Significant Reduction In Fecundity Research Articles

Conditional tradeoffs between aging and organismal performance of Indy long-lived mutant flies.

Alterations that extend the life span of animals and yeast typically involve decreases in metabolic rate, growth, physical activity, and/or early-life fecundity. This negative correlation between life span and the ability to assimilate and process energy, to move, grow, and reproduce, raises questions about the potential utility of life span extension. Tradeoffs between early-life fitness and longevity are central to theories of the evolution of aging, which suggests there is necessarily a price to be paid for reducing the rate of aging. It is not yet clear whether life span can be extended without undesirable effects on metabolism and fecundity. Here, we report that the long-lived Indy mutation in Drosophila causes a decrease in the slope of the mortality curve consistent with a slowing in the rate of aging without a concomitant reduction in resting metabolic rate, flight velocity, or age-specific fecundity under normal rearing conditions. However, Indy mutants on a decreased-calorie diet have reduced fecundity, suggesting that a tradeoff between longevity and this aspect of performance is conditional, i.e., the tradeoff can occur in a stressful environment while being absent in a more favorable environment. These results provide evidence that there do exist mechanisms, albeit conditional, that can extend life span without significant reduction in fecundity, metabolic rate, or locomotion.

Reproduction and population sexual structure of the overexploited Mediterranean red coral Corallium rubrum

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 248:99-108 (2003) - doi:10.3354/meps248099 Reproduction and population sexual structure of the overexploited Mediterranean red coral Corallium rubrum G. Santangelo*, E. Carletti, E. Maggi, L. Bramanti Dipartimento Etologia, Ecologia, Evoluzione, University of Pisa, Via Volta 6, 56126 Pisa, Italy *Email: sant@deee.unipi.it ABSTRACT: This study provides the first description of the reproductive features of a red coral Corallium rubrum population. This circum-Mediterranean octocoral has been over-harvested and commercial stocks are depleted. The population we studied was gonochoric at both the colony and polyp levels, and its sex ratio was significantly biased toward females. The minimum age at first reproduction was 2 yr. The percentage of fertile colonies increased with age, reaching 100% fertility for those over 5 yr. Due to the low frequency of older colonies, 2/3 of the population was unreproductive. The seasonal cycle of oocyte maturation resulted in a rapid increase in diameter after March, corresponding to a significant reduction in fecundity and fertility. Larval release occurred between late July and August, and settlement ended by mid-September. No significant difference was found in fecundity or fertility between colonies living at different depths (25 and 35 m). Both reproductive parameters depended on polyp position on the colony branches, being significantly lower in the tips of 1st order and proximal parts of 2nd order branches. Due to these opposing trends, no significant overall difference was found between branches of different orders. Female polyp fecundity (0.87 gonads per polyp) was considerably lower than fecundity measured in other octocorals, and the larval production depends on the size/age of the colony: while reproductive colonies in Class 2 (diameter 1.82 mm) produce on average 24 planulae, the larger, older colonies in Class 6 (diameter > 4.6 mm) produce 157 planulae on average. This clearly indicates large differences in larval production between populations with different size and/or age structures. A better understanding of red coral reproduction will help to match harvesting levels to recovery rates in overexploited populations. KEY WORDS: Red coral · Octocorallia · Sexual structure · Reproduction · Mediterranean Sea Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 248. Online publication date: February 20, 2003 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2003 Inter-Research.

Vaccination with neutrophil inhibitory factor reduces the fecundity of the hookworm Ancylostoma ceylanicum.

Neutrophil inhibitory factor (NIF), a protein isolated from hookworms of the genus Ancylostoma, inhibits CD11b/18-dependent leucocyte function, binding to the I domain of CD11b. Historically, NIF was serendipitously isolated from whole worm extracts during a search for novel antihaemostatic agents, and little is known of its source or biological significance to the parasite. NIF has also been identified as a possible hookworm vaccine candidate. Ancylostoma ceylanicum recombinant NIF, expressed in its active form in Pichia pastoris, was purified and its functional activity confirmed using neutrophil adhesion assays and confirmatory immunoassay. Recombinant NIF was subsequently used in vaccination trials in the A. ceylanicum-hamster model system for human hookworm infection. Vaccinated and challenged animals were not protected in terms of worm burden or haematocrit values, despite the presence of high levels of specific antibody against NIF. However, adult worms resident in vaccinated animals showed a significant reduction in fecundity (85.8% by day 21 postinfection), indicating a degree of protection against subsequent transmission by vaccination. These data indicate that targeted vaccination with recombinant subunit material, derived from a known and effective immune suppressant secreted by the parasite, may offer partial protection against the transmission of hookworm infection. Furthermore, we can also report that a biological activity characteristic of NIF is detectable in the secretions of A. ceylanicum using two complementary bioassays. Complete neutralization of this secreted activity by vaccination in combination with other vaccine candidates may result in improved protection against A. ceylanicum infection.

COLONY INTEGRATION DURING REGENERATION IN THE STONY CORALFAVIA FAVUS

Modular organisms consist of repeated building blocks. An important con- sequence of modularity may be reflected in the ability of a colony to continually reallocate priority of resource transport among its units in response to stress. Hermatypic corals, the main organisms constructing tropical reefs, are prone to damage by a multitude of agents. Since colonization of lesions by competitors is a potent threat to colonial organisms, fast recovery is an important component of colony survival. Previous regeneration studies have claimed that the energy requirements of this essential process are fueled only by the polyps directly bordering the injured area. This ''localized regeneration hypothesis'' rejects the necessity for wide colony integration during regeneration and sees no advantage to large colony size. The objective of the present study was to test an alternative regeneration hypothesis that argues, in contrast, that injury repair (i.e., closure of lesions by newly formed tissues) in corals may require extended colony integration (i.e., internal translocation of resources from sites of acquisition to sites of maximal demand). To test our hypothesis we examined: (1) the relationship between colony size and percentage recovery of lesions differing in size and shape; and (2) the effect of different sized lesions on the fecundity of polyps located at increasing distances from the lesion site. Both experiments were conducted on the common, spherically shaped coral Favia favus in the Red Sea near Eilat, Israel. The relatively small lesions ( , 1c m 2 ) were the only ones to support the localized regeneration hypothesis, since their recovery was unaffected by colony size. However, the two larger lesion types (approximate sizes of 2 cm 2 and 3c m 2 ) confirmed the importance of large colony size for achieving fast recovery. In the second experiment we found that small lesions, repeated monthly, caused only a localized reduction in fecundity, while larger monthly repeated lesions caused significant reductions in fecundity up to a distance of 15 cm away from their site. Both experiments indicate that regeneration from injury may require an extended magnitude of energy integration throughout the colony, and that the extent of this integration is regulated by the colony in accordance with lesion characteristics. It is also concluded that in long-lived organisms such as corals, there is a priority of energy allocation to recovery rather than to reproduction. Our findings reveal the existence of injury thresholds within a colony that determine energy allocation and intra-colonial trans- location of energy products toward regions of maximal demand. We suggest that such injury thresholds may characterize many other coral species and that colony integration during stress is a basic life-preserving ability and one of the most important advantages of clonal and colonial organisms.

Tebufenozide Targeted Against Codling Moth (Lepidoptera: Tortricidae) Adults, Eggs, and Larvae

The effectiveness of tebufenozide applied against the adult, egg, and larvae of codling moth, Cydia pomonella (L.), was evaluated. Significant reductions in fecundity and egg hatch occurred after 1-h and 24-h exposures of females and 24-h exposures of males-only to residues in plastic plates. A significant reduction in egg hatch was also found after a 1-h exposure of males. The ovicidal effects of tebufenozide in field trials did not significantly differ for eggs laid on residues or treated topically. Corrected egg mortality exceeded 95% for cohorts laid <130 degree-days after sprays were applied. Fecundity and egg hatch were measured after either a 24-h exposure of moths or a 10-d exposure of moths and eggs on apple trees. Significant reductions in both fecundity and fertility occurred compared with an untreated control up to 7 d in the 24-h assays and accounted for 60-70% fewer larvae produced per mated female. The mean numbers of larvae produced per mated female after the 10-d exposure were reduced 100-75% in assays started on day 0-21 after the spray application compared with the untreated control. Fecundity was significantly reduced for 7 d and egg hatch was reduced for the entire 21-d test period in these trials. Residues had a 14-d half-life on apple foliage. Residues applied to foliage or to foliage and fruit did not significantly increase the proportion of uninjured fruit compared with the untreated control in bioassays where neonates were placed on foliage 10 cm from fruit. However, the proportion of injured fruits with shallow stings versus deep entries was higher on the treated versus the untreated plants. Field applications of tebufenozide reduced fruit injury >90% when applied early during emergence. Plots treated after the beginning of egg hatch had a larger proportion of injured fruits with shallow larval feeding.

Effects of a Mycoinsecticide on Feeding and Fecundity of the Brown Locust Locustana pardalina

The entomopathogenic fungus Metarhizium anisopliae var. acridum is being developed for use as a mycoinsecticide against locusts and grasshoppers in Africa. In addition to causing significant mortality, studies have shown the pathogen to cause reductions in feeding of a number of target species during the disease incubation period. The present study extends this work by demonstrating significant reductions in feeding following infection in another important pest species, the brown locust Locustana pardalina (Walker). Insects collected from the field following a spray application and subsequently maintained in a field laboratory showed a significant reduction in per capita feeding, as indicated by faecal production, as early as 2 days after treatment; this was before any pathogen-induced mortality. This per capita reduction in feeding by infected individuals contributed to a total reduction in feeding of 65% relative to controls. In addition to this laboratory based assessment, experiments were conducted to examine the effects of infection on mortality, feeding and fecundity in the field. Mortality rates of infected individuals in the field were significantly slower than those in the laboratory (average survival time of approximately 39 days compared with 6 days), although total mortality and percentage mycosis were equivalent. Treated individuals showed a significant reduction in body fat accumulation at sexual maturity compared with controls. This may reduce dispersal ability and total reproductive fitness. However, treated individuals exhibited a reduced pre-oviposition period resulting in them laying more eggs than untreated individuals within the first weeks following fledging. Thus, no significant reductions in fecundity were recorded by the end of the assessment period when mortality of treated individuals exceeded 90%. Given that many untreated locusts were still alive and had the potential to continue oviposition for several more weeks, however, it is likely that differences in fecundity would have become apparent if the assessment had continued. These results provide important insights for evaluating overall impacts of spray applications of the mycoinsecticide.

Effect of different combinations of MGK-264 or piperonyl butoxide with plant-derived molluscicides on snail reproduction.

Effect of sublethal treatment (20% and 60% of LC(50)/24 h) of plant-derived molluscicides, viz. Polianthes tuberosa, Trachyspermum ammi, Allium sativum powder; Azadirachta indica oil; oleoresin of Zingiber officinale; and their active molluscicidal component in combination (1:5) with MGK-264 or piperonyl butoxide on the reproduction of snail Lymnaea acuminata have been studied. It was observed that the combination of plant derived molluscicide and their active molluscicidal components, viz. tigogenin, hecogenin, azadirachtin, allicin, thymol, and [6]-gingerol combination with MGK-264 or piperonyl butoxide caused a significant reduction in fecundity, hatchability, and survival of young snails. Withdrawal of snails to fresh water after the above treatment caused a significant recovery in the fecundity of L. acuminata.

Fecundity and fertility reductions in adult leafrollers exposed to surfaces treated with the ecdysteroid agonists tebufenozide and methoxyfenozide

AbstractThe effects on the fecundity and fertility of redbanded leafroller, Argyrotaenia velutinana (Walker), and obliquebanded leafroller,Choristoneura rosaceana (Harris), exposed as adults to surfaces treated with the ecdysone agonists tebufenozide (RH‐5992) and methoxyfenozide (RH‐2485) were examined. The first part of the study consisted of recently emerged moths being exposed to treated surfaces continuously throughout their lives (including mating and oviposition). Continuous exposure to tebufenozide‐ or methoxyfenozide‐treated surfaces significantly reduced the mean number of eggs laid and the percent of eggs that hatched in both species. The second part of the study involved exposure of recently emerged virgin moths (by sex) to treated surfaces for 24 h, after which, the exposed moths were paired with a nontreated partner to mate and oviposit on nontreated surfaces. In this experiment, for A. velutinana, significant reductions in fecundity occurred only when the female was exposed to methoxyfenozide‐treated surfaces. Significant reductions in A. velutinana egg fertility occurred with both male and female exposure in the methoxyfenozide treatments and only female exposure in the tebufenozide treatments. For C. rosaceana, significant reductions in fecundity occurred with both male and female exposure in the tebufenozide and methoxyfenozide treatments. Significant reductions in C. rosaceana egg fertility occurred with both male and female exposure in the tebufenozide treatments and only with female exposure in the methoxyfenozide treatments.

Reproductive performance and longevity of female European corn borer, Ostrinia nubilalis: effects of multiple mating, delay in mating, and adult feeding

In a recent study on the pheromone-mating disruption of the European corn borer, Ostrinia nubilalis (Lepidoptera: Crambidae), we recorded a significant reduction in mating frequency, as well as a marked delay in mating in feral females captured in disruptant-treated fields. In order to be able to accurately interpret the results in terms of effective population control, the current study was undertaken on the effects of multiple matings and a delay in mating on reproductive performance. Female O. nubilalis that mated at least twice had significantly higher fecundity and fertility, compared with once-mated females. In addition, multiple-mated females deposited a significantly larger portion of their egg complement, relative to single-mated or unmated females. Females that experienced a 3-day delay in mating showed a significant reduction in fecundity compared with females that mated soon after emergence. A 1-week delay in mating resulted in a further reduction in fecundity and a near zero fertility. The effect of sugar feeding on reproduction was not significant. In general, unmated females lived longer than mated females, and sugar-fed mated females had a higher longevity than water-fed mated females.

Potential Use of In Vitro-Reared Catolaccus grandis (Hymenoptera: Pteromalidae) for Biological Control of the Boll Weevil (Coleoptera: Curculionidae)

The biological characteristics of the ectoparasitoid Catolaccus grandis (Burks) were evaluated after 1, 2, 5, and 10 generations of in vitro-rearing and compared with parasitoids reared on boll weevil, Anthonoms grandis grandis Boheman, larvae. Pupal weight of females was not significantly affected after 10 generations of in vitro-reared wasps. Fecundity of C. grandis was not significantly reduced after 5 generations of in vitro-rearing. However, the in vitro F10 showed a significant reduction in fecundity. Females reared on boll weevils had a higher pupal weight and fecundity than females reared in vitro, but in vitro-reared females exhibited significantly higher survival during the period of most intensive reproductive activity. The movement, searching capacity, and survival under field conditions of in vitro and in vivo-reared C. grandis were compared in Ricardo and Lyford, TX. Dispersal ability and searching capacity was not significantly different within a 30-m radius for parasitoid females reared by either method. However, a significantly higher proportion of stations with parasitism was recorded from in vivo-reared C. grandis. at a 60-m radius from the release point. Nevertheless, no significant difference in boll weevil mortality induced by parasitism was recorded between the 2 methods. This shows that the use of artificial diets is a promising method for mass propagating C. grandis.

Integrated mite management in apples in Israel: Augmentation of a beneficial mite and sensitivity of tetranychid and phytoseiid mites to pesticides

Augmentative releases of the phytoseiid miteTyphlodromus athiasae were evaluated during summer 1987 in an apple orchard designated to be maintained under an IPM (integrated pest management) regime. Evaluation for establishment and recovery 2 weeks after each release showed complete absence of the mite and high population density of the injurious tetranychid mites. It was suspected that pesticides that had been used to control key pests may have been the cause. Laboratory tests with the pesticides used showed that the insect growth regulators triflumuron and fenoxycarb and the fungicide triadimenol caused only slight mortality of the predacious mitesT. athiasae (0-12%) andPhytoseiulus persimilis (6–10%), but a highly significant reduction in fecundity. Four days after treatment a reduction of 94%, 74% and 100% in fecundity ofT. athiasae, and 2 days after treatment a reduction of 78%, 53% and 80% in fecundity ofP. persimilis was brought about by triflumuron, fenoxycarb and triadimenol, respectively. On the other hand, 4 days after treatment there was a 27%, 16% and 9% increase in fecundity of the phytophagous miteTetranychus cinnabarinus caused by triflumuron, fenoxycarb and triadimenol, respectively. Laboratory and field tests were carried out to evaluate 13 other pesticides as to their selectivity toT. athiasae. The compounds azinphos-methyl, penconazole, vamidothion and diflubenzuron were found to be relatively harmless to this beneficial mite and they replaced the materials mentioned above in the coming seasons in several orchards. This caused recovery in high density of the predacious mite, which allowed reduced application of acaricides and the achievement of integrated mite management.

Effects of the fungicides mancozed and dithianon on mortality and reproduction of the predatory miteAmblyseius andersoni

Laboratory studies using commercial formulations of mancozeb and dithianon at concentrations equivalent to recommended field rates of 200 and 80 g/hl, respectively, were conducted to evaluate toxic effects of these fungicides on the predatory miteAmblyseius andersoni Chant. In short-term tests where females were placed on apple-leaf disks and sprayed with mancozeb, no mortality of adults was observed; however, there was a 34% decrease in fecundity, a 7.1% decrease in egg hatch, and mortality of larvae and protonymphs was 6.7%. In long-term tests, a significant reduction in fecundity was also observed. A decrease in hatch that was dependent on age at time of treatment was found when eggs were treated directly with mancozeb. No effects on mite mortality or reproduction were observed in short-term tests with dithianon. These results suggest that dithianon might be considered as a potential alternative to mancozeb for scab control.

Influence of the Nitrogen Content in Strawberry Leaves on the Fecundity of the Vine Weevil,Otiorrhynchus SulcatusF. (Coleoptera, Curculionidae)

Abstract Detached strawberry leaves of the cultivar ‘Senga Sengana’ representing different levels of nitrogen content were fed to adult vine weevils, Otiorrhynchus sulcatus. The fecundity of the weevils was investigated in connection with their consumption and digestion of the strawberry leaves. A significant reduction in fecundity was found when the nitrogen content of strawberry leaves decreased from 2.2–2.0% N of leaf dry matter. A significant positive correlation between the weevil's fecundity and its digestion of strawbery leaves was found.

Closing of workshop

There is no need to have a workshop to show that fertility falls with age. Nothing works so well as it gets older. One has only to look at the progression of one's teeth, a very visible manifestation of the process of ageing, to make one wonder what goes on inside the reproductive system!Probably there is no evolutionary disadvantage to having reduced fertility with age because by the time that there is a significant reduction in fecundity the genetic pool which will be added to subsequent generations has already been added. In biological terms, there may be a positive advantage in reduced fertility in older women, since the human infant is dependent on its parents for such a relatively long time and there may be an advantage in the mother surviving for 7, 8, 9 or 10 years after her youngest child is born. In looking for a teleological explanation of declining fertility with age and of a menopause, this is one possible explanation.

Effects of Carbamates on House Fly Fecundity, Longevity, and Food Intake12

Topical application of sublethal but knockdown-inducing doses of Isolan® (1-isopropyl-3-methyl-5-pyrazolyl dimethylcarbamate) to house flies, Musca domestica L. resulted in substantial reduction of egg laying but did not affect mating, longevity, or egg fertility. Significant reductions in fecundity were obtained whether the insecticide was applied before or after mating and whether the insects had prior access to milk or not. Increasing the doses above the sublethal level had a greater repressing effect on fecundity but did not cause complete sterility. Thus, a sublethal dose of 0.3 μg per fly reduced total egg production by 35.8%, while doses of 0.6 and 1.0μg, representing LD10 and LD30 levels, respectively, reduced egg production by 43.1% and 77.2%, respectively. The effect of the treatments was long lasting: the daily egg production in flies treated with 0.6 μg did not equal that of the control until the 19th day after treatment; by the use of p32 milk it was found that treated flies consumed as much as 51.8% less milk than the untreated flies even 8 days after treatment. Tests with other carbamates indicated that while pliysostigniinc and Pyrolan® (3-methyl-1-phenyl-5-pyrazolyl dimethylcarbamate) had no effect on fecundity, dimetilan, carbaryl, Bayer 39007 ( o -isopropoxyphenyl methylcarbamate) and Hercules 5727 ( m -isopropylphenyl methylcarbamate) caused significant reduction in egg production. Although the precise nature of the interaction between the insecticide and the physiological processes that are significant in reproduction remains unresolved, the available evidence indicates that cholinestcrase inhibition is not directly responsible for the suppression of egg production.