Percentage Egg Hatch Research Articles

Effects of commonly used disinfectants on bacterial load, hatchability and survival of Bluefin Sea bream (Sparidentex hasta) eggs

The efficacy of four chemical reagents, iodophor, formalin, hydrogen peroxide and bronopol as fish egg surface disinfectants were evaluated in bluefin sea bream (Sparidentex hasta). Fertilized eggs were counted and subjected to a static bath dip treatment in different concentrations of the above chemicals for 4 min before being incubated at 20 ± 0.5°C for 40 h. Treatment efficacy of the different disinfectants was evaluated by assessing the bactericidal activity, egg hatch percentage and survival of larvae up to 3 days post hatch. Results showed that iodophor at medium concentrations (75 and 100 ppm) was the best of all tested disinfectants in bacterial killing ability (12% reduction in the bacterial counts), egg hatching per cent (99.8% and 99.6% respectively) and larval survival up to 3 days post hatch (50.8% and 54.8% respectively). Formalin was the second best disinfectant at levels of 100 and 150 ppm. Hydrogen peroxide gave good results compared with the control while, bronopol showed discouraging results. In conclusion, iodophor appeared to be suitable for bluefin sea bream eggs disinfection with a 4 min exposure to 75–100 ppm when applied 14–16 h after egg fertilization.

Prey infected with nucleopolyhedrovirus is preferred by the predatory stink bug Eocanthecona furcellata without altering its field fitness

Preference tests using the hemipteran predator Eocanthecona furcellata Wolff showed that nymphs and adults showed a constant preference towards virus-infected Spodoptera litura larvae. Adults feeding on healthy larvae throughout their life handled and consumed their prey quickly as compared to those feeding on infected prey, the differences being significant. Developmental time, survival rate, pre-mating period, sex-ratio and incubation period of E. furcellata that were reared on experimental plants infested with healthy larvae of S. litura as lifetime prey for all stages (control), healthy larvae during nymphal stage and infected larvae for adult stage, infected larvae for nymphal and healthy larvae for adult stage and infected larvae as lifetime meal for all stages of E. furcellata did not vary significantly. However, a significant reduction in body weight, fecundity, longevity and percent egg hatchability was observed when E. furcellata were fed on infected larvae as lifetime meal. The results revealed that the virus-infected larvae, relative to healthy larvae, had significant effect on prey preference of predators, but feeding on virus-infected prey had no adverse effect on its field fitness except on lifetime meal, which may not hold true under field conditions.

Frequency and Distribution of Extended Diapause in Nebraska Populations of <I>Diabrotica barberi</I> (Coleoptera: Chrysomelidae)

The frequency of extended diapause in populations of the northern corn rootworm, Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae), was measured in eastern Nebraska. Adult collections were made during late summer in 2008 and 2009 from eight sites each year (seven sites were consistent over years). Eggs were obtained from 12 to 20 females per site and were held on moist soil under appropriate temperature profiles to facilitate egg survival, diapause development, and diapause termination. Percentage egg hatch was recorded after the first and second year for the 2008 and 2009 collections. Additional extended diapause expression was estimated for the 2008 and 2009 collections by counting remaining live eggs after the second-year egg hatch was completed. These data also were used to estimate each site's maximum egg viability. Results collectively indicate that the extended diapause trait was present in all eastern Nebraska populations; however, significant variation in the frequency of extended diapause was observed within and among D. barberi populations (first-year mean percentage egg hatch range: 2008 collections: 4.5-38.6%; 2009 collections: 10.7-42.5%). Geographically, the highest incidence of extended diapause was found along a north-south transect in eastern counties of Nebraska that parallels the Missouri River. In general, the frequency of extended diapause was lower in sites found west of the north-south transect. This study contributes to the knowledge base needed to develop appropriate D. barberi management strategies in Nebraska. These data can be used to pinpoint areas of Nebraska that may have the greatest risk of economic injury in first-year corn (Zea mays L.) when D. barberi densities are high.

Development of the predator Eocanthecona furcellata on different proportions of nucleopolyhedrovirus infected Spodoptera litura larvae and potential for predator dissemination of virus in the field

The present work aimed to determine the impact of nucleopolyhedrovirus (NPV) on the development of Eocanthecona furcellata Wolff and to measure the infectivity of NPV discharged through its faeces. Developmental time, survival rate, sex ratio and incubation period of the predator reared on different proportions of healthy and NPV infected S. litura larvae as lifetime meal did not vary significantly. However, when the proportion of infected prey in the predator’s lifetime meal exceeded 50 % significant reductions in body weight, fecundity, longevity and percent egg hatchability were noticed. The virus did not show detrimental effect on the developmental biology of the predator in the subsequent generations when offspring emerging from nymphs fed only on virus infected prey throughout their life were reared on 50 % of infected prey. Therefore, adverse effects on E. furcellata are unlikely in the field as the predator is not expected to consume more than 50 % of infected prey even if the virus application is done at recommended dose. Under field conditions, it was found that increased proportions of infected prey enhanced the dissemination of viral inoculum through the faeces of the predators and the subsequent infection in S. litura larvae ranged from 22 to 52 %.

Effect of passage through the gut of Eocanthecona furcellata on Spodoptera litura multiple nucleopolyhedrovirus infectivity and its subsequent dissemination

Infectivity of Spodoptera litura multiple nucleopolyhedrovirus (SpltMNPV) was compared between before (P0) and after (P1–P4) passage in subsequent generations through the gut of Eocanthecona furcellata. Viable virus was detected in E. furcellata feces up to 6 days after feeding on infected S. litura larvae. NPV mortality ranged between 93% and 10% when test larvae were exposed to polyhedra voided in feces collected after 1 and 6 days post-infected meal, respectively. The mean number of polyhedral occlusion bodies (POBs) in excreta and their infectivity (%) at all passages did not vary significantly. The comparison of observed LD50 and ST50 values among all passages did not reveal significant differences owing to their overlapping confidence limits. The gut-passed virus did not show a detrimental effect on survival rate, longevity, fecundity and percent egg hatchability of E. furcellata in the subsequent three generations. A field trial was also conducted to estimate virus dissemination through feces of predators that were fed upon prey infected with polyhedra before passage, after passage and healthy (control) prey and subsequently released on cabbage plants. An additional viral mortality up to the magnitude of 13–17% was noticed in the former two treatments. However, within these two treatments the viral mortality did not vary significantly. It was concluded that E. furcellata disseminated the virus through their feces into the ecosystem without any adverse effect to it and infectivity of the SpltMNPV is not altered after passage through the gut of the predator.

Effects of high temperature on the eggs of Aedes aegypti (L.) and subsequent stages developed therefrom

The eggs laid by the emerged Aedes aegypti (L.) (Diptera: Culicidae) females were treated with high temperature at 35ºC at different exposure periods, viz., half an hour, one, two, four, eight and 24 hours, separately along with their control. At different exposure periods at 35ºC and control - the percentage of egg hatching ranged from 59 to 97; larval and pupal mortality ranged from zero to 12 and 3 to 14 per cent, respectively. Larval and pupal periods were 76 to 115 and 33 to 42 hours, respectively. Lengths of 2nd, 3rd, 4th instars were 3.615 to 4.518; 5.575 to 6.455 and 7.13 to 7.62 mm, respectively. Mean diameters of the head capsule of 1st, 2nd, 3rd and 4th instar larvae were 0.243 to 0.336, 0.387 to 0.476, 0.644 to 0.695 and 0.723 to 0.907 mm, respectively. Length of the cephalothorax of pupae was 1.49 to 1.907 mm. Body lengths of male and female adults were 2.9 to 3.00 and 3.33 to 3.51 mm, respectively.
 Dhaka Univ. J. Biol. Sci. 22(1): 9-20, 2013 (January)

Development and fecundity rate of Tribolium castaneum (Herbst) on Distillers Dried Grains with Solubles

This research focused on the influence of two samples of corn Distillers Dried Grains with Solubles (DDGS) obtained from an “old” generation dry-grind fuel ethanol plant as a food and oviposition resource for red flour beetle, Tribolium castaneum, in contrast with traditional flour (90%)/yeast (10%) diet. Larval development was significantly faster on a flour/yeast diet (18.6 d) compared to the DDGS sample 1 (44.1 d) and DDGS sample 2 (34.5 d). DDGS sample 1 had the highest larval mortality (38.7%) with a wider mortality range (6.7–66.7%) compared with flour/yeast (4.4%, range 0–14.3%) and DDGS sample 2 (7.1, range 0–26.7%). Both DDGS diets and the flour/yeast diet had no significant influence on egg incubation period or pupation time and percentage of egg hatching or pupal mortality. Additionally, fecundity was significantly lower on DDGS compared to the flour/yeast diet (18.0, 36.5, and 175.5 eggs per female on DDGS sample 1, DDGS sample 2, and flour/yeast diet, respectively). These results indicate that this type of DDGS is not a suitable developmental diet compared to the standard laboratory diet and that the addition of this type of DDGS to animal feeds should not increase feed vulnerability to flour beetle infestation. A comparison of DDGS samples by particle size indicated that the larger particle size, sample 1 was less suitable for T. castaneum oviposition and development.

<i>In vitro </i>anthelmintic effects of <i>Artemisia afra</i> and <i>Mentha longifolia</i> against parasitic gastro-intestinal nematodes of livestock

Gastrointestinal nematodes are the most widespread and economically important class of the helminths. The major threat posed by nematode infections is the productivity loss due to their ability to disrupt nutrient utilization of the livestock resulting in hunger and malnutrition. Acetone and aqueous extracts were prepared from Mentha longifolia and Artemisia afra and tested on egg hatch, larval development and larval mortality assays at three concentrations 2.5, 5.0 and 7.5 mg/mL. Certain percentages of egg hatch and larval mortality were inhibited by both plants; however, larval development was totally inhibited at all concentrations as compared to the negative control. Generally the acetone extracts from the two plants were most effective against parasitic gastrointestinal nematodes of livestock. This report therefore validates the folkloric use of these species in the management of internal parasites by the Basotho of the eastern Free State Province of South Africa.

Assessment of molluscicidal activity of essential oils from five Azorean plants against Radix peregra (Müller, 1774)

The molluscicidal activity of essential oils from two endemic (Juniperusbrevifolia; Laurus azorica) and three introduced (Hedychium gardnerianum; Pittosporum undulatum; Psidium cattleianum) Azorean plants against the snail Radix peregra was studied under laboratory conditions. Essential oils from leaves of H. gardnerianum, L. azorica and J.brevifolia presented promising molluscicidal activity on both adults and juveniles stages of R. peregra. The molluscicidal activity of these essential oils was found to be both time and concentration dependent. Lethal concentrations (LC50) varied between 15.4 (L. azorica) and 44.6ppm (H. gardnerianum) for juveniles and from 45.3 (H. gardnerianum) to 54.6ppm (J. brevifolia) for R. peregra adults. Ovicidal effect, calculated as percentage of egg hatching, at 100ppm concentration, was observed in essential oils from P. undulatum flowers (4.2% of hatching) and leaves of H. gardnerianum (4.9%), L. azorica (7.4%) and J. brevifolia (17.7%). The present study is the first attempt to assess the molluscicidal potential of some Azorean plants essential oils against a Lymnaeidae snail. In fact, the H. gardnerianum, L. azorica and J. brevifolia can offer natural alternative tools for the control of R. peregra population, but more research is needed in order to determine the mode of action of these oils and determine the side effects on the ecosystem where this freshwater snail occurs.

Impact of combined action of Neem and Eucalyptus oil volatiles on different stages of Corcyra cephalonica (Lepidoptera: Pyralidae)

Combined action of neem (Azadiracta indica) and eucalyptus (Eucalyptus sp.) oil volatiles causes a sharp reduction in percent egg hatchability in rice moth, Corcyra cephalonica (Stainton) (Lepidoptera: pyralidae) when freshly laid eggs were exposed to these volatiles for 24 hours. A marked decline in egg output and egg hatchability in reproductive pairs, was observed whose larvae were allowed to develop in a programmed manner in an environment, laden with combined action of selected volumes of neem and eucalyptus oil or when both the sexes of these pyralids, were confined for the prescribed limited period, in such odorous environment. A significant reduction in glycogen, lipid and protein level and an increase in free amino acids was noticed in testes and ovaries of these pyralids, when breeding pairs were exposed to the selected volatiles for a period of six hours only.

Biological effects of three Annona species on Callosobruchus chinensis: A green alternative for storage pest management

Plants have been known as a rich source of bioactive chemicals. These have been exploited in insect-pest management strategies as repellents, feeding deterrents, ovipositional deterrents and in many other ways in the biology of insects. The possible use of Annona species as eco-friendly alternatives to synthetic insecticides for the management of Callasobrucus chinensis in legumes was investigated from this perspective. In the present study, methanol extracts of leaves of Annona squamosa (Sugar apple), A. reticulata (Custard apple), and A. glabra (Pond apple) were evaluated to determine their effects on the oviposition, egg incubation and hatchability of C. chinensis. The effect of leaf extracts on the viability of cowpea seeds was also determined. Three doses (2.5, 7.5 and 12.5g/l) of leaf extracts were used in all tests. All the extracts tested resulted in significant reduction in oviposition in females. This reduction was dose-dependent and increased with the increase of dosage. Extracts of A. squamosa induced significantly the highest oviposition deterrence of 49.4% in the insects at the highest dose of 12.5g/l. A. reticulata (42.5%) and A. glabra (32.3%) on the other hand caused respectively lower deterrence. No deterrence of oviposition (0.0%) was observed with the control. In contrast, egg hatchability decreased with the increase of the dosage of extracts. A. squamosa at the highest dose evoked the lowest percentage egg hatch (35.2%) while 96.4% eggs hatch was observed with the control. Egg hatchabilty caused by A. reticulata extract at the same dose was 70.3% which was twice as much observed with A. squamosa. Furthermore, incubation period of eggs also increased with time and dose. In comparison to the control (4.0 days), the highest incubation period was recorded from eggs treated with A. glabra at the dose of 12.5g/l (7.7 days) followed by A. squamosa (6.9 days). None of the plant extracts elicited any adverse effects on the germination capability (viability) of cowpea seeds which varied between 99-100%. The overall results of the study indicate that all three Annona species have a positive impact on the management of this beetle. Moreover, A. squamosa could be considered as the most effective compared to the other two species. As all three plant species tested are locally available, the outcome of this study may certainly help in paving the way for their usage against post-harvest pests.

Multiple mating in Anastrepha fraterculus females and its relationship with fecundity and fertility

The occurrence of female remating has been widely reported in insects and the frequency at which it occurs and the factors driving females’ remating behavior have been shown to be both species specific and variable within species. Herein, we studied the remating behavior of females from a well established laboratory colony and a wild population of the South American fruit fly, Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae), under laboratory conditions. Latency to first mating (number of days from the onset of the experiment until the first copula) was shorter for remating females than for females that did not remate. Two-day fecundity was higher for females that did remate than for monogamous females. Egg hatch was sustained after remating and was not affected by the number of times the female mated. However, when females willing to remate were prevented from doing so, percent egg hatch showed a significant drop. These results and the fact that remating occurred more often in more fecund females than in less fecund ones suggest that remating may be a response to sperm depletion. Remating frequency was similar in laboratory and wild flies, but 2-day fecundity was higher for laboratory than for wild females of similar mating status. Also, the length of the refractory period (time between first and second copulation) was longer for wild than for laboratory females. Differences between strains could be the result of artificial selection. Results are discussed from a theoretical and applied perspective in the context of direct benefits to females.

Response ofBemisia tabaci(Hemiptera: Aleyrodidae) to Vapor Pressure Deficit: Oviposition, Immature Survival, and Body Size

AbstractWhiteflies cause major agricultural problems in environments ranging from arid to humid climates on a global scale. A study was conducted on the effects of vapor pressure deficit (VPD) on oviposition, hatching, body size, and survival of immature B-biotype sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). Experiments were conducted at VPD conditions of 0.5, 1.7, and 2.7 kPa to represent low, medium, and high VPD environments, respectively. The study was conducted at 26°C with insects reared on collard, Brassica oleracea ssp. acephala de Condolle. The rate of oviposition was decreased at the highest VPD treatment. However, percentage egg hatch was not significantly affected by the treatments. More time was required for eggs to hatch at a high (2.7 kPa) compared with a low (0.3 kPa) VPD in a separate experiment. Overall survival to the adult stage was decreased at the highest VPD (≈50%) compared with the other two VPD environments (≈75%). Sizes of males and females were different, as is well known, but VPD had little significant effect on adult body size (length and width). The size effect was erased when the F2 generations from the different treatments were reared under a common environment. Insect population models that include the most relevant environmental parameters can offer the best estimation of life-history events. These results help elucidate the ecology of B. tabaci and indicate that extremes in ambient moisture can have an impact on populations.

Toxicity of methylmercury injected into eggs when dissolved in water versus corn oil

In a previous study, the embryotoxicity of methylmercury dissolved in corn oil was compared among 26 species of birds. Corn oil is not soluble in the water-based matrix that constitutes the albumen of an egg. To determine whether the use of corn oil limited the usefulness of this earlier study, a comparison was made of the embryotoxicity of methylmercury dissolved in corn oil versus water. Mallard (Anas platyrhynchos) and chicken (Gallus gallus) eggs were injected with methylmercury chloride dissolved in corn oil or water to achieve concentrations of 0, 0.2, 0.4, 0.8, and 1.6 µg/g mercury in the egg on a wet weight basis. Hatching success at each dose of mercury was compared between the two solvents. For mallards, 16.4% of the eggs injected with 1.6 µg/g mercury dissolved in water hatched, which was statistically lower than the 37.6% hatch rate of eggs injected with 1.6 µg/g mercury dissolved in corn oil, but no differences in hatching success were observed between corn oil and water at any of the other doses. With chicken eggs, no significant differences occurred in percentage hatch of eggs between corn oil and water at any of the mercury doses. Methylmercury dissolved in corn oil seems to have a toxicity to avian embryos similar to that of does methylmercury dissolved in water. Consequently, the results from the earlier study that described the toxicity of methylmercury dissolved in corn oil to avian embryos were probably not compromised by the use of corn oil as a solvent.

Effects of the Insect Growth Regulator, Novaluron on Immature Alfalfa Leafcutting Bees,Megachile rotundata

Alfalfa leafcutting bees, Megachile rotundata F. (Hymenoptera: Megachilidae), are the most common pollinators of alfalfa in the Pacific Northwest. Reports from users of M. rotundata in Idaho, Utah and Colorado have indicated exceptionally poor bee return from fields treated with novaluron to control Lygus spp. Our goal was to evaluate novaluron toxicity to immature M. rotundata using two different possible mechanisms of exposure. One goal was to assess immature mortality via treating nectar-pollen provisions and adults with novaluron. Immature M. rotundata mortality in all novaluron provision dosing treatments was significantly higher than the water or blank controls, providing evidence that novaluron is toxic to progeny in nest cells. The mean cumulative frequency showed that more eggs and 1st–2nd instars died compared to older instars. Female M. rotundata nested similarly in field cages during the field cage experiment; however, there was greater immature mortality in cages where females were fed sugar-water + novaluron compared to sugar-water only. Although females provided adequate provisions, there was a low percentage of egg hatch and larval development when females ingested novaluron before mating and nesting. Novaluron was also present in egg provision of bees collecting resources from novaluron-sprayed plants. At least 84% of progeny died when the females were allowed to mate and nest 24 hours after a novaluron application. Novaluron could be contributing to poor bee return in alfalfa grown for seed. Timely insecticide applications to suppress Lygus spp. is an important consideration to improve ongoing bee health.

The effect of Bacillus thuringiensis in Phthorimaea operculella (Zeller) (Lepetoptera:Gelechiidae)

The following dilutions -710X46, -610X46, -510X46 of Bacillus thuringiensis were used for bioassay against the different larval instar of the potato tuber moth Phthorimaea operculella by the spraying method, the results showed that there was no significant influence in the percentage of egg hatching in comparison with the control. The sensitivity of larval stages was reduced with the increasing the age and exposure period. The study also showed that the larvae infected with B.t. stopped feeding, movement and a general paralysis causing the death of larva after (24-48) hours , and the larva color was changed from the natural waxy colour to brown finally to the black after death.

The effect of Bacillus thuringiensis in Phthorimaea operculella (Zeller) (Lepetoptera:Gelechiidae)

The following dilutions -710X46, -610X46, -510X46 of Bacillus thuringiensis were used for bioassay against the different larval instar of the potato tuber moth Phthorimaea operculella by the spraying method, the results showed that there was no significant influence in the percentage of egg hatching in comparison with the control. The sensitivity of larval stages was reduced with the increasing the age and exposure period. The study also showed that the larvae infected with B.t. stopped feeding, movement and a general paralysis causing the death of larva after (24-48) hours , and the larva color was changed from the natural waxy colour to brown finally to the black after death.

Spinosad as an effective larvicide for control of Aedes albopictus and Aedes aegypti, vectors of dengue in southern Mexico

Field trials were conducted during the wet and dry seasons in periurban and semi-rural cemeteries in southern Mexico to determine the efficacy of a suspension concentrate formulation of spinosad (Tracer 480SC) on the inhibition of development of Aedes albopictus L. and Ae. aegypti Skuse. For this, oviposition traps were treated with spinosad (1 or 5 mg L(-1)), Bacillus thuringiensis israelensis (Bti, VectoBac 12AS), a sustained release formulation of temephos and a water control. Ae. albopictus was subordinate to Ae. aegypti during the dry season, but became dominant or codominant during the wet season at both sites. The two species could not be differentiated in field counts on oviposition traps. Mean numbers of larvae + pupae of Aedes spp. in Bti-treated containers were similar to the control at both sites during both seasons. The duration of complete absence of aquatic stages varied from 5 to 13 weeks for the spinosad treatments and from 6 to 9 weeks for the temephos treatment, depending on site, season and product concentration. Predatory Toxorhynchites theobaldi Dyar and Knab suffered low mortality in control and Bti treatments, but high mortality in spinosad and temephos treatments. Egg counts and percentage of egg hatch of Aedes spp. increased significantly between the dry and wet seasons, but significant treatment differences were not detected. Temephos granules and a suspension concentrate formulation of spinosad were both highly effective larvicides against Ae. aegypti and Ae. albopictus. These compounds merit detailed evaluation for inclusion in integrated control programs targeted at Ae. aegypti and Ae. albopictus in regions where they represent important vectors of human diseases.

Effect of a High Dose of Three Antibiotics on the Reproduction of a Parthenogenetic Strain of <I>Folsomia candida</I> (Isotomidae: Collembola)

Folsomia candida Willem (Isotomidae: Collembola) is an edaphic parthenogenetic species commonly used in ecotoxicity studies. We exposed F. candida to a high dose of three antibiotics, tylosin, ampicillin, and oxytetracycline, that target different bacterial groups. Possible toxic effects were assessed through egg production, hatching, and body size. All three antibiotics caused toxic effects. Treatment with oxytetracycline proved the most toxic. This group showed the smallest body size and lowest number of eggs laid, likely the result of a combination of antibiotic toxicity and avoidance of the antibiotic spiked food. Active toxin avoidance by F. candida in toxicological assays may play a role in minimizing their exposure to toxic compounds. Despite the administration of high doses of oxytetracycline, F. candida individuals remained infected with the intracellular bacteria Wolbachia indicating that this strain is resistant to this antibiotic or that the host or its gut flora had detoxified the compound. An increase in percent egg hatch with time was seen in the ampicillin and oxytetracycline treatments, indicating a possible accommodation of the host and/or gut-flora to these antibiotics.

Parental age at mating affects reproductive attributes of the aphidophagous ladybird beetle, Coelophora saucia (Coleoptera: Coccinellidae)

Ageing and its affect on life attributes have not been widely explored in ladybirds. The present study investigates the influence of female and male age at mating on the reproductive attributes of the ladybird beetle, Coelophora saucia (Mulsant). All reproductive attributes, viz. fecundity, percentage egg hatch, pre-oviposition, oviposition and post-oviposition periods were found to be influenced by the ages of both females and males at mating. This is unlike the results of previous studies on ladybirds, where male age was found to influence only percentage egg hatch. The influence of male age at mating on fecundity and reproductive periods is probably due to age influenced variation in seminal proteins, which influence fecundity and when the eggs are laid.