Lower Number Of Eggs Research Articles

Functional activity of allatotropin and allatostatin in the pupal stage of a holometablous insect, Tribolium castaneum (Coleoptera, Tenebrionidae)

Allatotropin (AT) and allatostatin (AS) neuropeptides are known to regulate the biosynthesis of juvenile hormones (JH) in insects. Furthermore, they possess myoregulatory and other activities in a wide range of insect species. The genome of Tribolium castaneum encodes two AS and one AT precursors. Here we cloned the cDNAs of the precursors, followed their expression patterns during the pupal stage, and established their putative roles in adult development and oviposition of the females using RNA interference (RNAi). Cloning of the cDNA and gene structure analyses of the Tc-AT gene confirmed that the gene is expressed in three mRNA isoforms. Real-time PCR data demonstrate that the Tc-AT isoforms and the AS genes, Tc-AS C and Tc-AS B, are expressed in discerning developmental and tissue-specific patterns. Single injections of dsRNAi (targeted against the Tc-AT, Tc-AS C, and Tc-AS B, respectively), into young pupae resulted in abnormal adult phenotypes, whereby about half of the animals (P1 phenotype) looked relatively normal, but the females laid low numbers of eggs. The other halves (P2) exhibited strong developmental defects with abnormal duration of the pupal stage, abnormal head and body sizes, short elytra, and incomplete sclerotization. Moreover, these females deposited no eggs and died within one week after emergence. Individual silencing of the Tc-AT mRNA isoforms showed that Tc-AT3 had the most disruptive influence on adult development and fecundity of the females. Our findings clearly indicate a significant role of AT and AS neuropeptides in the pupa. The distinct mechanisms of action, however, remain to be determined.

Effects of different cruciferous crops on the fitness of Plutella xylostella (Lepidoptera: Plutellidae)

The diamondback moth, Plutella xylostella (L.), is one of the most destructive pests of cruciferous crops with a cosmopolitan distribution. The development, survival, longevity, fecundity and the life history parameters of P. xylostella were investigated on eight widely planted cruciferous crops in China, including Chinese cabbage (Brassicapekinensis Rupr; var. ‘80-7’), canola (Brassica napus L.; var. ‘Zayou 1’), cauliflower (Brassica oleracea var. botrytis, L.; var. ‘Helan 83’), Chinese radish (Raphanus sativus L.; var. ‘Xinongqingfengdong’), pakchoi (Brassica chinensis L.; var. ‘Shanghaiaikangqing’), kohlrabi (B. oleracea L. var. caulorapa DC; var. ‘Tianjingqingpielan’), cabbage (B. oleracea L. var. capitata; var. ‘Qingan 70’), and broccoli (Brassica capitata L. italicabaicai; var. ‘Zhenlü 2’). The development time from eggs to adult emergence was shortest on Chinese cabbage (15.5 days) followed by canola (15.7 days) and the longest on broccoli (22.3 days). However, pupal weight was greatest on broccoli (female: 8.1 mg and male: 6.6 mg) compared with that on the other host plants. Fecundity of P. xylostella was greatest on Chinese radish (368 eggs) followed by pakchoi (365 eggs), while the lowest number of eggs was observed on cauliflower (224 eggs). Moreover, the highest survival was recorded on canola and pakchoi (90.7% and 90.0% respectively) and the lowest on cabbage (65%). P. xylostella reared on canola had the highest intrinsic rate of increase (rm = 0.2753) and the lowest was on cabbage (rm = 0.1666). Canola was the most suitable host for P. xylostella because of shorter development period, highest survival rate and intrinsic rate of increase.

Is ICSI essential for cases with less than three MII oocytes?

ICSI is a technique of fertilization developed to treat male infertility. However, it has become routine to use ICSI in case of unexplained infertility, poor fertilization, and low egg number, despite the lack of clinical evidence to support its use. The purpose of our study was to evaluate effectiveness of ICSI vs. conventional IVF in non-male infertility couples with three or less matures. Retrospective study. All fresh, non-donor IVF cycles were performed from January 2007 through December 2012 (n=3034). This study included 146cycles with a non-male factor and less than three MII oocytes. Consequently, cycles were divided into the conventional IVF group (n=84) and ICSI group (n=62) according to the method of fertilization. In conventional IVF, each oocyte was inseminated within 4-5 hours after retrieval by adding 10,000 motile spermatozoa. We use ICSI for the patient who experienced unfertile IVF cycle or had no history of pregnancy. Outcome measures included method of fertilization, embryo quality, pregnancy rate and ongoing pregnancy rate. The differences in mean age (IVF: 34.6±2.9; ICSI: 34.3±2.9 P=0.65), basal FSH (7±1.4; 6.9±1.4 P=0.75), duration of rFSH (9.4±2.4; 9.6±2.7 P=0.62), endometrial thickness (9.7±2.0; 10.5±2.6 P=0.06) were not statistically significant. The only statistically significant differences between the IVF and ICSI groups were: history of pregnancy (61.9%; 53.2% P=0.04) and prior IVF cycle (48.4%; 38.1% P=0.03). The differences in the number of MII oocytes (2.6±0.5; 2.5±0.5 P=0.70), fertilization rate (92.3±17.4; 90.3±20.4 p=0.54), the mean number of transferred embryo (2.0±0.4; 2.0±0.6 P=0.24), pregnancy rate (51.2; 37.1 P=0.09) and on-going pregnancy rate (47.6; 35.5 P=0.74) between IVF and ICSI were not statistically significant. We found that ICSI in non-male factor infertility with three or less MII oocytes was not associated with improved fertilization rate and pregnancy rate.

Seeding experiments demonstrate poor performance of the hatching test for detecting small numbers of Schistosoma mansoni eggs in feces

Parasitological methods for the evaluation of schistosomiasis tend to be limited when parasitic burdens are low, which is a major characteristic of low intensity transmission areas. While the hatching test (HT) method has been considered to be “very sensitive”, reports of its capacity to detect low numbers of eggs remain scarce in the published literature. Our main hypothesis is that HT has limitations and cannot be recommended for diagnosing light infections or as a control of cure. Hence, this study aims to describe the performance of HT in detail, with respect to seeding experiments for egg numbers in the range of 4 to 24 eggs per gram (epg) of feces. Different numbers of eggs of Schistosoma mansoni were seeded in normal human feces. The first set of experiments evaluated the amount of feces (higher than 0.5g prevented hatching), the proximity of the light source (50cm was preferred), and the observation time required for the detection of miracidia (more than 3h did not add to sensitivity). HT was subsequently performed with 12, 10, 8, 6, 4, and 2 eggs in 0.5g of feces. The final set of experiments was performed to analyze the initial filtration step, in which surgical gauze versus a 500μm nylon mesh was compared and demonstrated losses of eggs that occurred with washing and gauze (better with nylon) sieving steps. The proposed method was found to produce 100% positivity for up to 12epg, with a sharp decrease to 33% for 8epg and less. In conclusion, HT is not recommended for diagnosing intestinal schistosomiasis in populations with light infections, considering the complexity of the procedure and its lack of effectiveness with fecal amounts higher than 0.5g even at optimized conditions.

Development of a polymerase chain reaction applicable to rapid and sensitive detection of Clonorchis sinensis eggs in human stool samples

Microscopic examination of eggs of parasitic helminths in stool samples has been the most widely used classical diagnostic method for infections, but tiny and low numbers of eggs in stool samples often hamper diagnosis of helminthic infections with classical microscopic examination. Moreover, it is also difficult to differentiate parasite eggs by the classical method, if they have similar morphological characteristics. In this study, we developed a rapid and sensitive polymerase chain reaction (PCR)-based molecular diagnostic method for detection of Clonorchis sinensis eggs in stool samples. Nine primers were designed based on the long-terminal repeat (LTR) of C. sinensis retrotransposon1 (CsRn1) gene, and seven PCR primer sets were paired. Polymerase chain reaction with each primer pair produced specific amplicons for C. sinensis, but not for other trematodes including Metagonimus yokogawai and Paragonimus westermani. Particularly, three primer sets were able to detect 10 C. sinensis eggs and were applicable to amplify specific amplicons from DNA samples purified from stool of C. sinensis-infected patients. This PCR method could be useful for diagnosis of C. sinensis infections in human stool samples with a high level of specificity and sensitivity.

Immunoprotection of mice against Schistosomiasis mansoni using solubilized membrane antigens.

BackgroundSchistosomiasis continues to be one of the most prevalent parasitic diseases in the world. Despite the existence of a highly effective antischistosome drug, the disease is spreading into new areas, and national control programs do not arrive to complete their tasks particularly in low endemic areas. The availability of a vaccine could represent an additional component to chemotherapy. Experimental vaccination studies are however necessary to identify parasite molecules that would serve as vaccine candidates. In the present work, C57BL/6 female mice were subcutaneously immunized with an n-butanol extract of the adult worm particulate membranous fraction (AWBE) and its protective effect against a S. mansoni challenge infection was evaluated.Methodology and FindingsWater-saturated n-butanol release into the aqueous phase a set of membrane-associated (glyco)proteins that are variably recognized by antibodies in schistosome-infected patients; among the previously identified AWBE antigens there is Alkaline Phosphatase (SmAP) which has been associated with resistance to the infection in mice. As compared to control, a significantly lower number of perfuse parasites was obtained in the immunized/challenged mouse group (P<0.05, t test); and consequently, a lower number of eggs and granulomas (with reduced sizes), overall decreasing pathology. Immunized mice produced high levels of sera anti-AWBE IgG recognizing antigens of ∼190-, 130-, 98-, 47-, 28-23, 14-, and 9-kDa. The ∼130-kDa band (the AP dimer) exhibited in situ SmAP activity after addition of AP substrate and the activity was not apparently inhibited by host antibodies. A preliminary proteomic analysis of the 25-, 27-, and 28-kDa bands in the immunodominant 28–23 kDa region suggested that they are composed of actin.ConclusionsImmunization with AWBE induced the production of specific antibodies to various adult worm membrane molecules (including AP) and a partial (43%) protection against a challenging S. mansoni infection by mechanism(s) that still has to be elucidated.

Effects of Chlorantraniliprole and Thiamethoxam Rice Seed Treatments on Egg Numbers and First Instar Survival of &lt;I&gt;Lissorhoptrus oryzophilus&lt;/I&gt; (Coleoptera: Curculionidae)

Effects of treatment of rice seeds with an anthranilic diamide, chlorantraniliprole, and a neonicotinoid, thiamethoxam, on egg laying and first instar survival in rice water weevil, Lissorhoptrus oryzophilus Kuschel, were examined under greenhouse conditions. Exposure of adult weevils to rice (6-7 leaf stage) grown from seeds treated with chlorantraniliprole and thiamethoxam resulted in reduction in numbers of eggs and first instars. The low egg numbers by adults exposed to chlorantraniliprole-treated plants was confirmed as a sublethal effect on adults: adult survival was not impacted after 4 d of feeding on foliage from chlorantraniliprole-treated plants but the number of eggs laid by these weevils was reduced when released on untreated plants. Furthermore, a comparison of first instar emergence from chlorantraniliprole-treated plants and from untreated plants infested with weevils previously exposed to this chemical suggested that chlorantraniliprole was also reducing egg or first instar survival. In contrast, adults that fed on foliage from thiamethoxam-treated plants showed increased mortality. Possible sublethal effects of thiamethoxam on the number of eggs laid by adults were investigated by infesting untreated plants with weevils that survived exposure to thiamethoxam via foliar feeding (7 microg active ingredient/seed). Prior exposure to thiamethoxam through adult feeding reduced egg numbers. However, potential larvicidal or ovicidal effects of thiamethoxam seed treatments could not be detected in this study because of low first instar emergence from both thiamethoxam-treated plants and from untreated plants infested with weevils previously exposed to this chemical. These experiments revealed that the two seed treatments accomplish weevil control in different ways.

Antixenosis and antibiosis of some melon (Cucumis melo) genotypes to the two-spotted spider mite (Tetranychus urticae) and a possible mechanism for resistance

SummaryThe existence of antixenotic resistance to the two-spotted spider mite [Tetranychus urticae Koch (Acari: Tetranychidae)] was investigated in 36 melon (Cucumis melo L.) genotypes using choice tests. The results revealed significant genetic diversity for this trait, and resistant (‘Dastanbu 1’, ‘’Darunghermez’, ‘Zard-Jalali’, and ‘Kharboze’) and susceptible (‘Garmsari’, ‘Zard-khareji’, ‘Bargney’, and ‘Sabz’) genotypes were identified. These four resistant and four susceptible genotypes were used in follow-up experiments in order to assess their mechanisms of antibiosis and related enzyme activities. Antibiosis data against T. urticae were collected by assessing the fecundity of mated female mites on melon leaf discs in the laboratory. The number of eggs laid by each female per day showed significant differences between genotypes. The lowest numbers of eggs were laid on ‘Darunghermez’ and ‘Dastanbu 1’, while the highest numbers of eggs were laid on ‘Garmsari’ and ‘Zard-khareji’. The activities of both peroxidase and polyphenol oxidase increased in response to infestation by T. urticae in the resistant genotypes (‘Dastanbu 1’ and ‘Darunghermez’). The resistant melon genotypes identified in this study may provide new sources of resistance against T. urticae in breeding programmes.

Effect of Beauveria bassiana, Bacillus thuringiensis, and Steinernema carpocapsa on adult wax moth Galleria mellonella (Lepidoptera: Pyralidae)

A laboratory study was conducted in the college of Agriculture, University of Baghdad to explain the impact of the pathogens, Beauveria bassiana, Bacillus thuringiensis (Agerin), and Stenernema carpocapsa ( isolated from soil ) on adult wax moth Galleria mellonella. Results showed that B.bassiana have had the heighest impact on adults (females) treatment (male treated with female treated), reached an age of 5 days when treated with 265.1×10 5 spores. The lowest number of eggs was 96/female observed with B.thuringiensis (treated male with treated female) treatment compared with other test treatments. Results also showed that the bacterium, B.thuringiensis and the nematode S. carpocapsa caused the highest impact than fungal treatment on the second generation ,with an average of female age of (0.0) days and a 100 percentage of no hatching for both treatments (male treated with female treated).

Condensed tannins from Sesbania sesban and Desmodium intortum as a means of Haemonchus contortus control in goats

Two experiments were conducted to determine whether the proanthocyanidin (condensed tannin)-containing forage legumes Desmodium intortum cv Greenleaf and Sesbania sesban (accession 15019) could be integrated into a feeding management strategy as a means of Haemonchus contortus control in goats. The anthelmintic effects of condensed tannin extracts from the two legumes on H. contortus L(3) larvae were studied in an in vitro larval migration inhibition system. The extracts inhibited larval migration in a dose-dependent manner, and at concentrations from 1,000 μg/ml condensed tannin, the extract from D. intortum caused a significantly higher inhibition of larval migration than did the corresponding concentrations of the S. sesban extract (P < 0.01). Prolonged feeding of tanniniferous forage legumes showed that animals receiving D. intortum had the lowest total worm burden, the lowest female to male parasite ratio, the lowest number of eggs in the uterus of each female worm and the lowest per capita fecundity (P < 0.01). However, there was no change in the performance (weight gain) of parasite-infected goats probably due to incomplete removal of the parasite or prolonged confinement of goats in small pens, which calls for further investigation. However, since there is no single efficient method in control of parasites, based on the obtained data from this experiment, integrated feeding of D. intortum with other suitable method of parasite control is thus suggested.

Genetic control of resistance to Meloidogyne incognita race 1 in the Brazilian common bean (Phaseolus vulgaris L.) cv. Aporé

The use of resistant cultivars is one of the best methods for nematode control and reduction of economic losses caused by these pathogens. Studies of inheritance of nematode resistance in common bean (Phaseolus vulgaris L.) are nonetheless scarce. The present paper reports on the estimation of genetic parameters associated with resistance to the root nematode Meloidogyne incognita race 1 in common beans. Two contrasting bean lines, ‘Apore’ (P1 = nematode resistant) e ‘Macarrao Rasteiro Conquista’ (P2 = susceptible), and the generations F1 (P1 × P2), F2 (P1 × P2), BC1(P1) = (F1 × P1) and BC1(P2) = (F1 × P2), were assessed 45 days after nematode inoculation, through a scale related to the number of eggs per gram of root tissue. Dominant genetic effects were inferior in magnitude to additive effects, indicating incomplete dominance of nematode resistance. Dominance was in the direction of increased nematode resistance (i.e., lower number of eggs per g root). Resistance to Meloidogyne incognita race 1 in common bean is under control of a single gene locus, with incomplete dominance of the resistance allele present in ‘Apore’, but modifier genes affecting its expression appear to be present in the susceptible parent ‘Macarrao Rasteiro Conquista’.

Reproductive performance and natural antagonists of univoltine population of Ips typographus (Coleoptera, Curculionidae, Scolytinae) at epidemic level: a study from Šumava Mountains, Central Europe

Population ofI. typographuswas studied in one locality with small-scale and short-term outbreak distant from large-scale and long-term outbreak area by several hundred meters. In total, ten spruce trees infested by the spruce bark beetle were examined. Always four stripes of bark (sample area) with the length equal to half the circumference of the trunk and the width of approximately 0.5 m were analyzed. The local spruce bark beetle population was characterized by high population density (1.5±1.2 entry holes per dm2), low number of eggs per female, and short maternal galleries. Relatively low reproductive success (0.8 female offspring per one mother beetle, percentage of surviving individuals varies between 1and 18 % was documented. The parasitism rate of living developmental stages of spruce bark beetle by larval parasitoids averaged 14 %. The level of infestation by pathogens and endoparasitoids in maternal beetles from their galleries was low. Highly likely, it is a result of short-term outbreak during which response of parasitoids was delayed in time.

Life history parameters of Thrips tabaci (Thysanoptera: Thripidae) on six commercial cultivars of canola

The onion thrips, Thrips tabaci Lind. (Thysanoptera: Thripidae), is an important pest of the canola crop, Brassica napus L., in the Ardabil region. In this study, life history parameters of T. tabaci were investigated on six canola cultivars, namely: Talayh, Zarfam, RGS003, Opera, Option500, and Hayola401. Experiments were performed in a climate chamber set at 25 ± 1°C and 55 ± 5% RH under 16L:8D. The results indicated that the development time of immature stages was significantly longer on RGS003 than on Opera, Hyola401, Zarfam, Option500, and Talayh. The onion thrips reared on RGS003 had the lowest number of eggs laid per female (15.5) and the lowest survival rate (40%) among the tested cultivars. The lowest intrinsic rate of natural increase (rm) and population growth rate (λ) were observed on RGS003, and were the highest on Zarfam. The generation time (T) was shortest on Zarfam (21.5 days) and longest on RGS003 (26.5 days). Similarly, the doubling time (DT) was shortest on Zarfam (4.5 days) and longest on RGS003 (8.1 days). Considering the significant effect of the host plant on the life history parameters of onion thrips, it was concluded that RGS003 is the least suitable cultivar among the other tested canola cultivars for integrated management of onion thrips in canola fields.

Should ICSI be recommended routinely in patients with four or fewer oocytes retrieved?

To determine if patients with a low response to controlled ovarian hyperstimulation during IVF benefit from intracytoplasmic sperm injection (ICSI) METHODS: Retrospective analysis of 350 IVF cycles in which four or fewer oocytes were retrieved. Severe male factor cases were excluded from analysis. Conventional insemination (CI) and ICSI were compared, with primary outcome measures of fertilization rate, implantation rate, clinical pregnancy rate per embryo transfer, and pregnancy loss rate. Fertilization rates per oocyte retrieved for CI and ICSI were comparable (51.5% vs. 51.8%). Parallel implantation rates (22% vs. 25%), clinical pregnancy rates (32.8% vs. 33.3%), and loss rates (26.7% vs. 39.5%) were also noted. No difference in cancelled cycles was reported. Our results demonstrate that in the presence of normal semen parameters, low egg number is not an indication to perform ICSI.

Impact of the photosensitizers hematoporphyrin coated gold nanoparticles on biomphalaria alexandrina snails

The present study was done using two concentrations of the photosensitizer Hematoporphyrin coated Gold Nanoparticles (HpdGNP3) (5x10–6 , 5x10–5 mole/dicemeter–3), to evaluate their efficacy on survival rate, egg-laying capacity of Biomphalaria alexandrina snails and on histological deteriorations in their hermaphrodite gland. B. alexandrina snails were incubated for 12 hours at each tested concentration in the dark, thereafter they were exposed to direct sunlight (336.2 W/m2) for either 2 or 4 hours followed by 24 hours of recovery. Control snails were treated with these concentrations without exposure to light irradiance. Another experiment was carried out simultaneously and the snails were left for 4 weeks of recovery to evaluate their egg-laying capacity (Mx). The results indicate that 5x10–5 Mdm–3 (HpdGNPs) with 4 hours of exposure sunlight suppressed the survival rate of B. alexandrina snails by 50%. Meanwhile, control snails incubated with 5x10–5 Mdm–3 HpdGNPs were not affected and still alive (100%). For snail’s fecundity (Mx), treated snails laid low number of eggs throughout the recov-ery period (4 weeks), in comparison with that of control ones. The highest value of Mx for snails treated with 5x10–5 Mdm–3 Hpd coated GNPs was recorded at the 3rd week of recovery period, being 6.7 eggs/snail, compared to 37.6 eggs/control snail. This has a negative reflect on the reproductive rate (Ro) of treated snails as it was reduced under these conditions by 76.6% and 86.1%, respectively.Histological tests re-vealed injuries in spermatocytes, oocytes, several degenerations of B.alexandrina hermaphrodite gland then evacuations in many gonad’s cells which severely suppressed their capacity for egg-laying. It is concluded from the present work that exposing B. alexandrina snails to sublethal concentrations of the photosensiter Hpd coated GNPs (12 hours incubation, 4 hours exposure to 336.2 W/m2) significantly reduced their reproductive capacity that may have a negative reflect on schistosomiasis transmis-sion.

Efeito da qualidade da água no ciclo de vida e na atração para oviposição de Aedes aegypti (L.) (Diptera: Culicidae)

The present research aimed at evaluating the influence of the water quality in the life cycle and attraction of Aedes aegypti (L.) females to oviposit using different sources of water (raw sewage, effluent of UASB reactor, effluent of polishing lagoon, effluent of anaerobic filter, rain water and de-chlorinated water). The immature development time and survivorship were evaluated on a daily basis in two distinct feeding systems (with and without food). The quality of the water was shown to affect the egg and larval stages, but not the pupal or the adult. In the absence of food, no development was observed in rain water and de-chlorinated water. Immature development was faster in water sources from raw sewage, although with the lowest survivorship (37.3%). Free-choice tests indicated that females preferred to lay most of their eggs on water collected from the effluent of a UASB reactor, achieving the highest oviposition activity index (OAI) of 0.57. In non-choice tests, females laid larger batches of eggs in water collected from anaerobic filters (204.8 eggs), with the lowest number of eggs being laid on de-chlorinated water (37.3 eggs). It can be concluded that A. aegypti does not demonstrate any particular preference to lay eggs on clean water. This has serious implications for developing strategies to manage populations of this important vector in urban areas as it was shown to lay eggs and successfully develop on several different sources of water.

Influence of egg storage time and preincubation warming profile on embryonic development, hatchability, and chick quality

When eggs are stored beyond 7 d, hatchability and chick quality decrease. The cause of the negative effects of prolonged egg storage is not clear. The negative effects may be caused by a decrease in embryo viability due to an increase in cell death. The optimal time and curve of preincubation warming (the preincubation warming profile) may be different for eggs stored over short and long periods of time because embryo viability is dependent on egg storage time. The aim of this study was to investigate whether preincubation warming profiles affect embryonic development, hatchability, and chick quality when eggs are stored for a short or prolonged time. Two experiments were conducted. In both experiments, a 2x2 completely randomized design was used with 2 storage times (4 and 14 d at 17 degrees C in experiment I and 4 and 13 d at 19 degrees C in experiment II) and 2 preincubation warming profiles (within 4 or 24 h from storage temperature to 37.8 degrees C). In experiment I, results suggested that the effect of preincubation warming profile on hatchability was dependent on storage time. However, because a low number of eggs were used in this experiment, these differences were not significant. In experiment II, the interaction between storage time and preincubation warming profile was observed for embryonic mortality during the first 2 d of incubation and hatchability (P=0.006 and P=0.01, respectively). When storage time was 13 d, embryonic mortality during the first 2 d of incubation decreased by 4.4% and hatchability increased by 5.7% when the 24-h preincubation warming profile was used instead of the 4-h preincubation warming profile. However, no effect of preincubation warming profile was observed when storage time was 4 d. In both experiments, chick quality decreased when storage time increased but was not affected by preincubation warming profile. We concluded that a slow preincubation warming profile is beneficial for hatchability when storage time is prolonged but does not affect chick quality.

Egg numbers and fecundity traits in nine species of &lt;i&gt;Mantella&lt;/i&gt; poison frogs from arid grasslands and rainforests of Madagascar (Anura: Mantellidae)

The body size and number of eggs in dissected females were analysed in nine species of the Malagasy frog genus Mantella basing upon preserved specimens. These species were distinguished in terms of habitat and grouped as ‘grassland species’ (included M. betsileo, M. expectata, M. viridis), and ‘rainforest species’ (M. baroni, M. crocea, M. cowani, M. laevigata, M. nigricans, M. pulchra). The species with the lowest egg - number was M. cowani with a mean egg number of 37 ± 15, while the species with the highest egg-number was M. viridis with 115 ± 21 eggs. In general, the grassland species are characterised by a higher number of relatively small eggs. Moreover, their fecundity was positively and significantly correlated to female body size. Rainforest species were smaller in size and with a lower number of eggs. We interpreted these differences as possible consequences of habitat adaptations. Among the studied species, the Critically Endangered Mantella cowani is also featured by a low number and large size of eggs. This is likely correlated with the high elevation site of the central highlands where this species occurs.

Recovery threshold of Toxocara canis eggs from soil

The purpose of this study was to evaluate the threshold of Toxocara canis eggs form soil samples through utilisation of a centrifuge-flotation technique (CFT). Aliquots of soil (1 g each) were artificially contaminated with known numbers of T. canis eggs (1, 10, 25, 50, 100, and 200 eggs). The threshold was evaluated based on a CFT using zinc sulphate (Zn 2SO 4) and sodium nitrate (Na 2NO 3) solutions at a specific gravity of 1.20. The number of eggs recovered was directly proportional to the number of eggs employed to seed the soil. Both solutions enabled full recovery of samples containing merely three eggs; only Zn 2SO 4 demonstrated efficiency in soil contaminated with a single egg. A recovery rate of 100% was obtained for all tests with samples containing 10 and 25 eggs for Zn 2SO 4 and Na 2NO 3, respectively . There was no difference in the mean number of recovered eggs regarding either the efficacy of the solutions or the repetition of evaluations in the same trial ( p > 0.05). Therefore, the CFT is efficient for the detection of Toxocara eggs, even in samples containing low egg numbers.

STUDIES ON NEEM SEED KERNEL EXTRACTS AS OVIPOSITION DETERRENTS AND OVICIDAL COMPOUNDS FOR THE COTTON LEAF WORM MOTHS, Spodoptera littoralis (Boisd.)

Mated female moth of the cotton leafworm, S. littoralis laid a total number of 1564.22 eggs during its whole life. In a free choice test, treating N. oleander leaves (as an oviposition site) with an aqueous extracts of neem seed kernel solutions extracted by different organic solvents reduced the number of deposited eggs on it. The lowest number of eggs was recorded when methanol was used for extraction, followed by chloroform, and the highest was, however, obtained after using benzene, butanol and ethyl acetate. The number of deposited eggs decreased as the concentration of any tested neem extract increased to reach the minimum at 0.2%. This means that the most deterred neem seed kernel extract is that which extracted with methanol at the concentration of 0.2%.Hatchability percentage of S. littoralis eggs greatly affected by the type of organic solvents used for neem extraction and the concentration of each extract on treated N. oleander leaves. The lowest hatchability was recorded after using methanol, followed by chloroform.On the other hand, an increase in neem seed kernel extract concentration caused an obvious decrease in egg hatchability.