Seasonal changes in the ovariuterus of female Scorpio maurus fuscus (Scorpiones; Scorpionidae), and the effect of higher temperature

Changes in the ovariuterus of Scorpio maurus fuscus during the period of one year, and under stressful thermal conditions, are described. The ovariuteri of most females in the population contained 1 generation of large, embryonic diverticulae (Ed) and variable numbers of small, bud-like rudimentary diverticulae (Rd) belonging to 3–5 generations. Most females contained 1 or 2 generations of degenerated (Dd), post-partum diverticulae, but some, probably virgins, lacked them. The latter females were significantly (P<0.05) smaller than the others. They also contained a significantly higher (P<0.0001) number of Rd than is usually found in the other females. Embryonic diverticulae (Ed) of females with 1 generation of Dd (Dd₁) were significantly longer (P<0.05) than Ed of females with 2 generations of Dd (Dd₁+Dd₂). The numbers and dimensions of the various diverticulae changed during the year. Under stressful thermal condition, the total number of Dd increased, and these were considerably longer than those observed under normal ambient conditions.     

A different oogenetic pattern in a US apoikogenous scorpion, Vaejovis spinigerus (Scorpiones, Vaejovidae)

The ovariuterus of the scorpion Vaejovis spinigerus (Scorpiones, Vaejovidae) differs from that of all other apoikogenic species studied so far in that the oocytes mature inside, rather than on the outer surface, of the ovariuterus tubes. Only the small, second and third oocyte generations are situated on the outer surface, sometimes even on top, of the mature oocytes. This oogenetic pattern has so far not been described in any other scorpion species. Since no males were found in the populations studied here, this species can be assumed to be parthenogenetic. However, this point needs more concrete proof.     

Histological and ultrastructural aspects of the nasal complex in the harbour porpoise,Phocoena phocoena

During the evolution of odontocetes, the nasal complex was modified into a complicated system of passages and diverticulae. It is generally accepted that these are essential structures for nasal sound production. However, the mechanism of sound generation and the functional significance of the epicranial nasal complex are not fully understood. We have studied the epicranial structures of harbor porpoises (Phocoena phocoena) using light and electron microscopy with special consideration of the nasal diverticulae, the phonic lips and dorsal bursae, the proposed center of nasal sound generation. The lining of the epicranial respiratory tract with associated diverticulae is consistently composed of a stratified squamous epithelium with incomplete keratinization and irregular pigmentation. It consists of a stratum basale and a stratum spinosum that transforms apically into a stratum externum. The epithelium of the phonic lips comprises 70–80 layers of extremely flattened cells, i.e., four times more layers than in the remaining epicranial air spaces. This alignment and the increased number of desmosomes surrounding each cell indicate a conspicuous rigid quality of the epithelium. The area surrounding the phonic lips and adjacent fat bodies exhibits a high density of mechanoreceptors, possibly perceiving pressure differentials and vibrations. Mechanoreceptors with few layers and with perineural capsules directly subepithelial of the phonic lips can be distinguished from larger, multi‐layered mechanoreceptors without perineural capsules in the periphery of the dorsal bursae. A blade‐like elastin body at the caudal wall of the epicranial respiratory tract may act as antagonist of the musculature that moves the blowhole ligament. Bursal cartilages exist in the developmental stages from fetus through juvenile and could not be verified in adults. These histological results support the hypothesis of nasal sound generation for the harbor porpoise and display specific adaptations of the echolocating system in this species. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.     

Formation of the diverticular lumen that enables oocyte fertilization in katoikogenic scorpions,Heterometrus spinifer and Opistophthalmus boehmi (Scorpionidae)

The structure of diverticula of the female gonads was analyzed in two scorpions from the family Scorpionidae by means of standard microscopic techniques (light microscopy, histochemistry, transmission electron microscopy). In scorpions, the female gonad, termed the ovariuterus, participates in two consecutive processes: oogenesis and embryogenesis. In sexually reproducing scorpions, the ovariuterus is also involved in fertilization. Both scorpions under study reproduce sexually. They also represent the katoikogenic type of development, which means that oogenesis, fertilization, and embryogenesis take place in the diverticula, which are sac-like outpocketings of the ovariuterine tubules. Formation of a lumen in the diverticulum is indispensable for sperm entry to enable fertilization and subsequent embryogenesis. The aim of the study was to test our hypothesis that the diverticulum lumen forms due to the engagement of the centrally located stalk cells. In this report, we show that in two species of katoikogenic scorpions, at the final stages of oogenesis, the cytoplasm of the stalk cells contains secretory organelles. In the stages preceding fertilization, secretory activity of the stalk cells and fragmentation of their apical parts lead to formation of the diverticulum lumen by a process similar to “cord hollowing” that commonly occurs for lumen formation in other morphogenesis model systems.     

Predispersal mortality and fecundity in the grey mangrove (Avicennia marina) in southeastern Australia

Abstract The predispersal mortality of floral buds and fruits in the grey mangrove (Avicennia marina) was examined over a range of populations for 3 years. The average survival of floral buds to anthesis was 34%. Moth larvae (subtribe Phycitina) attack and consume the contents of variable numbers of flower buds, but their activities did not influence bud survival, as experimental exclusion of larvae did not increase the number of buds surviving to anthesis. Fruit mortality is initially high with an average of 21% of floral buds surviving to immature fruit. Subsequent mortality is lower until on average 2.9% of floral buds survive to become viable propagules. Several cohorts of the phycitine moth larvae feed throughout the development of the fruit, and up to 62% of mature fruit show signs of larval attack. Experimental exclusion of moth larvae doubled the survival of fruits. However more than 75% of fruit mortality may be attributed to maternal regulation. Hail storms can also cause fruit mortality. The potential fecundity (number of ovules) of A. marina was measured over a range of age-size classes of trees and the realized fecundity (viable propagules) was estimated from average predispersal mortality. These estimates were subsequently verified in the field. A fecundity schedule was constructed with assumptions on reproductive frequency and reproductive life. The average annual supply of propagules over a lifetime is estimated to be about 247 viable propagules per tree.     

Winter bud content according to position in 3-year-old branching systems of 'Granny Smith' apple

An investigation was made of the number of preformed organs in winter buds of 3-year-old reiterated complexes of the 'Granny Smith' cultivar. Winter bud content was studied with respect to bud position: terminal buds were compared on both long shoots and spurs according to branching order and shoot age, while axillary buds were compared between three zones (distal, median and proximal) along 1-year-old annual shoots in order 1. The percentage of winter buds that differentiated into inflorescences was determined and the flowers in each bud were counted for each bud category. The other organ categories considered were scales and leaf primordia. The results confirmed that a certain number of organs must be initiated before floral differentiation occurred. The minimum limit was estimated at about 15 organs on average, including scales. Total number of lateral organs formed was shown to vary with both bud position and meristem age, increasing from newly formed meristems to 1- and 2-year-old meristems on different shoot types. These differences in bud organogenesis depending on bud position, were consistent with the morphogenetic gradients observed in apple tree architecture. Axillary buds did not contain more than 15 organs on average and this low organogenetic activity of the meristems was related to a low number of flowers per bud. In contrast, the other bud categories contained more than 15 differentiated organs on average and a trade-off was observed between leaf and flower primordia. The ratio between the number of leaf and flower primordia per bud varied with shoot type. When the terminal buds on long shoots and spurs were compared, those on long shoots showed more flowers and a higher ratio of leaf to flower primordia.     

Influence of synchronization between adult emergence and host plant phenology on the population density of Pseudasphondylia neolitseae (Diptera: Cecidomyiidae) inducing leaf galls on Neolitsea sericea (Lauraceae)

Synchronization between the appearance of herbivorous insects and their host-plant phenology is a critical event, especially for short-lived insects such as gall midges. We studied a natural population of Pseudasphondylia neolitseae (Diptera: Cecidomyiidae) that induces leaf galls on Neolitsea sericea (Lauraceae) to evaluate the effect of synchronization on gall density in the subsequent generation. To do so, we combined quantitative data on host resources with time lag between emergence and host-available seasons. The gamma distribution model was applied to the emergence curve of P. neolitseae and the normal distribution model to the daily changes in the number of host buds suitable for oviposition; the latter model was transformed into an available-resource curve based on the mean number of host buds required for a single female to realize her eggs. By superimposing the emergence curve on the available-resource curve and calculating overlapped area, the degree of synchronization was evaluated more accurately than previous studies, which had treated only the time lag. The number of females that synchronized with host buds affected gall density in the next generation.     

烟粉虱捕食性天敌淡色斧瓢虫的形态特征及生活习性

对淡色斧瓢虫Axinoscymnuscadilobus的形态特征和生活习性进行了观察。在 ( 2 5± 1 7)℃条件下 ,以烟粉虱为食料 ,淡色斧瓢虫完成 1个世代平均历期为 49 5 9d ,成虫的平均寿命为 64 45d ,平均产卵量为 95 4粒 ;淡色斧瓢虫可捕食烟粉虱的卵、若虫、蛹及成虫 ,是烟粉虱的有效天敌 ,具有很好的保护利用价值。     

Sex allocation of females and hermaphrodites in the gynodioecious Geranium sylvaticum

Seed production and patterns of sex allocation were studied in female and hermaphroditic plants in two gynodioecious populations of Geranium sylvaticum (Geraniaceae). Females produced more flower buds and seeds than hermaphrodites in one of the two study populations. The other female traits measured (pistil biomass, seed number per fruit, individual seed mass) did not differ between the gender morphs. The relative seed fitness of hermaphrodites differed between the study populations, with hermaphrodites gaining less of their fitness through female function in the population with a high frequency of females. However, the amount and size of pollen produced by hermaphrodites did not differ between populations. The number of flower buds was positively correlated with seed production in females, whereas in hermaphrodites a positive correlation between number of buds and seed production was found in only one of the two study populations. These results suggest that fitness gain through female function is labile in hermaphrodites of this species, and is probably affected by environmental factors such as the sex ratio of the population.     

Flower bud abortion influences clonal growth and sexual dimorphism in the understorey dioecious shrub Aucuba japonica (Cornaceae)

Sexual differences were investigated to determine the significance of flower bud abortion in the dioecious shrub Aucuba japonica Thunb. The mean number of flowers per inflorescence and the mean number of flowering inflorescences (as opposed to aborted inflorescences) per individual were greater in males than in females in 1997 and 1998. Reproductive investment by males was 0.4-times (1997) and 1.4-times (1998) that by females. In addition, females aborted 30.9% (1997) and 42.7% (1998) of their total flower buds without blooming, whereas no male flower buds aborted. One of the architectural traits of this shrub is that in the year that a flower bud is produced at the shoot apex, the shoot will branch into two or more shoots. Thus, there was less sexual difference in the number of current shoots per individual than there was in the number of flowering inflorescences. The relationship between annual growth and reproduction, and the probability of reproduction in the following year, suggested that the higher investment in female reproduction was manifested as a cost for reproductive frequency rather than as a cost for annual growth. The spatial distribution of both males and females was clumped, which may be the result of clonal growth. In addition, overall sex ratios were not skewed and the number of sprouts did not differ significantly between sexes. These results suggested that flower bud abortion by females might reduce sexual dimorphism in terms of clonal growth.     

江苏沿江棉区3代棉铃虫对棉花的为害及经济阈值

通过人工接虫为害,研究了3代棉铃虫对蕾铃脱落及结铃的影响,观察了不同年份棉铃虫卵和各龄幼虫的自然存活率及棉花蕾、幼铃的成铃率。结果表明,蕾铃的虫害脱落率对结铃的影响最大,直接通径系数达－0.8917,虫量和蕾铃脱落数主要通过接虫期间的虫害脱落率影响棉花结铃,其间接通径系数分别为－0.8894和-0.891,接虫期间的自然脱落率对结铃的直接和间接通径系数均很小,表明33代棉铃虫为害时棉花4的补偿能力已基本丧失,各龄幼虫的为害量观察表明,1－6龄幼虫的单虫为害当量分别为0.02、0.14、0.31、0.47、0.84和1.54个大铃,根据防治的直接和间接收益,得出3代棉铃虫的防治指标为百株累计卵量26粒。     

Osservazioni sul ciclo di sviluppo delle gemme di esemplari mascbili e femminili di Ginkyo biloba L.

Abstract

Observations on the development cycle of the buds of male and female specimens of Ginkyo biloba L. – A study of the buds of long shood and short shoot of male and female Ginkyo biloba L. individuals reveals the following: 1) All the buds of the male individuals are bigger and round in shape while those of the female individuals are smaller and conical. 2) Among individuals of the same sex there are no differences between the buds of long and short shoots except that the latter are always bigger. 3) All the buds, both male and female, show a constant number of buds scales (7–14), embryonic leaves (3–7) and leaf primordia (3–4). 4) The increase in diameters is greater in the male than in the female buds. 5) When opening, the buds of the male short shoots can get as big as 11,5 mm × 11,5 mm and those of the female short shoots 5 mmx4 mm. At this time, the long shoots of both sexes show a less marked differences in size (♂ 5 mm × 5 mm; 9 4 mm × 3,5 mm). 6) The male buds of both long and short shoots are always mixed, that is they are provided with a very small apex and pollen sacs. Only on exceptional cases has sterility been observed. On the other hand female buds are mixed, that is they are provided with a shoot apex and ovules, only in the long shoots of three or more years of age and not always; while the buds of the long shoots are always sterile. 7) Opening of the buds, which in both sexes occurs from the base upwards, takes place at the middle of March in the male and in the first decade of April in the female individuals. 8) The appearence of sex, starting from the base, takes place at an earlier time in male individuals. In fact in the buds of the male short shoots it appears as early as July. In the buds of the female short shoots it appears in October. 9) Pollen cones do not appear at the same time in all the buds of the two types of shoot. They are found in the buds of the short shoots in July, in October in the lateral buds of the long shoots and in November in the terminal buds of the same type of shoots. 10) Ovules appear only in some buds of short shoots three or more year old. They are never present in the long and short shoots one or two year old buds. 11) The dates of appearance of the pollen cones and ovules in our Florentine specimens are exactly the same as those reported by SPRECHER (1907) for the Ginkyo plants growing in Geneva.     

Sexual dimorphism and fruit production in a dioecious understory tree,Ilex opaca Ait.

Summary This study suggested that sexual selection is potentially an important factor in the maintenance of dioecy in the American holly, Ilex opaca (Aquifoliaceae). Sexual dimorphisms in flower production and phenology were highly significant in this understory tree. On average, individual males produced 7.4 times as many flowers as did female trees. Staminate flowers lasted only a single day, whereas pistillate flowers lasted 3–4 days, during which they showed no significant decline in their ability to produce fruit after pollination. Individual male trees opened their flower buds asynchronously during the season, maximizing the number of days they were in flower. Individual females opened their buds more synchronously, maximizing their floral display at one point in time. Females produced fruits in numbers that were somewhat less than proportional to their flower production. Fruit development was initiated from only 38.9% and 69.5% of pistillate flowers in 1987 and 1988, respectively. By the time of ripening, an average female had lost 62.3%, 24.3%, and 11.1% of its initial fruit crop in 1986, 1987, and 1988, respectively. The proportion of fruit lost in 1986 was independent of the number of fruit that initially began development. In 1988, artifically supplementing pollen to a large number of flowers failed to increase either fruit or seed production relative to control branches with unsupplemented flowers. This suggested that resource levels were likely more important than pollen availability in limiting female reproductive success. These observations on I. opaca were consistent with the expectations for a population in which male reproductive success continues to benefit from continued pollinator service and female reproductive success does not.     

Contribution to the biology of the citrus bud mite, Aceria sheldoni (Ewing) (Acarina: Eriophyidae)*

In laboratory studies mites of Aceria sheldoni were reared on citrus fruit peels, beneath coloured cellophane hoods, to cater for their thigmotaxis and sensitivity to light of particular wave lengths. Hatching was most successful at 25°C and 98% r.h. but was reduced by low humidities (35–40% r.h.), when abnormal dwarf larvae emerged. The eggs hatched in 3–14 days; the length of a generation (egg to egg) was 12–33 days. The threshold of embryonic development was 9 °C and that for completion of the life cycle, egg to egg, was 12.5 °C. The average number of eggs laid per female was six (4–8). It increased to twelve (5–19) if the mite, during its larval stages, had been fed on buds. The vitality of both the eggs and the mature mites was tested by exposure to extreme low and high temperatures (below 0 °C, 39 °C): 50% of mites died after 30 min at 30 °C; 50% died after 30 min at –15 °C or lower.     

Functional morphology of the taste buds of Florida manatee,Trichechus manatus latirostris

The Florida manatee, Trichechus manatus latirostris, is a fully aquatic, threatened marine mammal for which increased understanding of their physiology, reproduction, and nutrition supports management decisions. Manatees may use taste to distinguish saltwater gradients, toxin detection, food assessment, and social interactions. This study sought to locate and characterize manatee taste buds comparing location, structure, number, and size to other species. Entire heads from manatees (6 males, 4 females) of various ages were obtained. The muzzle, tissue surrounding the nares, oral cavity, and epiglottis were examined grossly for pits and papillae. Tissues were examined using light and transmission electron microscopy. Within the predominant taste bud location, the tongue root, taste bud number was estimated using samples from four animals. The average number of taste buds within the tongue root was 11,534 (range 2,711–23,237) with sparse taste buds located on the soft palate and epiglottis. The location along the lateral surface of the tongue root and bordered by grooves, through which tastants could be easily transported, has functional significance. Large numbers of taste buds within the tongue root suggest that taste is an important component of manatee sensory systems and behavioral research would clarify this.     

Life history of the mealybug, Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), at constant temperatures

Important life history parameters of the mealybug, Maconellicoccus hirsutus (Green), were characterized on hibiscus (Hibiscus rosa-sinensis L.) cuttings at six constant temperatures between 15 and 35 degrees C. The development of M. hirsutus was the fastest at 27 degrees C, where the mealybugs completed development in approximately 29 d. The lower (T(min)) and upper (T(max)) developmental thresholds and the optimal developmental temperature (T(opt)) for the development of female mealybugs were estimated as 14.5, 35, and 29 degrees C, respectively. The thermal constant (K), which is the number of temperature-day or degree-day units required for development, of the females was 347 DD. The original distribution range prediction (based on T(min) = 17.5 degrees C and K = 300 DD) indicated that M. hirsutus could complete at least one generation in all of the continental United States. However, results of this study suggested that the distribution range of M. hirsutus may expand northward because of the lower T(min), and the predicted number of generations in a year may be lower because of the higher K required to complete each generation. The average cumulative survival rate of M. hirsutus at 25 and 27 degrees C was 72%, which was significantly higher than 51 and 62% at 20 and 30 degrees C, respectively. M. hirsutus reproduced sexually, with each mated female producing 260-300 eggs between 20 and 27 degrees C but only approximately 100 eggs at 30 degrees C. Female longevity was reduced from 28 d at 20 degrees C to 19-21 d at 25-30 degrees C. At 27 degrees C, the net reproductive rate (R(o)) was estimated at 165 female symbol/female symbol, the intrinsic rate of population increase (r(m)) was 0.119 (female symbol/female symbol/d), the generation time (T(G)) was 43 d, and the doubling time (DT) was 5.8 d. The life table statistics suggested that the currently released biological control agents, which have higher r(m) than M. hirsutus, will be able to complete more generations than the mealybug within the tested temperature range; thus, they are effective against M. hirsutus.     

Effect of modified endogenous ethylene production on sex expression, bisexual flower development and fruit production in melon (Cucumis melo L.)

Members of the Cucurbitaceae family display a range of sexual phenotypes including various combinations of male, female, or bisexual flowers. Ethylene appears to be a key hormone regulating the sex determination process. Application of ethylene, or inhibition of ethylene action, increases or decreases the number of pistil-bearing buds, respectively. Elevated levels of ethylene production and expression of genes for ethylene biosynthesis, have been correlated with pistillate flower production. In this study, we sought to determine the effect of modified endogenous ethylene production on sex expression by constitutively expressing ACS (1-aminocyclopropane-1-carboxylate synthase), the first committed enzyme for ethylene biosynthesis, in transgenic melons (Cucumis melo L.). Most melon genotypes are andromonoecious, where an initial phase of male flowers is followed by a mixture of bisexual and male flowers. ACS melon plants showed increased ethylene production by leaves and flower buds, and increased femaleness as measured by earlier and increased number of bisexual buds. ACS melons also had earlier and increased number of bisexual buds that matured to anthesis, suggesting that ethylene is important not only for sex determination, but also for development of the bisexual bud to maturity. Field studies showed that ACS melons had earlier mature bisexual flowers, earlier fruit set, and increased number of fruit set on closely spaced nodes on the main stem. These results provide a direct demonstration of the importance of endogenous ethylene production for female reproductive processes in melon.     

Promotion of flowering in the Pinaceae by gibberellins

Significant male and female flowering (cone bud production) by girdled branches of 6-year-old Douglas fir (Pseudotsuga menziesii (Mirb. Franco) seedlings was promoted by applications (mid-April to June) of 1.6 or 3.2 mg per branch (in total) of certain non-polar gibberellins (GA's). Girdling alone was ineffective. When tested alone, a mixture of GA_4/7 was most effective. GA₉ less so, while GA₅ and the more polar GA₃ were essentially ineffective. For female cone buds GA_4/7+ GA₉ were synergistically effective, but for male cone buds GA_4/7 alone was best. The auxin naphthaleneacetic acid (NAA) was not tested alone, but at low dosage (0.175 mg/branch in total) NAA enhanced the flowering efficacy of GA's for both sexes; at a high dosage (0.875 mg/branch in total) male cone bud production was further enhanced, but only at the expense of females. For female flowering the best treatment (90% frequency of flowering 6.8 cone buds/branch), was GA_4/7+ GA₉+ low NAA; for male flowering, it was GA_4/7+ high NAA (30% frequency and 4.2 cone buds/branch. Frequency of flowering for controls was 18% and 0%, average number of cone buds/branch was 0.9 and 0, for females and males, respectively. The successful treatments did not affect promordia initiation, rather they caused the differentiation of previously initiated, but undetermined, lateral primordia into cone and latent buds at the expense of vegetative bud differentiation. The lack of success reported by earlier workers in promoting flowering in Pinaceae species by GA's appears to be the unfortunate result of selecting GA₃ for initial testing. The practical implications of this early and enhanced flowering by non-polar GA's seedlings of a commercially important conifer are discussed in relation to accelerating the processes of tree improvement.