Anatomical and histological changes during dormancy in twococcinellidae

The gonads of both females and males ofSemiadalia undecimnotata Schneid, were studied during the estivo-hibernation period (August–May). The ovaries remain unripe in diapausing females, the ovarioles being formed by mere germaria until late April (or early May) when the previtellogenesis begins. In some years, the stage of the first oocyte is attained in females staying still in the hibernation quarters. On the contrary, both the spermatogenesis and spermateliosis proceed in the testes of diapausing males so long as the ambiant temperature is sufficiently high (August–September, April–May). Only in the coldest period of dormancy (November–March) the tissue of testicular follicles ceases to be active. Since mid-April the spermatogenesis and spermateliosis are resumed completely and the males fertilize the females, as is shown by dissections of their spermathecae. Seminal vesicles are always full of sperms. The digestive tract is empty in inactive coccinellids and the size of the fat body gradually diminishes in the course of estivo-hibernation.

The dependence of the activity of the tissue of testicular follicles on the ambient temperature was proved experimentally in bothS. undecimnotata andCoccinella septempunctata L. The temperature of +12°C enables a natural regression, while an abrupt transfer to +5°C renders gradual emptying of follicles impossible.

     

Annual changes in testicular development and plasma sex steroids in the captive male dojo loach <Emphasis Type="Italic">Misgurnus anguillicaudatus</Emphasis>

Testicular development in the captive male dojo loach Misgurnus anguillicaudatus was examined monthly in relation to the levels of plasma sex steroids [testosterone (T), 11-ketotestostrone (11-KT), and 17,20β-dihydroxy-4-pregnen-3-one (DHP)]. On the basis of testicular histology, the annual gonadal cycle was found to be divisible into 3 periods: the recovery and proliferation period, which mainly consists of early spermatogenic testis from August to November (reproductive phase I); the preparation period for the next spawning period, which mainly consists of late spermatogenic testis from December to April (reproductive phase II); and the mature period, characterized by a high proportion of mature testis from May to July (reproductive phase III). Individual variability in testicular development was high, and continuous spermatogenesis was observed throughout the year. High levels of plasma T, 11-KT, and DHP were observed during reproductive phase III. 11-KT began to increase in February, while T was present at low levels in reproductive phase II. These results suggest that the physiologically active season of testis development for breeding in the dojo loach is from May to July, although spermatogenesis occurs throughout the year.     

Time and size at seaward migration influence the sea survival of Salmo salar

Whether time of seaward migration of young Atlantic salmon Salmo salar influences their subsequent survival and growth was investigated in the River Imsa, south‐western Norway. Salmo salar were tagged when moving downstream through a trap near the outlet between 1976 and 2010 and recaptured on their adult return. Most descended as smolts in April and May, but some descended during the other months of the year. Annual variation in timing of the smolt migration was significantly correlated with variation in water temperature during spring. Mean total body length of the descending S. salar varied with month of seaward migration. The sea survival of S. salar emigrating from the River Imsa between January and May was 2·8 times higher than for those descending between June and December. The sea survival of the various cohorts decreased with increasing river temperature in April to May, prior to the smolt migration, and decreasing day number when the smolts moved to sea. The size of smolts descending the river between April and May did not affect the survival at sea as much as it affected the survival of migrants descending in any other month of the year. The majority of the downstream migrating S. salar were 2 years old, but proportionally, more 1 year olds moved downstream in the autumn than in the rest of the year. Mean duration between downstream migration of the young and the return migration of the grilse was shortest (12·7 months) for those descending in July and August and longest for those descending in October (21 months). Mean monthly specific growth rate was highest for those migrating downstream between May and July and lowest for those emigrating in September. Based on the present results, it was hypothesized that S. salar emigrating between April and August migrated directly out into the ocean, while those that emigrated between October and March stayed in the estuary until the subsequent spring.     

Evoluzione Della Cerchia Legnosa in Quercus Aegilops L. a Tricase

Abstract

The author has examined the cambial activity and the formation of the annual ring in Quercus aegilops from February 1954 to February 1955. Material was collected at Tricase (Lecce) the only Italian locality where this oriental species grows although it is doubtful whether it is spontaneous.

Cambial activity starts in the middle of April both in the main stem and in the branches following flowering and bud development. It goes on for about five months until the second half of August forming a complete growth ring. This annual ring shows the normal sequence of early wood with wide vessels formed during the second half of April and the whole of May, intermediate wood with medium and small size vessels, parenchima, and fibres formed in June-July, and late wood with few small size vessels, parenchima, and fibres formed from the end of July to middle August.

There is no reawakening of cambial activity in autumn even if the climatic conditions are favourable. Tylosis are very easily formed in the wood vessels and by this process the plant can withstand the drought of the Apulian summer.     

Seasonal spermatogenic cycle and morphology of germ cells in the viviparous lizard Mabuya brachypoda (Squamata,Scincidae)

We describe seasonal variations of the histology of the seminiferous tubules and efferent ducts of the tropical, viviparous skink, Mabuya brachypoda, throughout the year. The specimens were collected monthly, in Nacajuca, Tabasco state, Mexico. The results revealed strong annual variations in testicular volume, stages of the germ cells, and diameter and height of the epithelia of seminiferous tubules and efferent ducts. Recrudescence was detected from November to December, when initial mitotic activity of spermatogonia in the seminiferous tubules were observed, coinciding with the decrease of temperature, photoperiod and rainy season. From January to February, early spermatogenesis continued and early primary and secondary spermatocytes were developing within the seminiferous epithelium. From March through April, numerous spermatids in metamorphosis were observed. Spermiogenesis was completed from May through July, which coincided with an increase in temperature, photoperiod, and rainfall. Regression occurred from August through September when testicular volume and spermatogenic activity decreased. During this time, the seminiferous epithelium decreased in thickness, and germ cell recruitment ceased, only Sertoli cells and spermatogonia were present in the epithelium. Throughout testicular regression spermatocytes and spermatids disappeared and the presence of cellular debris, and scattered spermatozoa were observed in the lumen. The regressed testes presented the total suspension of spermatogenesis. During October, the seminiferous tubules contained only spermatogonia and Sertoli cells, and the size of the lumen was reduced, giving the appearance that it was occluded. In concert with testis development, the efferent ducts were packed with spermatozoa from May through August. The epididymis was devoid of spermatozoa by September. M. brachypoda exhibited a prenuptial pattern, in which spermatogenesis preceded the mating season. The seasonal cycle variations of spermatogenesis in M. brachypoda are the result of a single extended spermiation event, which is characteristic of reptilian species. J. Morphol. © 2012 Wiley Periodicals, Inc.     

ENROL IN THE SOCIETY

Earlé, R. A. 1981. Factors governing avian breeding in Acacia savanna, Pietermaritzburg, Part 2: Intrinsic factors. Ostrich 52:74-83.

The most important factor governing avian breeding in Acacia savanna is the body condition (protein reserve) of the bird. Breeding can take place only if the female has a large enough protein reserve to form eggs. The protein reserve is dependent on an adequate food supply which is once again dependent on climatic factors. Both the protein reserve and body weight of several species were found to be at their lowest towards the end of the breeding season. Moult and breeding were found to be largely separated in time. In most species examined testis activity was at its lowest between April and June and highest from September to January. Colius striatus showed a less seasonal pattern of testis activity while Nectarinia talatala showed very early testis activity and had fully active testes in May.     

Population recovery of the sea urchin Lytechinus variegatus in a seagrass flat (Araruama Lagoon,Brazil): the role of recruitment in a disturbed environment

Summary

The size, structure, and density of a population of Lytechinus variegatus were recorded from a shallow seagrass bed (Halodule wrightii) at 40-day intervals from April 1994 to April 1995. A local mass mortality was observed in May 1994. The density declined from 0.57±0.10 to 0.06±0.05 ind.m^?2, mean size declined from 37.6±0.49 to 16.2±2.14 mm and maximum size from 75 to 40 mm. Ten months after mortality, the maximum and mean sizes had returned to initialvalues, but density had not (0.10±0.03 ind.m^?2). A second, smaller mass mortality occurred in April 1995. High values of gonad index were recorded before mortality (9.40±5.97) and after population recovery (11.96±5.74). Recruitment was continuous throughout the year, but reached a peak from August to October. This can he related to the patterns of upwelling in the region. Mass mortality is probably an annual event in this population that can be correlated with the occurrence of low tides during daytime in the fell. The population can recover during the summer when low tides occur during the night. The massive input of recruits prevents extinction of the population during the season of high mortality. Population recovery depends on the magnitude of recruitment.     

昆明红火蚁种群发生特征

【目的】2013年10月云南省元谋县首次发现红火蚁。掌握红火蚁蚁巢各品级发生动态,能为当地红火蚁的防控提供技术支撑。【方法】2015年1—12月,在昆明宜良县对红火蚁蚁巢取样、分离,红火蚁取样、称重,统计红火蚁各品级的头数。【结果】地上蚁巢红火蚁蚁群数量发生高峰期在8—9月,其次是3—4月。蚁后数量比例高峰在3—4月;有翅雌蚁比例高峰在4月,其次是7月;有翅雄蚁比例高峰的在5月,其次是9月;生殖蚁幼虫和蛹比例高峰的3、4和12月。地上蚁巢工蚁、兵蚁、职能蚁幼虫和蛹数量发生的高峰期在8—9月,发生小高峰期在4月。【结论】昆明红火蚁蚁群数量动态有2个峰值,第一个峰值为8—9月,以职能蚁防治为主;第二个蜂值3—4月,以生殖蚁和职能蚁防治为主。该结果为昆明红火蚁防控技术提供了数据支撑。     

Cyclical Changes in the Testis of the Hagfish Eptatretus burgeri (Cyclostomata)

The development of the spermatogenetic stages in the testis of the hagfish Eptatretus burgeri was studied by means of histological techniques. These animals have an annual reproductive cycle with a spawning season in October. Spermatocytes begin to appear in January and reach a maximum in March. The development of spermatids of stage I and stage II starts in April and June, respectively. In August about 35% of the testicular follicles contain spermatids of stage II. The gonadosomatic index shows a more or less constant increase from November until August. During the spawning season, no animals with well developed testis could be trapped. About 10% of male hagfish bear undeveloped gonads.     

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 dynamics,productivity and biomass allocation ofZizania latifolia in an aquatic-terrestrial ecotone

The population and production ecology of aZizania latifolia stand at a sheltered shore of the Hitachi-Tone River were investigated. Shoot emergence was observed twice a year; the fist was a synchronized shoot emergence in April and the second was from August to October. Aboveground biomass was mostly occupied by leaves and peaked at 1500 g dry weight m⁻² in August. The belowground biomass also reached its peak, 750 g dry weight m⁻², in August. The secondary shoots were small in spite of their high density. Leaves were produced continuously throughout the season. The leaf life span was as short as 55.6 days for cohorts that emerged from May through to September. Total annual net production ofZ. latifolia could be more than 3400 g dry weight m⁻². Shoot clusters of several centimeters were observed in April. The following self-thinning caused a regular distribution of the remaining shoots in August. Most shoots produced in August to October were found near a shoot persisting since April. They showed more concentrated distribution than shoots in April. A large biomass allocation to leaves and the ability to produce many clump shoots during the late growing period may facilitate dominance ofZ. latifolia in relatively sheltered sites.     

The role of refuge areas in the phenology of Rhopalosiphum padi in low rainfall cropping areas of South Australia

Extensive surveys of possible aphid habitats in South Australia indicated that irrigated perennial grass pastures in the Mount Lofty Ranges and Lower Murray Valley were summer refuges for Rhopalosiphum padi (L.) (Hemiptera: Aphididae). Large numbers of aphids build up in these pastures each year during autumn (April and May) with numbers peaking in May. The size of the May peak was related to the number of aphids surviving the summer. The proportions of alates were highest in May and August/September. Both peaks coincided with a photoperiod of between 11.2 and 11.5 h, and partial correlations suggested that aphid density, photoperiod and temperature were all significant determinants of alate production.     

On the migration of the Whimbrel,Numenius phaeopus,in Turkey

Abstract

The Whimbrel (Numenius phaeopus) is a scarce but regular passage visitor in Turkey. Spring migration has its peak in April, autumn migration in August/September (medians are April 23th and August 29th). Detailed information on flock size, wintering, main resting sites etc. is given and compared with other Middle East countries.     

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.     

Seasonal changes in taxon richness and abundance of mobile invertebrates inhabiting holdfast of annual kelp Ecklonia radicosa (Phaeophyceae,Lessoniaceae) at the central Pacific coast of Japan

To investigate seasonal changes in the taxon richness and abundance of mobile invertebrates inhabiting holdfasts of the warm temperate annual kelp Ecklonia radicosa, five holdfasts were collected monthly at the central Pacific coast of Japan from April to November 2014. During the study period, there was little variation in holdfast height and diameter, which ranged from 5.9 to 8.5 cm and from 7.1 to 10.8 cm, respectively. In total 7087 animals were collected from 40 holdfasts (177.2 individuals inds./holdfast, on average). The number of mobile invertebrates gradually increased from May (15 ± 9.9 inds./holdfast) to August (346 ± 152.5 inds./holdfast), with over 300 inds./holdfast until October before rapidly decreasing in November (110 ± 85.6 inds./holdfast). Similarly, taxon richness increased gradually from April (4.3 ± 1.0 taxa/holdfast) to August (11.0 ± 3.7 taxa/holdfast), and decreased in November (8.6 ± 2.3 taxa/holdfast). Interestingly, hundreds of mobile invertebrates inhabited holdfasts of kelp plants that had shed their blade in October and November. Taxon composition from August to October and the number of invertebrates from July to November were comparable to data previously reported for perennial kelps. In this study, the importance of annual Ecklonian species as biogenic habitats was demonstrated for the first time.     

Ecological studies on the community of drifting seaweeds in the south-eastern coastal waters of Izu Peninsula, central Japan. I: Seasonal changes of plants in species composition, appearance, number of species and size

Seasonal patterns of drifting seaweeds in the southeastern coastal waters of Izu Peninsula of central Japan were examined by sampling 966 patches from spring to autumn 1991–1993. In total, 57 plant species appeared, including 10 epiphytic algal species. Monthly totals of the number of species, excluding epiphytic aigae, were highest in May (33) and August (27), though 19–21 species of sargassaceous algae were found from May to August, The number of species, excluding epiphytic algae, in one patch of drifting seaweeds was 1 to 11 (x?= 2.93 ± 2.06) with high richness in May a result of almost entirely sargassaceous species. The wet weight of each patch and maximum stipe length of plants varied from 5 to 6970 g and from 20 to 840 cm (x?= 536.1 ± 782,3 g and 110.6 ± 76.8 cm), respectively, with highs in April and May. Out of 18 species common to all years, 10 species dominated the top or second rank in monthly pooled frequency of appearance. Seasonal changes of these 10 major species were examined, Sargassum horneri (Turner) C. Agardh and Hizikia fusiformis (Harvey) Okamura were abundant in April, but were replaced partly by Sargassum muticum (Yendo) Fensholt in May and largely by Sargassum yamamotoi Yoshida in June. In July, Sargassum nipponicum Yendo and Sargassum piluliferum (Turner) C. Agardh dominated. Subsequently, the major species shifted to Sargassum ringgoldianum Harvey and S. yamamotoi in August, Sargassum micracanthum (Kützing) Endlicher, Sargassum macrocarpum C. Agardh and Zostera marina Linnaeus in September, and S. ringgoldianum and S. micracanthum in October. However, the occurrence of S. yamamotoi, S. nipponicum and S. piluliferum in June or July were particularly heterogeneous compared with other areas of Japan. Dendrogram analysis was done based on frequency of appearance. Pooled monthly samples were divided into three groups characterized from the dominant species, degree of domination, weight, length and number of species of drifting seaweeds as well as the degree of diversity or evenness in appearance. This characterization indicated that the diversity and abundance of drifting seaweeds were higher from April to June than in later months.     

高寒草甸生态系统中高原鼠兔的繁殖特征

2002年4月至8月,在中国科学院海北高寒草甸生态系统定位站附近,采用标志重捕法对高原鼠免的繁殖特征进行了研究。高原鼠兔的繁殖具有明显的季节性差异,4月下旬和5月为繁殖高峰期,雄性的睾丸重而饱满,雌性的怀孕率最大。雄性成体的体重和睾丸重在繁殖期的不同时段具有显的差异,在4月11日至5月10日、6月11日至7月10日体重和睾丸重之间呈显正相关。雌性怀孕早期胚胎数与临产前胚胎数没有显差异,未发现胚胎吸收现象;同时,胚胎数在繁殖期的不同时段存在显差异。采用种群统计学中同生群的划分方法,将5～8月份出生的幼体依次记为L1、L2、L3、L4。在出生后20天内L1、L2幼体存活率明显高于L3、L4;在从出生50天至80天期间L4的存活率显高于L2。当年出生的雌雄幼体在发育上存在不同步现象,当年出生的雌性幼体性成熟早,有的可以直接参加繁殖,但当年出生的雄性幼体却无此现象。结果表明：在海北地区,经过综合治理后,高原鼠兔的生境发生改变,其繁殖策略也随之发生改变,即,减少每次繁殖活动的投入,增加繁殖次数,延长繁殖时间。     

Reproductive biology of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters

The reproductive activities of the silver pomfret, Pampus argenteus (Euphrasen), in Kuwait waters were investigated from March 1996 to February 1998. Observations on the seasonal distribution of maturity stages and variations in seasonal fluctuations in the gonadosomatic index (GSI) confirmed recent findings that the spawning period begins in May. The species has a prolonged spawning period in the females extending from May to August, whereas the males mature in April and ripe specimens were encountered in monthly samples until September. The recruitment pattern confirmed the one breeding season. There are two spawning peaks, the first in May and the second in August. Variations in GSI relative to fish length indicated that females and males are most fecund at about 24.5–26.4 cm and 20.5–22.4 cm length classes, respectively. The males mature earlier than females, at a minimum size of 12.5–14.4 cm, while the females mature at 20.5–22.4 cm. The oocyte diameter‐frequency distribution suggests a serial rhythm of spawning. Fecundity ranged from 28 965 to 455 661 and correlated positively with: (a) standard length (P < 0.006); (b) ovary weight (P < 0.001); and (c) body weight (P < 0.001), and negatively with egg size (P < 0.003).     

Reproductive biology of little tunny,Euthynnus alletteratus (Rafinesque), from the north‐eastern Mediterranean Sea

The study aimed at identifying spawning season and potential year classes reaching maturity in the north‐eastern Mediterranean, an area where little information on tuna spawning is available. Gonads (60 ovaries and 36 testis) were obtained from little tunny, Euthynnus alletteratus. The fish were caught between November 2002 and May 2005 in the north‐eastern Mediterranean Sea. The ovaries were histologically examined to determine the reproductive conditions and developmental stages of oocytes. Seven females sampled in May, July, and August were sexually mature (stage III or IV). The gonado‐somatic index (GSI) indicated that spawning generally occurred between May and September. The most intensive spawning period was observed between July and August. The sex ratio was calculated as 1 : 1.7 M/F (total n = 96). The length and weight relationship was calculated with W = 0.038 L^2.77, ages from year I to IV being included in the analysis.     

Time-course of programmed cell death during leaf senescence in <Emphasis Type="Italic">Eucommia ulmoides</Emphasis>

Leaves of Eucommia ulmoides Oliv. harvested between April to November were examined for programmed cell death (PCD) during growth and senescence. Leaves developed in April, becoming fully expanded in late May, remaining unchanged until November when they started to dehisce. Falling leaves retained a green color. Our results showed that (1) mesophyll cells gradually reduced their nuclei from September to November, (2) positive TUNEL signals appeared on the nuclei from August, (3) ladder-like DNA fragmentation occurred in September and October, and (4) a 20-kDa Ca²⁺-dependent DNase appeared in these same months. In fallen leaves, intact mesophyll cell nuclei could not be detected, but a few cells around the vascular bundle had nuclei. Therefore, (1) programmed cell death (PCD) of leaf cells occurred in the leaves of E. ulmoides, (2) the progress of mesophyll cell PCD lasted for more than 2 months, and (3) PCD of leaf cells was asynchronous in natural senescing leaves. Electronic Publication