Reduction In Hatchability Research Articles

Benzyl isothiocyanate affects development, hatching and reproduction of the soybean cyst nematode Heterodera glycines

Benzyl isothiocyanate (BITC), prepared in 1% methanol and applied at micro-molar doses, decreased Heterodera glycines infective second-stage juvenile (J2) movement, hatching and reproduction on soybean, Glycine max. Direct exposure of J2 to 30 μM BITC caused an immediate decrease (17%) in J2 movement relative to 1% methanol controls, and within 3 h exposure eliminated >99% of movement. Continuous exposure of H. glycines eggs to 30 μM or 60 μM BITC significantly decreased percentage hatch of J2 measured at 7 days (30 μM, 15.8 ± 2.4%; 60 μM, 7.9 ± 2.2%) relative to controls (44.9 ± 4.1%). Control percentage hatch increased between days 7 and 14 (87.5 ± 2.3%), whereas there was no significant increase in hatch after Day 7 in either treatment group. The effect of BITC on hatch was rapid and persistent. Following 4 h exposure of eggs to either 30 μM or 60 μM BITC and transfer to water, percentage hatch at Day 14 was 51.3 ± 6.3% and 15.6 ± 1.4%, respectively. Each value was significantly less than the control percentage hatch (96.5 ± 0.2%). The same treatment method also resulted in decreased reproduction. The mean number of cysts per plant harvested 5 weeks after inoculation with control eggs (173.0 ± 12.1) was significantly greater than the numbers from plants inoculated with either 30 μM (78.9 ± 8.2) or 60 μM (38.3 ± 4.5) BITC treated eggs. Reduction of hatch and reproduction were strongly correlated, with for both 30 μM or 60 μM BITC treatments. The effects of BITC were primarily on the early embryo. The percent of all embryos in the multicellular stage at Day 14 in control eggs was 4.9 ± 0.7%, but increased to 35.1 ± 4.3% (30 μM) and 56.3 ± 4.5% (60 μM) in BITC treated eggs. BITC has multiple effects on H. glycines, affecting both infective juvenile movement and embryonic development, and decreasing reproduction.

Evaluation of the Effect of Water Soluble Fraction (Wsf) of Bonny Light Crude Oil and Sublethal Concentrations of <em>Lepidagathis alopecuroides</em> (Vahl) on Reproduction in Clarias gariepinus (Burchell 1822)

The aim of this study was to evaluate the effect of crude oil Water Soluble Fraction (wsf) and the aqueous extract of <em>Lepidagathis alopecuroides</em> on fertilty and hatchability of <em>Clarias gariepinus</em>. Artificially fertilized eggs of <em>Clarias gariepinus</em> were exposed to five sublethal concentrations of <em>L. alopecuroides</em> and five concentrations of the water soluble fractions of crude oil. The results showed that there was concentration dependent reduction in hatchability of eggs exposed to <em>L. alopecuroides</em>. A highly significant (p<0.01) but negative linear correlation (r = -0.9327) was observed between percent hatchability and the concentration of crude oil water soluble fraction. Both relationships were linear with regression equations y = -73.68x+65.92 vs. y = -0.085x+75.03 and coefficient of determination (R²) = 0.870 vs. 0.915, respectively. This result confirms that both <em>L. alopecuroides</em> and crude oil water soluble fraction are capable of inhibiting hatchability of <em>Clarias gariepinus</em> and reducing the reproductive capacity of this species in the wild.

Breeding synchronization facilitates extrapair mating for inbreeding avoidance

Extrapair (EP) mating can enable females to reduce the negative effects of inbreeding. However, opportunities for EP mating are often ecologically or demographically constrained, and it is unclear whether and how females can overcome these constraints. Here, we show that fitness costs from inbreeding in purple-crowned fairy-wrens (Malurus coronatus) are severe (≥30% reduction in hatchability of eggs in incestuous pairs). Although EP paternity was low for unrelated pairs (3% of broods), and negatively affected by low breeding density, 46% of broods produced by incestuously paired females contained EP young that were almost always sired by a direct neighbor. Moreover, females in incestuous pairs initiated egg laying more synchronously with direct neighbors than females in an unrelated pair, and more synchronous broods were more likely to contain EP young. Because male sperm stores are highest around their own partner’s fertile period, our results imply that incestuously paired females achieve high levels of EP paternity by adjusting the timing of egg laying to match peak fertility of neighboring males. This example of a dramatic increase in EP paternity due to subtle behavioral adjustments illustrates that negative effects of inbreeding exert strong selection for female strategies to facilitate EP mating, and this may contribute to unexplained variation in EP paternity.

Effects of macrocyclic lactones on the reproductive parameters of engorged Rhipicephalus (Boophilus) microplus females detached from experimentally infested cattle

The present study therefore assessed the deleterious effects of MLs (ivermectin, abamectin, doramectin and moxidectin) on the reproductive parameters of engorged Rhipicephalus (Boophilus) microplus females that naturally detached from experimentally infested cattle in two experiments. The following reproductive parameters of engorged female ticks were analyzed: female weight, egg mass weight, percentage of hatchability, percentage of reduction in oviposition, percentage of reduction in hatchability, reproductive efficiency and percent control/efficacy of formulations with respect to reproductive parameters. In the experiment I, statistical analysis of the data grouped into 5-days intervals revealed that pour-on application of abamectin (500mcg/kg) had significantly (p⩽0.05) reduced engorged female weight, egg mass weight and percent hatchability on days 6–15, 6–20 and 11–20 post-treatment (p. t.) compared to the respective data for detached and pre-selected engorged females in the control group. The abamectin, demonstrated 33.41% of reduction in oviposition, 6.77% in hatchability and abamectin efficacy was of 13.99%. In the experiment II, statistically significant reductions (p⩾0.05) were observed in animals treated subcutaneous with ivermectin (630mcg/kg), doramectin (700mcg/kg) and moxidectin (1000mcg/kg) relative to the control for days 6–40, 6–48 and 6–40 p. t., respectively. Ivermectin reduced hatchability only on days 16–20 p. t., whereas doramectin significantly reduced (p⩽0.05) hatchability on days 6–10 and 16–35 p. t. For moxidectin, deleterious effects on hatchability were observed on days 16–35 p. t. The percent reductions in oviposition of engorged female ticks were 46.31%, 62.17% and 61.02% with ivermectin, doramectin and moxidectin treatments, respectively. The percent efficacy of the formulations on the reproductive parameters of engorged female ticks was 21.22% for ivermectin, 36.03% for doramectin and 35.45% for moxidectin. Among the MLs assessed, doramectin and moxidectin had the highest acaricidal efficacies and the most deleterious effects on the reproductive parameters of engorged R. (B.) microplus females. However, future studies will be necessary to assess the extent to which these effects, along with acaricidal activity, can be used to control the ectoparasite in cattle.

Effects of catechins and low temperature on embryonic development and hatching in Heterodera glycines and Meloidogyne incognita

Mimics of two natural influences, a chemical similar to one present in cyst nematodes and low temperature exposure of nematode eggs, were evaluated for their effects on quantitative and qualitative features of embryonic development and hatching. The polyphenol epigallocatechin gallate (EGCG), an analogue of a compound found in nematode cysts, reduced hatch from both Heterodera glycines and Meloidogyne incognita eggs. Reduction was by 22.7% in H. glycines and 68.5% in M. incognita at 14 days after exposure to 1.0 mM EGCG. Significant reductions in hatch were observed at 7 days after exposure in H. glycines eggs, and as early as 5 days in M. incognita. Half-maximal percentage hatch was delayed by 0.6 days in H. glycines and 1.1 days in M. incognita (16.2 and 18.3%, respectively). Decreased hatch was associated primarily with an increase in unhatched, but viable, second-stage juveniles (J2). Hatch levels could be completely restored by day 14 in both species if EGCG was replaced with water on day 3. Replacement on day 7 partially restored hatch in M. incognita but was not effective in H. glycines. Inhibition of chitinase activity by EGCG suggests one factor in J2 retention in the egg. Exposure to low temperature decreased hatch by ca 50% in both species but without accumulation of unhatched J2. This stage peaked on day 3 in H. glycines-treated eggs, and on day 7 in M. incognita. However, response to low temperature in each species was characterised by developmental arrest at the first-stage juvenile.

Effects of cyst components and low temperature exposure of Heterodera glycines eggs on juvenile hatching in vitro

AbstractThe effects of low temperature treatment of Heterodera glycines eggs and the interaction of this treatment with egg condition and cyst influences were examined in vitro. Exposure of eggs to 5°C for 1 week followed by a return to normal culture temperature resulted in a 25-33% reduction in hatch after 2 weeks at 28°C but there was no effect on the timing of hatch. Hatch from encysted eggs was 40% lower than from free eggs at 2 weeks, and hatch from low temperature-encysted eggs was more than 60% lower during the same period. Encystment also altered the timing of hatch relative to free eggs from the same cohort. Hatch from free eggs in the presence of cyst contents was accelerated relative to free eggs without cyst contents, but the total cumulative percent hatch was not increased. Reduction in hatch as a result of low temperature treatment was significant only if the treatment was applied prior to the first juvenile stage (J1). J1 were not affected relative to the hatch of second-stage juveniles (J2). However, the effect of low temperature on earlier stages was not detected until development ceased at early J1 and later J1. Also, low temperature treatment affected the apparent locomotion of some newly hatched J2; 16-fold more J2 from treated eggs were retained on 30 μm pore sieves than those from control eggs. The depression of hatch by low temperature egg treatment was apparently the result of the residual effects on early embryo stages, leading to arrest of development prior to J2.

Irradiation of Anastrepha ludens (Diptera: Tephritidae) eggs for the rearing of the fruit fly parasitoids, Fopius arisanus and Diachasmimorpha longicaudata (Hymenoptera: Braconidae)

Irradiated eggs of Anastrepha ludens were evaluated as hosts of two fruit-fly parasitoids for mass rearing. Three different ages of A. ludens eggs (24-, 48- and 72-h-old) were analyzed for hatchability after being subjected to radiation doses of 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5 and 30 Gy. No significant reduction in hatchability occurred with the 72-h-old eggs at any of the radiation dose levels and no adult emergence occurred at radiation doses greater than 25 Gy. Seventy two-h-old eggs irradiated above 25 Gy were found to be the best age and dose for fruit fly egg hosts to be used in mass rearing the egg parasitoid Fopius arisanus. It was demonstrated that larvae hatching from the irradiated A. ludens eggs can also be used as hosts for Diachasmimorpha longicaudata. Parasitoid emergence of both species was not statistically different from the control group (parasitoids emerged from non-irradiated host). The fecundity of parasitoids emerged from irradiated hosts also was similar to that obtained with parasitoids reared with non-irradiated hosts. There were some statistical differences between the curves for longevity. However, these were not clearly correlated with radiation dose. The results of this study will aid in the design of improved methods for mass rearing and release of fruit-fly parasitoids.

Multigeneration assessment of nonylphenol and endosulfan using a model Australian freshwater fish, Melanotaenia fluviatilis

Changes over two generations in offspring and reproductive ability were recorded in crimson-spotted rainbowfish (Melanotaenia fluviatilis), a model Australasian freshwater fish, following a 24 h exposure to nominal nonylphenol concentrations of 50, 100, 500, 1000, 2250, and 5000 microg/L and following a 4 h exposure to nominal endosulfan concentrations of 1.0, 5.0, 10, 22, 33, and 50 microg/L. There were also four replicated control treatments: control 1 and 2 and solvent control 1 and 2, as well as "positive" female and male controls: 1 microg/L estradiol 1 and 2 and 1 microg/L testosterone 1 and 2. Results suggested that there may be some parental transfer of toxicants to embryos even over this short exposure period. Fertility of M. fluviatilis was reduced by a 24 h pulse exposure of adults to 100 microg/L nonylphenol and a 4 h exposure to 1.0 microg/L endosulfan. Hatch rates were significantly reduced after exposure to nonylphenol, endosulfan, and estradiol control but not in solvent controls and testosterone control. Significant correlations were found between reproductive and physiological parameters for nonylphenol and endosulfan exposed F0 adult rainbowfish. The major reproductive effects were on hatchability of the F1 generation and the gonadosomatic indices of male F1. The respective nominal NOEC and LOEC's for nonylphenol were 50 and 100 microg/L, and for endosulfan were <1.0 and 1 microg/L. These observed effects have the potential to significantly impact exposed rainbowfish populations through the observed approximately 45% reduction of hatchability and thus larval production.

Moisture during Egg Incubation Adversely Affects Hatching of the West Indian Sweetpotato Weevil, Euscepes postfasciatus (Coleoptera: Curculionidae), When the Eggs are Incubated En Masse

We compared the egg-hatching of Euscepes postfasciatus (Fairmaire) with and without moisture treatment to test whether moisture is necessary during egg incubation when a large number of eggs are gathered into a mass. Moisture treatment exhibited significant undesirable effects on hatching (reduction of hatchability, delay of hatching, and increase of the variance of hatching date) compared to no moisture treatment. In addition, moisture treatment significantly increased the incidence of fungus on the egg surface, which can subsequently contaminate the larval artificial diet. Based on these results, we concluded that moisture is not necessary for incubating E. postfasciatus eggs. Two possible explanations for the undesirable effects of moisture on hatching were discussed: a direct effect by preventing respiration of the eggs and an indirect effect through fungal infection of the eggs.

Maternal dietary conjugated linoleic acid alters hepatic triacylglycerol and tissue fatty acids in hatched chicks

The effects of feeding CLA to hens on newly hatched chick hepatic and carcass lipid content, liver TAG accumulation, and FA incorporation in chick tissues such as liver, heart, brain, and adipose were studied. These tissues were selected owing to their respective roles in lipid assimilation (liver), as a major oxidation site (heart), as a site enriched with long-chain polyunsaturates for function (brain), and as a storage depot (adipose). Eggs with no, low, or high levels of CLA were produced by feeding hens a corn-soybean meal-basal diet containing 3% (w/w) corn oil (Control), 2.5% corn oil + 0.5% CLA oil (CLA1), or 2% corn oil + 1.0% CLA oil (CLA2). The egg yolk content of total CLA was 0.0, 1.0, and 2.6% for Control, CLA1, and CLA2, respectively (P< 0.05). Maternal dietary CLA resulted in a decrease in chick carcass total fat (P < 0.05). Liver tissue of CLA2 chicks had the lowest fat content (P < 0.05). The liver TAG content was 8.2, 5.8, and 5.1 mg/g for Control, CLA1, and CLA2 chicks, respectively(P < 0.05). The chicks hatched from CLA1 and CLA2 incorporated higher levels of cis-9,trans-11 CLA in the liver, plasma, adipose, and brain than Control (P< 0.05). The content of 18:0 was higher in the liver, plasma, adipose, and brain of CLA1 and CLA2 than Control (P< 0.05), but no difference was observed in the 18:0 content of heart tissue. A significant reduction in 18:1 was observed in the liver, plasma, adipose, heart, and brain of CLA1 and CLA2 chicks (P< 0.05). DHA (22:6n-3) was reduced in the heart and brain of CLA1 and CLA2 chicks (P < 0.05). No difference was observed in carcass weight, dry matter, or ash content of chicks (P> 0.05). The hatchabilities of fertile eggs were 78, 34, and 38% for Control, CLA1, and CLA2, respectively (P< 0.05). The early dead chicks were higher in CLA1 and CLA2 than Control (18 and 32% compared with 9% for Control), and alive but not hatched chicks were 15 and 19% for CLAl and CLA2, compared with 8% for Control (P < 0.05). Maternal supplementation with CLA leads to a reduction in hatchability, liver TAG, and carcass total fat in newly hatched chicks.

In ovo temperature manipulation influences post-hatch muscle growth in the turkey

1. The effect of manipulating egg incubation temperature for short periods on turkey muscle development was determined using the M. semitendinosus, a thigh muscle, as the model. 2. Experiment 1. Eggs were incubated at a control temperature of 37·5°C. For a 4-d period of 0 to 4, 5 to 8, 9 to 12, 13 to 16, 17 to 20 or 21 to 24 embryonic days (ED) eggs were transferred to either 38·5 or 35·5°C. A regime of 38·5°C at 5 to 8 and 9 to 12 ED caused an increased myonuclei number and muscle fibre number, respectively. 3. Experiment 2. Eggs were incubated at a control temperature of 37·5°C. At 5 to 8 ED eggs were transferred to 38·5 or 35·5°C. Temperature-manipulated embryos showed a delay in differentiation (myogenin expression) of the semitendinosus muscle compared to controls. 4. Manipulating the incubation temperature for 4 d in early incubation alters muscle development in the turkey with no observation of deformities or reduction in hatchability. We speculate that this increase in temperature may result in an improved muscle growth in the post-hatch bird.

Vertical transmission of nucleopolyhedrovirus in the silkworm, Bombyx mori L

Nucleopolyhedrovirus (NPV) was tested for vertical transmission in the silkworm, Bombyx mori. Fifth instar larvae were exposed to four different dosages of BmNPV (830, 1300, 1800, and 2000 OBs/larva) and a dosage of about 2000 OBs/larva was found suitable for obtaining infected adults. Histopathological studies revealed the infection in susceptible tissues and organs initially, and at later stages of infection cycles the spermatocytes and nurse cells in the young oocytes were infected in the larval rudiments of testis and ovary, respectively. The mating of infected females with uninfected males resulted in significant reduction in fecundity ( P<0.01) and hatching of eggs ( P<0.001) due to transovarial transmission of BmNPV. Mating tests of uninfected females and infected males also confirmed venereal transmission as there was a significant reduction in hatching of eggs ( P<0.01). Further, among the F 1 hybrid offspring (infected female × uninfected male) that were infected transovarially, larval progeny died at first and second instar stages, whereas those infected venereally developed acute lethal infection late and died by the end of third and fourth instar stage. PCR amplification and sequencing of 473 bp of immediate early-1 ( ie-1) gene of BmNPV isolated from the viral-infected parent and the F 1 offspring confirmed that the viral infection is vertically transmitted to the progeny.

Cocaine and salicylate: documentation of hydroxyl radical formation in hearts and brains of 18-day-old chick embryos and unexpected interactive toxicity.

Multiple low doses of cocaine (COC) may cause intermittent vasoconstriction and reperfusion, leading to elevations in damaging reactive oxygen species, such as hydroxyl free radicals (*OH). Salicylate may offer protection because it reacts with *OH and/or because of its anti-inflammatory actions. To measure *OH concentrations in hearts and brains of chicken embryos exposed to multiple, small doses of COC, and to determine if otherwise non-toxic doses of sodium salicylate (NaSal) protected against the marginal but significant reduction in hatchability caused by a model of "binge" COC exposure. Three experiments were carried out. In the first, 67.5 mg COC/kg egg was administered as five doses of 13.5 mg/kg egg or 0.675 mg/egg every 1.5 h, injected just beneath the shell, on day 18 of development (E18), 1 h after NaSal (25 or 100 mg/kg egg) was injected as a bolus. Hearts and brains taken shortly afterward were analyzed for *OH. In experiment 2, the dose of COC was reduced to 56.5 mg/kg egg so as to achieve a small but significant reduction in hatchability in order to determine if NaSal protected against or enhanced COC's toxicity, manifest as an increase or decrease in hatchability. The doses of NaSal for this experiment were 50, 100 or 200 mg/kg egg, all devoid of effects upon hatchability when injected alone. Experiment 3 was done to confirm the presence of vascular disruptions/hemorrhages observed on COC-exposed embryos while harvesting hearts and brains for chemical analyses and to quantify what appeared to be enhanced COC-related vascular accidents associated with NaSal pretreatment. The dose of NaSal used in experiment 3 was 200 mg/kg egg and COC was injected again at 5x13.5 mg/kg egg. COC increased *OH in hearts and brains of chicken embryos on E18, and non-toxic doses of NaSal (i.e. 100 or 200 mg/kg egg) enhanced COC's toxicity in a dose-related manner. The lowest NaSal dose (50 mg/kg egg) may have offered some protection against the effects of COC, as the reduction in hatchability caused by 56.5 mg COC/kg egg was no longer significant. Vascular disruptions/hemorrhages were associated with and most likely responsible for the interactive toxicity. Our unexpected findings may be of clinical relevance because of the use of aspirin for treatment of misdiagnosed "preeclamptic" COC-abusing pregnant women and its possible use for COC abusers at risk for reduced cerebral blood flow and stroke.

Interaction of treatment of both adult and immature Coleoptera with a chitin synthesis inhibitor affects mortality and development time of their progeny

AbstractChitin synthesis inhibitors, like many other insect growth regulating insecticides, do not kill adult insects but cause mortality of the immature stages. Pre‐exposure of adult stored grain Coleoptera, Rhyzopertha dominica (F.) (Bostrichidae) and Sitophilus oryzae (L.) (Curculionidae) and development of their progeny in grain treated with the chitin synthesis inhibitor, chlorfluazuron, influenced the mortality and development rate of the progeny. Hatch rate of eggs from R. dominica adults that had both developed and laid on wheat treated with 0.75 mg kg−1 chlorfluazuron was reduced by almost 50% compared with untreated eggs, with an LC50 of 0.84 mg kg−1. Eggs laid on treated wheat by R. dominica adults that had been exposed only to treated wheat for 2 weeks before oviposition showed greater reduction in hatch: 75% reduction of normal hatch rate at 0.25 mg kg−1 and almost 100% reduction at 2 mg kg−1 chlorfluazuron, with an LC50 of 0.19 mg kg−1 chlorfluazuron. X‐rays were used to monitor the development and mortality of the immature stages of S. oryzae that developed within the wheat grains. Numbers of eggs laid were not affected by chlorfluazuron treatment. The combination of pre‐exposure of adults and chlorfluazuron concentration had an additive effect on mortality of immature S. oryzae. Pre‐exposure of adults caused most mortality in the first three weeks of development (eggs and larvae), whereas development in treated wheat caused mortality from weeks 3 to 8 (pupae and adults); higher concentrations of chlorfluazuron caused higher mortality. Development in wheat treated with 1 mg kg−1 chlorfluazuron caused 12% corrected overall mortality of progeny while pre‐exposure to the same concentration and development in untreated wheat caused 29% corrected mortality. Pre‐exposure combined with development in wheat treated with 1 mg kg−1 caused 30% corrected mortality. Thus, pre‐exposure of adults appears to have a greater effect on mortality of S. oryzae progeny than development of immature stages in treated grain. Development on treated grain had no effect on development rate. Pre‐exposure of adults did not appear to affect the rate of immature development, as assessed by X‐rays, but did slow the emergence of adults, lengthening development time by about 2 days. This significant, additive effect of pre‐exposure of adults on the mortality of their progeny will enhance the toxicity of chitin synthesis inhibitors such as chlorfluazuron, since most adults receive treatment when the immature stages are treated in crops either before they are harvested or in storage. Assessing the proportion of eggs that hatch from pre‐exposed adults would be a simpler bioassay for CSIs.

Dietary exposure of broiler breeders to aflatoxin results in immune dysfunction in progeny chicks

Broiler breeder hens were fed diets amended with 0 and 10 mg/kg (Trial 1) or 0, 0.2, 1, or 5 mg/kg (Trial 2) of aflatoxin (AF). Fertile eggs collected during 14 d of AF feeding were examined for AF residues. Various immunological endpoints were examined in chicks hatched from these eggs. Eggs collected at 7 d of AF feeding (Trial 1) had 0.15 to 0.48 ng/g of AFB1 and 0.22 to 0.51 ng/g of aflatoxicol, whereas eggs collected at 14 d of AF feeding had 0.05 to 0.60 ng of AFB1/g and 0.19 to 1.20 ng of aflatoxicol/g. In both trials, AF dietary exposure resulted in embryonic mortality and reduction in hatchability compared to controls. The AF progeny chicks in Trial 2 had total anti-SRBC antibodies similar to the controls during the primary antibody response. However, at 5 and 7 d after secondary SRBC injection, the antibody levels in the 1 and 5 mg/kg AF groups were lower than those of controls. Depression in anti-Brucella abortus antibodies occurred only in chicks from the 5 mg/kg AF group. Furthermore, phagocytosis of SRBC and reactive oxygen intermediate production by macrophages from AF progeny chicks were reduced as compared with the control chicks. The findings of this study imply that the progeny chicks from hens consuming a AF-amended diet may be increasingly susceptible to disease owing to suppression of humoral and cellular immunity.

Effects of temperature and length of exposure on the mortality of the carrot cyst nematode, Heterodera carotae

A hatchability level of 72% of eggs in Heterodera carotae cysts was notsignificantly affected by keeping the cysts in water at up to 40 C for 2 h, but percentage hatch was strongly reduced by keeping the cysts for 2 h in water at 47.5, 50 and 52.5 C. Keeping soil with cysts of H. carotae with a hatchability before treatment of 27% at temperatures between 32.5 and 45 C for 2 and 4 h did not affect percentage hatch of the eggs in these cysts but longer exposures increased it in two ways and decreased it in one way. This resulted in a positive correlation between percentage hatch and length of exposure up to a smaller maximum hatch the higher the temperature. At still longer exposures percentage hatch was negatively correlated with length of exposure. Whether the decrease is due to mortality of the eggs or, partly, to reversible inactivation remains to be investigated. In contrast to hatching tests with root diffusate, probably almost all eggs will hatch in the field under a host crop. Therefore, only the adverse effect of the heat treatments on hatching is ofpracticalimportance for the estimation of the effect of solarization. To separate it from the effects that increased percentage hatch in the tests, a model was made of the interaction of the separate effects. It was based on linear relationships between log duration of exposure to different temperatures and probit relative increase and decrease of hatching rates, and linear relationships between treatment temperature and log length of exposure required to obtain a given effect of one of the two increasing effects and of the decreasing effect of the treatments. The coefficient of variation of hatchabilities that were affected by the increasing but not by the decreasing effect of the treatments, relative to those predicted by the model, was 7.1% against 7.8% after treatments that had no effect on percentage hatch, whereas the relationship between log length of exposure and probit percent reduction of hatchability by the treatments was linear. The relationship between probit hatchability ( h ) due to the decreasing affect of the treatments and temperature ( T ) during t hours is probit h = a b log t dTr - T in which T is a reference temperature. For T - 10 T r r T = 45 C, a = 11.047, b = 1.44 and d = 0.637 for H. carotae . A good r T r approximation of this relationship is log h= k l t dTr - T with k = 2.453, - T T r l = 0.03735 and d = 0.637. These relationships probably also apply, with T r other parameter values, to other nematode species. To calculate the effect of fluctuating temperatures t dTr - T is replaced in the equations by T Sigma (t dTr - T). T

Excessive stimulation of Serotonin 2 (5-HT 2) receptors during late development of chicken embryos causes decreased embryonic motility, interferes with hatching, and induces herniated umbilici

The existence and functional significance of 5-HT 2 receptors in chicken embryos was studied by injecting the selective agonist dimethoxyiodophenylaminopropane (DOI), alone or in conjunction with the selective 5-HT 2 antagonist ritanserin (RIT), into domestic chicken eggs with embryos of varying ages. DOI caused dose-dependent reductions in hatchability and herniated umbilici in hatchlings. These effects were observed after injection early, mid, or late during embryonic development, with evidence of the toxic effects of DOI being greater in older embryos, probably due to 5-HT 2 receptor activation late in development, even after injecting DOI as early as on day 3 of embryogenesis. This is based upon the fact that embryos in eggs injected with DOI early continued to develop apparently normally, failing to hatch, often after pipping their shells. Additionally, those that hatched often did so with herniated umbilici, as did late-exposed embryos, indicating that DOI's effects upon this organ were most likely mediated during the prehatching period (i.e., days 18–20). The agonist's selectivity was confirmed by the capacity of RIT to dose dependently block both of these toxic effects of DOI. Reduced embryonic motility monitored on day 19, after injection of DOI on the evening of day 18, suggests that excessive activation of 5-HT 2 receptors late during development of this species interferes with some normal embryonic behaviors and physiological changes neccessary for inducing and/or maintaining the hatching process.

Reduction of Egg Hatch in Pear Psylla (Homoptera: Psyllidae) After Contact by Adults with Insect Growth Regulators

Pear psylla, Cacopsylla pyricola Foerster, adults that had contacted substrates treated with the insect growth regulators fenoxycarb or pyriproxyfen were allowed to oviposit on untreated plants. Eggs from treated insects had a reduction in hatch for up to 2 wk after treatment. The reduction was dependent on duration of contact with the treated surface. A pyriproxyfen-impregnated yellow tape has been developed and may assist in an attract-and-sterilize approach to management of pear psylla. Contact durations of as little as 5 s with this product reduced egg hatch in psylla for 1 wk after exposure.

Calcium uptake by chorioallantoic membrane: effects of vitamins D and K

The chorioallantoic membrane (CAM) of birds is an epithelial tissue that actively transports large amounts of Ca during embryonic development. In this study the effect of vitamins D and K on Ca uptake by the CAM was studied. Four dietary treatments were used to produce eggs that are the following: deficient in vitamins D and K (-D/-K), sufficient in both (+D/+K), or deficient in one and sufficient in the other (-D/+K or +D/-K). Vitamin D-deficient (-D) Japanese quail embryos (from hens fed 1,25-dihydroxyvitamin D3) do not hatch because of severe Ca deficiency resulting from their inability to obtain Ca from shell, whereas vitamin K deficiency results in only 14% reduction in hatchability. The results demonstrate that Ca uptake by CAM is vitamin D dependent and only slightly vitamin K dependent. Ca-binding activity of CAM extracts was unchanged by vitamin K deficiency, and only a small increase was provided by vitamin D treatment. Vitamin D stimulated both Ca entry and exist from the chorion cells as indicated by the increased accumulated 45Ca in +D embryos. We conclude that vitamin D is essential for the utilization of eggshell Ca by the developing embryo and hence its survival, suggesting that Ca transport across the CAM is largely a vitamin D-dependent process.

Inbreeding effects on competition in Tribolium

AbstractWhen replicate cultures of T. confusum and T. castaneum are husbanded together under identical treatment conditions, sometimes T. confusum eliminates T. castaneum, and other times, T. castaneum wins (i.e., competitive indeterminacy occurs). While several plausible explanations were advanced, the results of Mertz et al. (1976) implicated demographic stochasticity and not classical genetic founder effect as the predominant factor influencing the identity of the winning species. They also observed, however, that the size of the founding population had an influence on the competitive strength of T. castaneum. The present study shows that the decline in competitive strength that accompanied decreasing founder size in T. castaneum can be amply explained by simple inbreeding depression. The eggs of inbred adults showed an approximate 15% reduction in hatchability when compared to outbred adults. No evidence was found that the decrease in competitive strength was due either to prior history differences or reduced genetic heterogeneity of the founding adults.