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.     

高原鼠兔(Ochotona curzoniae)冬季自然死亡率

以耳标观察法。1985年4-7月共捕标了样地内高原鼠兔(Ochotona curzoniae)幼鼠114只。到入冬前,死亡率为50.88%。第2胎出生的鼠死亡率明显地高于第1胎的死亡率。冬季死亡率呈现波动,入冬及开春时死亡率较高。鼠兔种群进入繁殖前期死亡率趋于零。初春样区存活标志鼠6只,经夏秋冬3季总计死亡率达94.74%。如按入冬时实有标志鼠计算,冬季死亡率为91.04%。     

Mortality pattern and age structure in two carabid populations with different seasonal life cycles

1. Adult populations of two carabid species, a spring breeder, Carabus yaconinus, and an autumn breeder, Leptocarabus kumagaii, were studied in a lowland habitat (area: 16,500 m²) by pitfall sampling and mark-recapture method. The seasonal change in population number, age structure and mortality pattern were clarified and related to their seasonal life cycles.
2. The survival rate of new adults from emergence to the first reproductive season was on the average 48% in C. yaconinus and 55% in L. kumagaii. In C. yaconinus, beetles which emerged later in the season survived more to the first reproductive season than those emerged earlier. C. yaconinus which had survived the pre-reproductive period mostly died out during the first reproductive season of 5 months, and about 8% survived until the second season. In L. kumagaii which had a short reproductive period in autumn, about 20% survived to the second reproductive season, and a small proportion even to the third reproductive season. Accordingly, the proportion of old beetles in the reproductive population was higher in L. kumagaii than in C. yaconinus.
3. The reproductive population of C. yaconinus contained on the average 1600 beetles and produced 3300 new adults. the L. kumagaii population contained on the average about 530 reproductives in autumn, and about 820 beetles emerged in the following year. The recruitment rate of new adults of C. yaconinus was higher than that of L. kumagaii, and this resulted in its higher population density. In L. kumagaii, however, the high adult survivorship and iteroparous reproduction were important for its population growth.
4. Relationship between seasonal adaptation and demographic strategies in the carabid populations were discussed.

     

Consequences of adult size for survival and reproductive performance in a herbivorous ladybird beetle

Abstract.

• 1 A univoltine herbivorous ladybird beetle Epilachna niponica (Coleoptera: Coccinellidae) shows a large variation in adult size within a population.
• 2 Large adults had higher survival from emergence to the reproductive season, and the size-dependent adult survival was most apparent during hibernation. On the other hand, adult survival during pre-hibernation contributed little to size-dependent overall survival.
• 3 Neither reproductive lifespan nor lifetime fecundity were a function of adult size, though large females produced larger size of egg batches.
• 4 Size of adult beetles was significantly reduced by leaf damage to plants on which they grew up on larval stage. Since leaf herbivory increases through the season, late emerged adults that were subjected to food deterioration during the larval period were smaller than early-emerged individuals.

     

Seasonal changes in the reproductive and life-history traits of Chrysomela populi L. (Coleoptera: Chrysomelidae)

Seasonal changes in the reproductive and life‐history traits of Chrysomela populi L. were investigated in Shobara (34°52′N, 133°01′E), Japan, in 2004 and 2005. Larvae were hatched and reared under natural photoperiod and temperature in 8 different periods between late April and early September in 2004. The incidence of adult diapause increased with progression of the season in 2004. The critical timing of diapause induction, as defined by 50% of females entering diapause, was estimated to occur between late July and early August. No effects of season on the survival rate from hatching to adult emergence, percentage ovipositing females and percentage females that deposited viable eggs were clearly detected. Adult weight at emergence fluctuated seasonally, which was probably caused by air temperature. No effect of season on the oviposition period was observed among females that averted diapause. Females that entered diapause in 2004 started oviposition from the first day of May in 2005. Reproductive output was significantly greater in diapause females than in non‐diapause females. This increase in the reproductive output of diapause females was caused by elongation of the oviposition period and consequently by enlargement of the number of egg clutches deposited. These results suggest that the seasonal timing of diapause induction in females of C. populi would be affected by various risks and benefits to reproduction and survival.     

Demography of a mediterranean microtine: the Mediterranean pine vole,Microtus duodecimcostatus

Microtus duodecimcostatus in a mediterranean vole which is not known to display spectacular increases in population numbers as in some microtine species. A population was studied in southern France with a capture-recapture method. The population included resident adults which have a high and constant survival rate (monthly estimate: 0.879), erratic adults (those caught once only), and juveniles which have a lower and constant survival rate. The adult survival rate was not sexbiased but the juvenile survival rate was higher in males (monthly estimates: 0.710 and 0.596 for males and females, respectively). Adult body weight did not vary seasonally. Residents had a higher mean body weight than erratics. Reproduction occurred all the year round. The proportion of reproductive females was higher among residents than among erratics. Population numbers varied seasonally. Our study points out thatM. duodecimcostatus is very different from microtine species which display cyclic fluctuations. Population studies on the subgenusPitymys (which containsM. duodecimcostatus and its closest related species) suggest that they are typically non-cyclic. The importance of social factors in the control of reproduction and maturation was evidenced inM. pinetorum. The role of such factors in the population regulation ofM. duodecimcostatus is discussed.     

Population structure and emergence order in the fruit-bat (Rousettus aegyptiacus: Mammalia, Chiroptera)

Population size and emergence order of R. aegyptiacus were studied in the Abas cave. Haifa, Israel. Throughout the reproductive period adult females populated the cave and the adult population consisted mainly of adult females except during winter when higher numbers of adult males were recorded. The proportion of juveniles increased consistently from spring to winter. Thus, it is suggested that the Abas cave serves as a maternity roost. Adult females in the reproductive state emerged from the cave earlier that juveniles and adult males. Social factors and differences in nutritional demands which may correspond to this different emergence order are discussed.     

Influence of adult and egg predation on reproductive success of Epirrita autumnata (Lepidoptera: Geometridae)

We studied the effects of predation and oviposition activity on reproductive success of a late-season moth, Epirrita autumnata by exposing adult females and eggs to predation in their natural habitat in two successive years. Daily survival rates of adult females ranged from 0.4 to 0.8, average being 0.7. Most predation occurred during nights and was caused by harvestmen and other invertebrate predators. Avian predation did not have an effect on adult survival rates, most likely because of the lateness of E. autumnata flight season. Eggs were also preyed upon by invertebrate predators, although a notable proportion of egg mortality was attributable to causes other than predation. Daily survival rates of eggs were more than 0.99. Using modeling based on empirical data on eclosion of female adults, their oviposition behavior and survival rates of adults and eggs, the daily survival rates were translated into population level consequences. Adult predation was estimated to decrease reproductive success of non-outbreaking E. autumnata by 60–85 percent and egg mortality by 20–40 percent. Predation on adult lepidopterans is a mortality factor potentially as relevant as predation in any other life history stage and thus, should not be ignored in studies of population regulation.     

Sexual dimorphism and intraspecific aggression,and their relationship to sex ratios in Caprella gorgonia Laubitz & Lewbel (Crustacea: Amphipoda: Caprellidae)

The amphipod Caprella gorgonia Laubitz & Lewbel is an obligate commensal on gorgonian octocorals. Its primary host is Lophogorgia chilensis (Verrill), found below 20 m.C. gorgonia breeds throughout the year, with wide fluctuations in abundance. Mating and oviposition follow molting. Sex reversal does not occur; two distinct sexes are present from the first instar after emergence from the brood pouch.Young males and females grow at approximately the same rate, but males are larger by a relatively constant increment. Males continue to grow at their original rate to a maximum size (about twice that of females). The growth rate of females is not limited by the onset of reproduction and brooding, but rather by an approach to maximum size when the rate is greatly reduced. Fecundity of females is not affected by size.The population sex ratio is about 1:3 (males:females), and about 1:4 among adults. The secondary sex ratio is 1:1. The post-emergence sex ratio bias is a result of heavier mortality among males. Sex ratios drop from 50% at emergence to 25% as females approach maximum size, then rise to 100% in larger size classes.Differential predation on males did not appear to be a source of any sex ratio bias. Adult males possess a “poison spine”, a puncturing weapon on the large second gnathopod, which functions in mating-related intraspecific combat with other males. Intraspecific male aggression during mating is a major cause of sex ratio bias. In the laboratory, increased density in breeding groups may affect mortality due to male aggression. In nature, adult sex ratios are negatively correlated with population density. The reproductive capacity of the population is not limited by a shortage of adult males, despite the low adult sex ratio.     

Life table analysis of the green rice leafhopper,Nephotettix virescens (distant) (Hemiptera: Cicadellidae), and efficient vector of rice tungro disease in asynchronous rice fields in Indonesia

Population dynamics of Nephotettix virescens was studied in 17 paddy fields transplanted at intervals of about 1 month in 1988–1990. The adult density was highest either in the immigrant or the 1st generation and sharply decreased to the 2nd generation. The survival rate of the 1st generation was lowest in the transition season when areal population density increased. Key factor analysis revealed that the nymphal and adult mortality of the 1st generation (kn) was the principal source of population fluctuations. No significant correaltion was found between kn and natural enemy density, natural enemy density/healthy egg density, or the precipitation during the nymphal period. On these bases adult emigration was suspected to be the key factor. Areal population build-up of N. virescens in the transition season was considered to occur as a result of increasing immigration to young stages of rice.     

The use of periodic matrices to model the population dynamics of the long-lived semelparous <Emphasis Type="Italic">Furcraea parmentieri</Emphasis> (Asparagaceae) in a temperate forest in central Mexico

Furcraea parmentieri (Roezl ex Ortgies) García-Mend. is a long-lived, semelparous threatened species with a restricted geographic distribution. We studied the demography of this species in southwest of Mexico City using periodic matrices. We followed the fate of 404 individuals (in 2006–2007) and performed seed germination and seedling establishment experiments in the field (in 2007–2008) to estimate survival, growth and reproduction probabilities of individuals in eight size categories, according to plant height. Population structure was characterized by a high number of saplings, as well as medium and large plants. We built three annual matrices that described the demography in different phases of the population cycle: regular years (RG) characterized by low fecundity and low adult mortality; mast-seeding years (MS) with low seedling emergence and high adult mortality (related to semelparity); and post mast-seeding years (PS) with a high emergence of seedlings and bulbils. Periodic matrices were built simulating three scenarios, which consisted of mast-seeding events occurring every 5, 10, or 15 years. Finite population growth rates (λ) were 1.03 (RG year), 0.99 (MS year), and 1.25 (PS year). The long term population growth rate values projected over a 90 year period (estimated on an annual basis) were higher as the frequency of mast-seeding events increased. We estimated that individuals reproduce at an age of 60–90 years and that most new recruits originate via sexual reproduction. Although the population has a potential for growth, its persistence may be threatened due to land use change.     

Poor horse traders: large mammals trade survival for reproduction during the process of feralization

We investigated density dependence on the demographic parameters of a population of Camargue horses (Equus caballus), individually monitored and unmanaged for eight years. We also analysed the contributions of individual demographic parameters to changes in the population growth rates. The decrease in resources caused a loss of body condition. Adult male survival was not affected, but the survival of foals and adult females decreased with increasing density. Prime-aged females maintained high reproductive performance at high density, and their survival decreased. The higher survival of adult males compared with females at high density presumably results from higher investment in reproduction by mares. The high fecundity in prime-aged females, even when at high density, may result from artificial selection for high reproductive performance, which is known to have occurred in all the major domestic ungulates. Other studies suggest that feral ungulates including cattle and sheep, as these horses, respond differently from wild ungulates to increases in density, by trading adult survival for reproduction. As a consequence, populations of feral animals should oscillate more strongly than their wild counterparts, since they should be both more invasive (as they breed faster), and more sensitive to harsh environmental conditions (as the population growth rate of long-lived species is consistently more sensitive to a given proportional change in adult survival than to the same change in any other vital rate). If this principle proves to be general, it has important implications for management of populations of feral ungulates.     

Population and Harvest Dynamics of Midcontinent Sandhill Cranes

Sandhill cranes (Antigone canadensis) inhabiting the midcontinent of North America have been hunted since the 1960s under management goals of maintaining abundance, retaining geographic distribution, and maximizing sustainable harvest. Some biologists have raised concerns regarding harvest sustainability because sandhill cranes have lower reproductive rates than other game birds. We summarized demographic information in an age-structured matrix model to better understand population dynamics and harvest. Population indices and recovered harvest since the early 1980s suggest midcontinent sandhill cranes have experienced an average long-term annual growth of 0.9%; meanwhile, harvest has increased 1.8% annually. Adult survival and recruitment rates estimated from field data required modest adjustments (1–3%) so that model-derived growth rates matched growth estimated from a long-term survey (0.887 adult survival and 0.199 females/breeding female). Considering 0.9% long-term annual growth, sandhill cranes could be harvested at a rate of 6.6% if harvest was additive to natural mortality (assumed to be 0.05) or 11.3% if harvest mortality compensated for natural mortality. Life-history characteristics for long-lived organisms and demographic evidence suggested that hunter harvest was primarily additive. Differential harvest rates of segments of sandhill cranes in the midcontinent population derived from differential exposure to hunting suggested potentially unsustainable harvest for greater sandhill cranes (A. c. tabida) from 2 breeding segments. Overall, demographic evidence suggests that the harvest of sandhill cranes in the midcontinent population has been managed sustainably. Monitoring activities that reduce nuisance variation and estimate vital and harvest rates by subspecies would support continued management of sandhill cranes that are of interest to hunters and bird watchers. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.     

Changes in body mass and feeding behaviour in male harbour seals, Phoca vitulina, in relation to female reproductive status

Loss of body mass has been used as an index of the cost of reproductive effort in mammals. We studied changes in body mass of male harbour seals, Phoca vitulina , during the breeding season on Sable Island, Nova Scotia, Canada. Individually marked subadult ( n = 21) and adult ( n = 22) males were captured at approximately six-day intervals throughout the breeding season. Adult males weighed an average of 108 kg ± 5·6 (S.E.) at initial capture, whereas subadults weighed an average of 76 ± 6·6 kg. The rate of mass loss by adult males did not differ from zero during the pre-mating period (i.e. the period without receptive females), but differed significantly from zero (-0·91 ± 0·007 kg/day) during the mating period (i.e. the period with receptive females). By contrast, the rate of mass change of subadults did not differ from zero in either period, indicating that food availability was unlikely to be responsible for the observed changes in adults. Adult males lost up to 24% of body mass during the breeding season. Examination of sera for the presence of chylomicrons (i.e. evidence of recent feeding) also suggested that adults stopped feeding during the mating period, while subadults did not. These results suggest that reproduction represents a significant energetic cost to adult male harbour seals.     

Effect of soil burial depth and wetting on mortality of diapausing larvae and patterns of post-diapause adult emergence of sorghum midge, Stenodiplosis sorghicola (Coquillett) (Diptera: Cecidomyiidae)

Abstract  In south-eastern Queensland, Australia, sorghum planted in early spring usually escapes sorghum midge, Stenodiplosis sorghicola , attack. Experiments were conducted to better understand the role of winter diapause in the population dynamics of this pest. Emergence patterns of adult midge from diapausing larvae on the soil surface and at various depths were investigated during spring to autumn of 1987/88–1989/90. From 1987/88 to 1989/90, 89%, 65% and 98% of adult emergence, respectively, occurred during November and December. Adult emergence from larvae diapausing on the soil surface was severely reduced due to high mortality attributed to surface soil temperatures in excess of 40°C, with much of this mortality occurring between mid-September and mid-October. Emergence of adults from the soil surface was considerably delayed in the 1988/89 season compared with larvae buried at 5 or 10 cm which had similar emergence patterns for all three seasons. In 1989/90, when a 1-cm-deep treatment was included, there was a 392% increase in adult emergence from this treatment compared with deeper treatments. Some diapausing larvae on the surface did not emerge at the end of summer in only 1 year (1989/90), when 28.0% of the larvae on the surface remained in diapause, whereas only 0.8% of the buried larvae remained in diapause. We conclude that the pattern of emergence explains why spring plantings of sorghum in south-eastern Queensland usually escape sorghum midge attack.     

Population Ecology of the Riparian Frog Eleutherodactylus cuneatus in Cuba

A population of the poorly known riparian frog Eleutherodactylus cuneatus was studied for 1 yr along a mountain stream in eastern Cuba. We examined population structure, seasonal and daily activity, growth, and habitat use using mark-recapture and call-point counts. Juveniles were observed during all survey periods with a spike in March. Higher numbers of adults were present in May–July, associated with longer day length, warmer temperatures, and the onset of the rainy season. This was coincident with higher calling activity away from the stream, suggesting an increase in both reproductive and nonreproductive activity in the warmer months between May and September. The number of individuals peaked at 2000–2200 h, but high numbers of individuals were visible throughout the night. Lower activity levels were observed throughout the day. Population size estimates were 84–131 adults and 124–304 juveniles, with averages of 110 and 236 individuals, survival rates were high but capture probabilities were low for a 5-d period in March 2004. Growth rate was negatively related to the size of recaptured individuals, although decreases in growth rate were slight. Frogs were found either in the water (49.7%), or in the banks and on the ground adjacent to the stream where most individuals were found on the ground under the cover of rocks, leaf litter, or large palm fronds. These results provide baseline knowledge of E. cuneatus population dynamics and ecology needed for a rapid detection of any decline this population may undergo in the future.     

Demography of the Heike firefly Luciola lateralis (Coleoptera: Lampyridae), a representative species of Japan’s traditional agricultural landscape

Populations of the Heike firefly, Luciola lateralis, a representative species of Japan’s traditional agricultural landscape (known as satoyama), have recently experienced rapid declines in many areas of Japan. Owing to the popularity of this firefly, many local communities have increased conservation efforts through the restoration of aquatic habitat complexes in satoyama. To provide fundamental parameters to predict population dynamics of the firefly, we conducted a mark–recapture study in restored paddy fields, and we estimated adult population parameters such as population size, survival, recruitment, sex ratio, and body size. We found that capture probability generally decreased as the season advanced, probably because of seasonal changes in detectability and/or firefly behavior. The daily survival rate of adults decreased over the season and may be related to a seasonal decline in adult body size. Adult population exhibited a highly male-biased sex ratio. Firefly abundance in the restored paddy fields doubled during the 4-year study period. Our analysis showed that adult detectability, recruitment, and survival rate are seasonally variable and could affect population size estimates obtained by a simple flash census. The mark–recapture technique can provide precise estimates of adult L. lateralis population characteristics and, thus, is a valuable method for predicting firefly populations and assessing the success of the restoration program.     

Survival,site fidelity,and the population dynamics of Piping Plovers in Saskatchewan

ABSTRACT To conserve threatened species, managers require predictions about the effects of natural and anthropogenic factors on population growth that in turn require accurate estimates of survival, birth, and dispersal rates, and their correlation with natural and anthropogenic factors. For Piping Plovers (Charadrius melodus), fledging rate is often more amenable to management than adult survival, and population models can be used to estimate the productivity (young produced per breeding female) necessary to maintain or increase populations for given levels of survival. We estimated true survival and site fidelity of adult and subadult (from fledging to second year) Piping Plovers breeding in Saskatchewan using mark‐resight data from 2002 to 2009. By estimating true survival rather than apparent survival (which is confounded with permanent emigration), we were able to provide more accurate projections of population trends. Average adult and subadult survival rates during our study were 0.80 and 0.57, respectively. Adult survival declined over time, possibly due in part to the loss of one breeding site to flooding. Average adult and subadult site fidelity were 0.86 and 0.46, respectively. Adult site fidelity declined during our study at two study sites, most strongly at the flooded site. Male and female Piping Plovers had similar survival rates, but males had greater site fidelity than females in some years. Based on our survival estimates, productivity needed for a stationary population was 0.75, a benchmark used for plover management on the Atlantic Coast, but not previously estimated for Prairie Canada. In stochastic simulations incorporating literature‐based variation in survival rates, productivity needed for a stationary population increased to 0.86, still lower than that previously estimated for western populations. Mean productivity for our study sites ranged from 0.87 to 0.96 fledged young per pair. Our results suggest that fledging rates of Piping Plovers in Saskatchewan were sufficient to ensure a stationary or increasing population during our study period. However, large‐scale habitat changes such as drought or anthropogenic flooding may lead to dispersal of breeding adults and possibly mortality that will increase the fledging rate needed for a stationary population.     

Columbian sharp-tailed grouse female and nest survival in northwestern Colorado

Wildlife management and conservation can be challenging when the demography of a focal species is unknown or limited given that fecundity and adult survival influence population growth. The Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) have been reduced to ≤10% of their former range since the early 1900s. We conducted a 3-year study (2015–2017) across 4 study sites in northwestern Colorado, USA, to evaluate female hazard and nest survival. We trapped and marked 270 female sharp-tailed grouse and identified 275 nests for our hazard and survival analyses. Females during the breeding stage of the reproductive season experienced more hazard compared to the nesting and the early and late post-nesting stages for females without broods. Females experienced a higher degree of hazard during the breeding stage and mortality risk was >3 times higher than the nesting stage, >7 times higher than early post-nesting (EPN)-no brood stage, and >5 times higher than the late post-nesting (LPN)-unsuccessful stage. Two reproductive season stages (LPN-successful and EPN-brood) provided marginal inference. Nest incubation initiation date and nest age best described nest daily survival. Females that initiated incubation of initial nests earlier in the season experienced lower nest daily survival than later in the incubation season. Because female Columbian sharp-tailed grouse hazard varied among different reproductive season stages, we recommend that wildlife managers develop management actions that reduce hazard during the specific reproductive season stages (i.e., the breeding season). For Columbian sharp-tailed grouse in Colorado, we recommend that Colorado Parks and Wildlife collaborate with federal farm program agencies to implement a no-tillage restriction from 1 May through 30 June for active agricultural fields within 2 km of active Columbian sharp-tailed grouse leks to enhance nest survival.     

Dynamics of Pneumonia in a Bighorn Sheep Metapopulation

Abstract: We investigated the dynamics of 8 populations of a bighorn sheep (Ovis canadensis) metapopulation in Hells Canyon, USA from 1997 to 2003. Pneumonia was the most common cause (43%) of adult mortality and the primary factor limiting population growth. Cougar (Puma concolor) predation was the second most-frequent source (27%) of adult mortality but did not reduce the rate of population growth significantly. Most pneumonia-caused mortality occurred in fall and early winter and most cougar predation occurred in late winter and early spring. Average annual survival of adult males (0.84) was lower than females (0.91). Pneumonia was the most common known cause of lamb mortality (86%), and pneumonia-related mortality was detected whenever summer lamb survival was <50%. Pneumonia-caused mortality rates in lambs were high from 21 days to 91 days of age and peaked at 42 days to 70 days. Summer pneumonia epizootics in lambs were independent of pneumonia-caused mortality in adults. Pneumonia-caused mortality occurred at the population level and was not synchronized geographically or temporally among populations. Although catastrophic all-age pneumonia-epizootics have previously been described in bighorn sheep, we found that chronic, although sporadic, pneumonia-caused mortality in adults and lambs can also have important effects on the dynamics of bighorn sheep populations.