrosus probably lives for 36 – 38 months.     

Gonad characterization and reproductive seasonality in Siphonaria lessonii (Gastropoda: Heterobranchia) from the southwestern Atlantic Ocean

Histological characterization of the hermaphroditic gonad (HG) and seasonality of gametogenesis were investigated in a population of Siphonaria lessonii from the coast of Buenos Aires Province (37°16′S, 56°58′W). Monthly analysis of the frequency of gametogenic stages, as well as the number and mean size of oocytes, were used to determine reproductive events over a 2‐year period (June 2012–May 2014). Female and male gametes were observed simultaneously within acini of adult individuals and continuously throughout the period studied. Oogenesis commenced in the beginning of austral autumn, with gonads characterized mainly by proliferation of female cells. From this moment, oocytes gradually increased in number and area until spring, when a large number of individuals were found in the evacuation stage. The same trend was observed from early gonad maturation to advanced stages, indicating that gonad development was closely related to the frequency of oocyte stages and to the area (size) of oocytes. Spermatogenesis was also observed as a continuous process throughout the year, although spent acini were more frequent from November until February. Reproductive seasonality and gametogenesis were associated with changes in temperature and day length.     

Population Biology and Breeding Period of the Sand-Bubbler Crab <Emphasis Type="Italic">Dotilla Fenestrata</Emphasis> (Brachyura: Ocypodidae) from Southern Mozambique

The sand-bubbler crab Dotilla fenestrata (Hilgendorf, 1869) is the most common and abundant brachyuran in the intertidal area of many East African sandy shores. Monthly sampling surveys were performed from March 2001 to February 2002 at Praia do Triunfo, Southern Mozambique. At each sampling survey, 15 stations (0.25 m²) were sampled to a depth sediment of 30 cm. Crabs were identified, sexed, and measured for carapace width (mm). A total of 2456 crabs were collected of which 1247 were males (mean ± sd: 5.36 ± 0.04 mm), 938 non-ovigerous females (5.03 ± 0.03 mm) and 271 ovigerous females (5.15 ± 0.06 mm). The overall size frequency distribution showed a unimodal pattern suggesting a stable population with continuous recruitment. A clear sexual dimorphism was observed, with males being larger than ovigerous females, which in turn, were larger than non-ovigerous females. The overall sex ratio did not differ from 1:1. The annual reproductive cycle of Dotilla fenestrata was continuous and ovigerous females were recorded throughout the year, with peaks of occurrence during the warmer months (February–August). Despite of this continuous cycle, few juveniles were observed during the study period. These observations and the maximum size attained by adults supports the hypothesis that for this burrowing crab, recruitment may occur in different habitat than that occupied by adults. However, the studied area is favourable for growth, since the analysed population attains sexual maturity in smaller sizes than that from close areas.     

Seasonal prevalence of the Culex pipiens group (Diptera: Culicidae) larvae occurring in a puddle in the basement of an apartment building

The seasonal prevalence of the Culex pipiens group larvae occurring in a puddle in the basement of an apartment building was investigated from June 1993 to May 1994 (Period I), and from June 1994 to May 1995 (Period II). Totals of 25 237 individuals in Period I and 4989 individuals in Period II were collected: they were all C. pipiens group larvae, most of which were C. pipiens molestus. In Period I, the larvae occurred at a relatively low density in the hot months July and August; density began to increase from the cooler late September, peaked in late November, and was maintained at a high level until the third week of December. In Period II, in which mean air temperature was 5°C higher as of July and August than in Period I, larvae sharply decreased in number by one‐fifth of the total volume in Period I, and showed a peak density in the third week of July, and the peak continued until mid‐December. In Period I, the low temperature was favorable for oviposition activity of C. pipiens molestus, and accounts for the higher density of larvae in Period I than in Period II. C. pipiens molestus mostly stopped laying eggs between early December and late January. Larvae were not collected in March and April 1994 and in April 1995. However, considering that adult mosquitoes had been collected throughout the two periods except in March 1994, adults of C. pipiens molestus are thought to appear throughout the year.     

Seed survival and periodicity of seedling emergence in some species of Atriplex, Chenopodium, Polygonum and Rumex

Seeds or fruits of 10 weed species were collected in each of 3 years and mixed with the top 7·5 cm of sterilised soil which was confined in cylinders sunk in the ground outdoors and cultivated three times yearly. The numbers of seedlings emerging were recorded for 5 yr and the numbers of viable seeds remaining then determined. Few, if any, seedlings of Atriplex, Chenopodium or Polygonum spp. emerged in the autumn of sowing; the main emergence was consistently in March–May (A. hastata, A. patula), April–May (P. lapathifolium, P. persicaria), April–June (C. polyspermum), May–June (C. rubrum) or June–August (C. hybridum). When sown before November, some seedlings of Rumex crispus, R. obtusifolius and R. sanguineus appeared immediately. Most emerged in April in subsequent years. Seedling emergence was usually greatest in the first year; thereafter, with all species, seedling numbers decreased approximately exponentially from year to year. The mean numbers of seeds found to be viable after 5 yr ranged from 2·5% (R. sanguineus) to 16·6% (C. rubrum) of those sown.     

Population dynamics and population structure ofFerrissia wautieri (Mirolli, 1960) (Gastropoda,Ancylidae) in a pond near Nijmegen (The Netherlands)

Ferrissia wautieri, a freshwater limpet, is a widely distributed species in The Netherlands. In a pond near Nijmegen samples were taken twice a month over the year to study the population size and structure of this species in relation to the water temperature. Only ancyloids were found. Production of juveniles is temperature-dependent; peak numbers occurred in July and August. Just-hatched juveniles (shell length 0.6–1.0 mm) occurred over a lengthy period in the year, but were absent in March and April. During these months the collected numbers of specimens were very low. The largest specimens were collected during March, April and May.     

Population size structure,growth, arm number and damage in the sea star Archaster angulatus Müller and Troschel, 1842 (Echinodermata: Asteroidea)

Monthly sampling for the sea star Archaster angulatus revealed at least four cohorts with linear growth in the 0+ and 1+ year groups to about 26 months after which growth slows and conforms to the von Bertalanffy model of growth. The appearance of small individuals (arm radius (R) < 20 mm) from March to May is consistent with the discrete December/January spawning period. Sea stars attain R of 38.7 mm at one year, 73.7 mm at two years and maturity occurs in the second year. The 3+ year and 4+ year cohorts were difficult to detect reliably, but sample number peaks at 90–94 mm and 105–107 mm in January of both 2010 and 2011 are indicative of size at three and four years. Two methods of estimating von Bertalanffy growth parameters both yielded estimates of 127 mm for L_inf and k values of 0.41 and 0.49. Comparison of size at age estimates from growth models and cohort analysis suggested the actual value of k after maturity lies between 0.35 and 0.45. Four-armed (1.48%), six-armed (1.26%) and seven-armed (0.11%) individuals were present in the population and arm damage, thought to have resulted from sublethal predation was observed in 13.8% of sea stars.     

Differences in photoperiod‐induced diapause plasticity among different populations of the bark beetle Ips typographus and its predator Thanasimus formicarius

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