Feeding behavior and reproduction of Stenophthalmus wagneri Tifl., 1928 (Stenophthalmidae, Siphonaptera) under experimental conditions]

Under laboratory conditions at 20 to 21 degrees C young imagos of C. wagneri proceed quickly to feeding and reproduction. They suck blood about three times a day and females oviposit three times, each laying consisting of three eggs. When placed in a refrigirator at 2 to 5 degrees some young individuals lay eggs, while others do not start oviposition up to 5 months (observation period). Fleas, which already laid eggs under laboratory conditions, being transferred into a refrigerator decrease the degree of their attachment to the host and feeding frequency (up to one time a day). Oogenesis of females is inhibited and most of them cease egg laying.     

Experimentally induced clutch size enlargements affect reproductive success in the Pied Flycatcher

We performed a food provisioning experiment in a population of Pied Flycatchers Ficedula hypoleuca breeding at high altitude in central Spain to test if food availability before and during laying determines clutch size. Food was provided to one of two pairs with the same date of initiation of nest-building (15 dyads of subsequently reproducing pairs were thus created). Food provisioning began on the day of initiation of nest-building and ended on the day after the last egg was laid. Although laying date was unaffected by the experiment, clutch size in the experimental treatment was significantly larger. This result could indicate that food availability at laying (1) proximately constrained clutch size or (2) that females evaluated future conditions for incubating eggs and feeding nestlings based on food availability at laying. Reproductive success (proportion of eggs that resulted in fledged young) was significantly reduced in the experimental treatment. This effect suggest that supplemented females were tricked by the experiment into laying more eggs than the number of eggs they were able to incubate with success and the number of nestlings they were able to feed, a source of error in clutch size adjustment which could be common in non-experimental situations.     

柳蓝叶甲的生物学特性室内观察

在实验室条件下(27±0.5℃,12 D:12 L)研究了柳蓝叶甲Plagiodera versicolora的生物学特性。结果表明,幼虫每隔2~3 d蜕皮1次,共蜕皮2次。成虫产卵前期4 d,世代周期17 d。产卵具有一定的周期性,约10 d为1个周期。叶龄对幼虫的生长发育和成虫的产卵行为有极显著的影响。当幼虫以成熟叶为食料时,其生长发育速率明显减慢,各龄期延长,蛹重较轻;成虫以成熟叶或老叶为食料时产卵几乎完全被抑制,而以幼叶为食料时几乎每天均能产卵。此外,柳蓝叶甲产出卵表面化合物对产卵行为有极为显著的影响。卵表面的有机提取物对成虫产卵具有显著的引诱作用;相反,卵表面的水提取物对产卵有一定的驱避作用。     

Cultivation of the mosquito Culex pipiens pipiens f. molestus (Diptera, Culicidae) without blood feeding

Optimal photoperiod and temperature conditions for rearing of the mosquito Culex pipiens pipiens f. molestus without blood feeding (through autogenous eggs) were experimentally substantiated. This method may be used in order to obtain relatively small quantities of mosquitoes or for preservation of a laboratory colony. Optimal conditions of rearing are the short-day photoperiod (12 h of light per day) at 20 degrees C, when 87 % of the females produce autogenous eggs rafts consisting of 52 eggs on the average. It should be emphasized that larval food must be adequate and abundant, because the quality and quantity of it has a pronounced effect on the autogeny rate.     

An individual-based model for predicting the emergence period of sea trout fry in a Lake District stream

The objective of this study was to predict interannual fluctuations in the emergence period of sea trout fry, using models developed from field data for 70 excavated redds, and laboratory data on egg and alevin development at 30 constant temperatures (range 1·5–10·5° C with 100 naturally fertilized eggs at each temperature). Egg weight and numbers per redd both increased with female length; a power function described the relationship. Early spawners were the largest females laying the largest and most numerous eggs, whilst late spawners were the smallest females laying the smallest and least numerous eggs; middle spawners being intermediate between these two extremes. Mean values for egg weight and numbers of eggs per redd were obtained for these three groups. Hatching and emergence times in the laboratory decreased with increasing temperature. Of five models tested for hatching time, the best fit was provided by a three-parameter hyperbolic model which formed the asis of the individual-based model used to predict egg hatching and fry emergence. Model development was described in detail and the final equations predicted the times taken for 5, 50 and 95% of the fry to emerge, and hence the period over which 90% of the fry emerged. Analogous models were obtained for egg hatching. All models were excellent fits to the laboratory data. Hatching times for eggs kept in perforated boxes in the stream were almost identical to those kept at similar mean temperatures in the laboratory. Model predictions of fry emergence times were validated by field data for 8 years (1967–1971, 1974, 1975, 1980). The chief objective was therefore fulfilled, and predictions for the 30-year study (1967–1996) revealed a large variation in the timing of emergence (extremes: 11 March–4 April 1989, 15–20 May 1979). Most of the variation in median emergence date was due to variations in water temperature, with spawning dates as a secondary factor; the latter, however, had a greater effect on the length of the emergence period.     

Effect of food and temperature on the reproduction of the blowfly, <Emphasis Type="Italic">Calliphora vicina</Emphasis> R.-D. (Diptera,Calliphoridae), a popular model object in biological research

Egg maturation in Calliphora vicina is known to occur within a wide range of temperatures, from 12°C to nearly 30°C (Vinogradova, 1991). Photoperiodism has no effect on this process. Some females enter diapause already at 20°C; their fraction increases at lower temperatures and reaches 100% at 6°C. Reproducing females with eggs can survive for a long time and even lay eggs at low temperatures (4–5°C). Experiments with C. vicina from Leningrad Province revealed some effects of the diet (liver or fish) and temperature on the fly reproduction. At 20 and 25°C, 7–10-day old females begin to oviposit, but at 20°C egg maturation is observed in 98% of females feeding on liver and in only 5% of females feeding on fish. On the liver diet, the mean daily fecundity is significantly correlated with the day of oviposition but not with the temperature. At 20°C a significant correlation is observed between the mean daily fecundity and both the day of oviposition and food. The total number of eggs laid by flies after feeding on fish is half that produced after feeding on liver. The optimal conditions for Calliphora vicina cultivation are a 16-h light day, temperatures within the range from 20 to 25°C, and liver as food.     

Biology of Agistemus brasiliensis Matioli, Ueckermann & Oliveira (Acari: Stigmaeidae) and its predation potential on Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae)

The present work aimed to study the biology of Agistemus brasiliensis Matioli, Ueckermann & Oliveira at the following temperatures, namely 15, 20, 25, 30 and 35 degrees C, fed with Brevipalpus phoenicis (Geijskes) and Typha pollen, in laboratory conditions. Life tables were calculated to evaluate the biological parameters. The optimal development of A. brasiliensis took place at 29 degrees C. The values of T (time of generation - days), R0 and r m at 30 degrees C were, 13.95, 16.25 and 0.20, respectively. The prey consumption of A. brasiliensis was studied at the densities of 5, 10, 20, 40 and 60 leprosis mite females per cage (3 cm in diameter) on citrus fruits at 29 degrees C. The maximum prey, namely 7.6 B. phoenicis females per day, were consumed at a density of 20 leprosis mites. At densities of above 40 leprosis mites per cage, A. brasiliensis oviposits 4.7 eggs per day, in comparison to 2.5 eggs per day at 20 mites per cage.     

Photoperiodic,thermal and trophic responses of a predatory ladybird Cheilomenes propinqua

Large geographic range, wide habitat specificity and broad range of prey (including a number of pests of protected crops) suggest that a predatory ladybird Cheilomenes propinqua can be considered as potential agent for biological control in greenhouses. We investigated the influence of day length (10, 12 and 14 hr), temperature (20 and 24°C) and diet (the green peach aphid Myzus persicae and eggs of the grain moth Sitotroga cerealella) on the rate of maturation, fecundity and induction of reproductive diapause in C. propinqua females of a laboratory population originated from Alexandria, Egypt. The proportion of diapausing females (i.e. those with poorly developed ovaries and well-developed fat body) varied from 5% to 70% being higher at short day, low temperature and feeding on the grain moth eggs. This diapause, however, was not very stable: more than 20% of females kept under diapause-inducing conditions started to lay eggs during 110 days, although their pre-oviposition period was about 5 times longer than that of females which matured at the same temperature but at the long day and on the natural diet. Although not very stable, reproductive diapause significantly increased survival of starving females. Such a short-term reproductive diapause can be considered as an adaptation to mild and short-term subtropical winter. The results of our study suggest that C. propinqua mass rearing will be more intensive at the combination of high temperature, natural food (aphids) and long day (14 hr), whereas individuals intended for long-term storage should be reared under moderate temperature (20°C) and short-day (10 hr) conditions and should be fed on factitious food (the grain moth eggs).     

Inter- and intraspecific predation on immatures by adult females in Euseius finlandicus, Typhlodromus pyri and Kampimo dromus aberrans (Acari: Phytoseiidae)

In a series of experiments, the interspecific predation and cannibalism on immatures by the adult females of Euseius finlandicus, Kampimodromus aberrans and Typhlodromus pyri were examined under laboratory conditions. The three species showed differing tendencies to prey on each other's motile immature stages. Euseius finlandicus females consumed more larvae and protonymphs than the females of T. pyri and K. aberrans. In cages without free water E. finlandicus ate a range of 6.51 larvae or 5.31 protonymphs of T. pyri and 5.27 larvae or 5.95 protonymphs of K. aberrans per female per day. Kampimodromus aberrans and T. pyri females exhibited a greater tendency to prey on heterospecifics than on conspecifics. When feeding on phytoseiid immatures and without free water, T. pyri females survived longer and laid more eggs than the females of E. finlandicus and K. aberrans. Adult females of E. finlandicus and T. pyri having free water and preying on heterospecific protonymphs were able to maintain egg laying during the whole experimental period of 12 days. The females of all three species had difficulties in piercing phytoseiid eggs, and the number of sucked eggs per female per day was low. Kampimodromus aberrans females ate 0.48 eggs of T. pyri daily, which was the highest recorded number. The great tendency to interspecific predation on motile immature phytoseiids by the females of E. finlandicus is discussed with regard to the dominance of this species on deciduous trees and bushes in Austria.     

Levels of ecdysteroids in diapause and non-diapause eggs of the Australian plague locust,Chortoicetes terminifera (Walker)

The levels of ecdysteroids during embryogenesis in Chortoicetes terminifera were measured by radioimmunoassay. Soon after laying, eggs laid by females reared under non-diapause conditions contained three times as much as those laid by females reared under diapause inducing conditions. In eggs incubated at 32°C which did not enter diapause there was a sharp rise in ecdysteroid levels which coincided with the formation of the first-instar cuticle, but this did not occur in eggs incubated at 20°C even though they developed and hatched normally. Comparisons are made with previous results in other locust species and the possible role of ecdysteroids in embryonic diapause is discussed.     

Effects of crowding, isolation, and transfer from isolation to crowding on total ecdysteroid content of eggs in Schistocerca gregaria

We examined the ecdysteroid content of eggs from crowd-reared and solitary-reared desert locusts, Schistocerca gregaria, throughout embryogenesis from the day of egg laying until shortly before hatching on day 14. Depending on the time during incubation, ecdysteroid content in eggs from crowd-reared females was 5-10 times higher than in eggs from solitary-reared females. Our investigation revealed two peaks in ecdysteroid content of eggs from crowd-reared females, a small one at day 3 and a major peak at day 10 of incubation. At days 10, 12 and 14 during incubation of eggs from crowd-reared females, we found a positive correlation between egg mass and ecdysteroid content. There was no difference between eggs from the bottom and the top of individual egg pods, but variation in ecdysteroid content between egg pods from different females was considerable in all treatment groups. A brief crowding of solitary-reared females at the time of egg laying, a treatment that initiates maternally mediated gregarization of the developing offspring, had no effect on the consistently low ecdysteroid content in the eggs. This result rules out the possibility that the crowding experience of females is transmitted to the offspring by variation in the total amount of ecdysteroids in their eggs.     

Multiple matings increase the fecundity of the yellow swallowtail butterfly,Papilio xuthus L., in summer generations

Females of the yellow swallowtail butterfly, Papilio xuthus,were reared in the laboratory. They were divided into four groups held under different mating conditions: nonmating (virgin) and mated once, twice, and three times. The number of eggs in the ovaries was counted by dissection. Virgin females produced increasing numbers of mature eggs, up to about 30, in the week following emergence. When the female had mated once, the number of mature eggs was significantly higher than that of virgin females by the second day after emergence. However, the double- and triplemated females did not increase the number of eggs in each state further than the singlemated females. The double-mated females deposited significantly more eggs than the singlemated females in the laboratory. The triplemated females also deposited more eggs on the day after the third mating than the doublemated females. Thus, multiple matings increased the number of eggs deposited. The change in the hatchability and the morphology of the spermatophore in the bursa copulatrix suggested that the sperm from the last mating had precedence.     

Effect of mating period and time‐of‐day for bloodmeal on rearing of Asian tiger mosquito (Aedes albopictus) in laboratory conditions

Colonization and maintenance of mosquitoes in the laboratory is required to study physiology, ecology, and behavior of mosquitoes and interactions between mosquito and pathogens. Artificial blood feeding systems have been widely used to maintain the laboratory colony of Aedes albopictus. In this study, we investigated the effects of mating period (1, 3, 6, and 10 days) and time‐of‐day for bloodmeal (08:00, 13:00, and 18:00) in the use of an artificial feeding system on blood‐feeding rate, female fecundity, egg hatching rate, and developmental time of the Asian tiger mosquito, A. albopictus. Younger females mated for three or fewer days reproduced more eggs compared to those of oldest females mated for ten days. Similar to the result for eggs laid, the mean egg‐hatching rate was significantly higher from the offspring of younger females than from those of older females. However, mating period and time‐of‐day for bloodmeal had no effect on the blood feeding rate and developmental time. Taken together, we suggest that three‐day mating with bloodmeal at 18:00 is optimal for maintaining colonies of A. albopictus in laboratory conditions.     

Reproductive potential of overwintering, F1, and F2 female boll weevils (Coleoptera: Curculionidae) in the Lower Rio Grande Valley of Texas

The feeding and oviposition activity of overwintering boll weevils, Anthonomus grandis grandis (Boheman), and seasonal fluctuations in development, survival, and reproduction of progeny of overwintering and first- and second-generation boll weevil females were determined in the laboratory at 27 degrees C, 65% RH, and a photoperiod of 12:12 (L:D) h. During the cotton-free period in the Lower Rio Grande Valley, female boll weevils without access to cotton resorb their unlaid eggs and enter reproductive diapause. However, when they were provided daily with greenhouse-grown cotton squares, commencement of oviposition began after 7, 15, or 20 d, depending on when they were captured. Females captured later in the winter fed longer before laying eggs than those captured in the early fall, suggesting that it may take females longer to terminate diapause the longer they have been dormant. The rate of feeding by females was significantly less during the winter months, and this may have affected the rate of diet-mediated termination of dormancy. Females of the first and second generations after the overwintering generation produced a significantly higher percentage of progeny surviving to adulthood and a higher proportion of these progeny were females. Offspring development time from overwintering female parents was significantly longer than that from first and second generations under the same laboratory conditions. The total number of lifetime eggs produced by females of the second generation during the cotton-growing season were approximately 9.9-fold higher than for overwintering females and 1.5-fold higher than for first-generation females. Life table calculations indicated that the population of second-generation boll weevils increased an average of 1.5-fold higher each generation than for females of the first generation and 22.6-fold higher than for overwintering females. Our data showed variation in boll weevil survival, development, and reproductive potential among the overwintering and first- and second-generation females, suggesting inherent seasonal fluctuations in these parameters.     

Aging and changes in fecundity of the flea Leptopsylla segnis (Siphonaptera: Leptopsyllidae)

In experiment, the mean diurnal fecundity of Leptopsylla segnis females increased during the first five days since the beginning of feeding on white mice and reached the maximum in the second five-day period (15.7-16.7 eggs per 1 female during a day). In subsequent period of stay on a host, an activity of egg laying gradually decreased. In flea females, which had lived on hosts for 40 days and more this index was 3.7 eggs. During the mean life longevity (23 days), the flea females lay about 260 eggs; the females, which have lived more than 40 days, produce above 400 eggs.     

Effects of temperature on energy cost and timing of embryonic and larval development of the terrestrially breeding moss frog, Bryobatrachus nimbus

The Australian moss frog, Bryobatrachus nimbus, oviposits four to 16 large eggs in terrestrial nests constructed in moss or lichen in subalpine regions of southern Tasmania. Nidicolous larvae overwinter beneath snow, reaching metamorphosis without feeding after 395 d, the longest development time known for an endotrophic anuran. However, a few clutches develop more quickly and metamorphose before winter. This study examines the effect of temperature on development time and energy expenditure by measuring temperatures and developmental stages in field nests as well as rates of oxygen consumption (Vo2), developmental stage, body mass, and energy content in the laboratory at three relevant temperatures (5 degrees, 10 degrees, 15 degrees C). Eggs and larvae reared at 5 degrees C differentiated very slowly, and their development time far exceeded those in natural nests, but development times at 10 degrees and 15 degrees C averaged 277 and 149 d, respectively, and were shorter than field incubation times. Generally, respiration rates of aquatic hatchlings were low in comparison with other species but increased with larval age and jumped about 25% higher near metamorphosis when larvae were able to air breathe. The mean energy density was 26.0 J mg(-1) for the dry ova and 20.6 J mg(-1) for a dry gut-free froglet, and total production efficiency was 61.5%. We developed a model based on the relationships between incubation temperature and V&d2;o2 to estimate the respiratory cost of development to metamorphosis, the first such study for an amphibian. The cost was 177 J at 15 degrees C, 199 J at 10 degrees C, and at least 249 J at 5 degrees C, and we predicted that continual development at 5 degrees C would lead to premature yolk depletion because it equalled the 249 J contained in fresh ova. Continuously logged field-nest temperatures and interpolation of laboratory data provided estimates of development rates, Vo2, and respiratory energy costs in field nests. Development to metamorphosis required between 185 and 234 J when larvae overwintered, but completion of metamorphosis before winter saved 123 J. However, the advantage of emergence in warmer months, when conditions are suitable for feeding and growth, may offset the greater energy cost of overwintering.     

Patterns of variation in size of Boat-tailed Grackle Quiscalus major eggs

Boat-tailed Grackle Quiscalus major eggs averaged 8^.09 g wet weight. Mean egg weight represented 8 05 % of female body weight. Based on egg weight, Grackle eggs have a shorter incubation period than the general passerine pattern.
Egg weight varied significantly with sequence of laying and between clutches in both two-egg and three-egg clutches. Last laid eggs weighed less than first laid eggs. The mean weight of the first two eggs laid in three-egg clutches did not differ from the mean egg weight of two-egg clutches. The average clutch of two and three eggs weighed 16.33 g and 24.16 g, respectively.
Mean egg weight varied between study colonies and with season. Grackles at East Lake laid eggs that weighed less than grackles at either Alligator Lake or North Lake. Eggs laid during March averaged less than eggs laid later in the season. The locality variation reflects the different timing of nesting between sites rather than food abundance. As nutrient provisioning increases with an increase in egg weight, the seasonal change in egg weight probably reflects improved feeding conditions for the female. This suggests that selection favours beginning laying before reserves of the female are sufficient to lay the largest egg possible.
The size of the young at hatching was correlated with egg size. Newly hate had young averaged 79.6% of fresh egg weight. Egg weight did not determine the probability of hatching or starvation of the young. Females do not appear to adjust egg size facultatively depending on the sex of the young. Eggs producing males and females did not vary significantly in weight, whether comparisons were made within or between clutches.     

The effects of low temperature on Lymnaea truncatula.

A group of 20 young and another of 20 adult Lymnaea truncatula were abundantly supplied with food and kept continuously under cold conditions (5 degrees C) in the laboratory for 3 months and the effects of low temperature on their behavior, growth and reproduction were studied. The results indicate that at low temperature the activity of L. truncatula was markedly reduced but complete hibernation did not occur. The snails seem to be unaffected by the low temperature itself since none (both young and adult) died during the 3 months that they were kept at 5 degrees C. Reduced feeding, even in the presence of abundant food, during the cold conditions caused an almost total inhibiton of growth. Of even more significance was the suppression of reproduction which was connected with the metabolic rate of adult snails kept at low temperature. Young snails seem to profit by exposure to low temperature. On the return to normal laboratory temperature (16-22 degrees C) the young snails became very active, fed voraciously, grew rapidly, tended to live longer and produced more offspring than the controls. Low temperature, however, appears to have an adverse after-effect on the growth and reproduction of mature snails. Relatively, fewer eggs were deposited in this case. The results indicate that under natural field conditions in England, where temperature fluctuations during the usually mild winter months are common, the greater burden of increasing the population in overwintered snails must rest on the younger members of the community.     

Biology of Ixodes (Pholeoixodes) hexagonus under laboratory conditions Part II. Effect of mating on feeding and fecundity of females

The effect of mating on the feeding and fecundity ofIxodes (Pholeoixodes) hexagonus females was studied under controlled laboratory conditions of 22–23°C and 98% relative humidity. The feeding period of mated females was 6–15 days and 11–13 days for unmated females. The mean weight of the engorged mated females was 114.84±45.89 mg, whereas, that of the engorged unmated females was significantly lower (80.61±28.84 mg). During the initial slow feeding period, the weight of mated females increased 6.6 times. At the end of the blood feeding, they had increased their initial weight 35.5 times. Unmated females never entered the rapid engorgement phase and up to 12 days of feeding period their mean weight did not increase more than 9.2 times. The pre-oviposition periods of mated and unmated females were 6–15 days and 4–12 days, respectively. The mean of the egg production efficiency was 40.26±12.47% for mated females and 35.68±12.2% for unmated females. The mean of the mass conversion efficiency was 73.6±13.7% for mated females and 66.48 ±16.55% for unmated females. Sixty per cent of the eggs deposited by mated females hatched whereas only 1% of the eggs deposited by unmated females hatched. These results indicate thatI. hexagonus females possess some predisposition for parthenogenesis and only fertility and not fecundity depends on mating.     

Relative reproductive success of female moorhens using conditional strategies of brood parasitism and parental care

In a population of moorhens (Gallinula chloropus), at least27% of netting females laid one or more eggs in a neighbor'snest Females laid parasitically under three conditions: 56%of parasitic eggs were from nesting females that preceded layinga dutch in their own nest by a parasitic laying bout, 19% werefrom females whose nests were depredated before clutch completionand that laid the following egg parasiticaDy, and 25% were froma small number of females without territories, "non-nesting"parasites, that each laid a series of parasitic eggs. Clutchsizes varied greatly between females, but nesting females eachlaid a consistent clutch size both within and between seasonsfor a given mate and territory. Nesting females that employeda dual strategy of brood parasitism and parental care producedextra eggs that they laid in the nests of neighbors before layinga dutch in their own nests. Two out of ten females whose dutchesI experimentally removed during the laying period were successfullyinduced to lay their next egg in the nest of a neighbor. Nestingfemales that laid parasitically selected their hosts opportunisticallyfrom among the nests dosest to their territories. An experimentin which parasitic eggs were removed and hosts left to rearonly their own young showed that parasites did not choose hoststhat were better parents than pairs with contemporary neststhat were not parasitized. Females that only laid parasiticaDywithin a given season timed their parasitic laying bouts poorlyand achieved no reproductive success. Parasitic young rarelyfledged, and the mean seasonal reproductive success of nestingbrood parasites did not differ from that of nonparasitic females.However, the variance in reproductive success of nesting broodparasites was significantly higher than that of nonparasiticfemales.