Egg Incubation Period Research Articles

Energy Expenditure of Female Barn Swallows Hirundo rustica during Egg Formation

The energy expenditure of female barn swallows (Hirundo rustica) was measured during the period of egg formation using the doubly labelled water (DLW) technique. Mean field metabolic rate (FMR) was 104-112 kJ d⁻¹ (standard deviation [ SD] = 22, n = 12), dependent on assumptions used in the calculations. The energy expenditure of female swallows did not differ significantly between egg formation, incubation, and nestling-rearing periods. Water turnover rate of laying females was 18.4 mL d⁻¹ (SD = 2.0, n = 12). The amount of egg material deposited during energy expenditure measurements was determined for 11 of the birds by feeding them lipophilic dye, which marked the outside of each rapidly developing ovarian follicle. The energy content of egg material deposited in 24 h averaged 4.9 kJ (SD = 2.3, n = 11), which represented 4.5%-4.9% of FMR. Variation in FMR was not correlated with egg deposition. The mean clutch size of swallows for which FMR was measured during egg formation was slightly but significantl...

Studies on the ectoparasitoid, Anisopteromalus calandrae How. (Hymenoptera: Pteromalidae) as a biocontrol agent against the lesser grain borer, Rhyzopertha dominica (Fab.) in Saudi Arabia

Anisopteromalus calandrae How. was reared in the laboratory on full grown larvae of Rhyzopertha dominica (Fab.). The incubation period of the parasitoid's egg was 36 h at 26 °C and 27 h at 30 °C. The larval stage lasted 6.9 and 5.4 days, the prepupal stage lasted 23.6 and 17.8 h, and the pupa lasted 5.4 and 4.6 days at 26 and 30 °C, respectively. The total developmental time (from egg to adult) averaged 18.9 and 14.6 days at 26 and 30 °C, respectively. Sex ratio was 2.1♀:1♂ in the field and 2.3♀:1♂ in the laboratory. The daily and total numbers of eggs laid/female were 6.7, 150.4 and 8.3, 132.6 at 26 and 30 °C, respectively. The parasite female and male, fed on honey, lived for 32.6 and 25.5 days at 26 °C, respectively. Percentages of parasitism recorded in the laboratory were, respectively 69.5, 43.3, 30.1, 16.8 and 0 on R. domenica, Sitophilus granarius, Bruchus rufimanus, Trogoderma granarium and Oryzaephilus surinamensis. The parasitoid was active in the field from February to November, but reached its peak in July with a 59.3% parasitism on R. dominica.

Development, Survivorship, and Reproduction of Amblyseius largoensis (Acari: Phytoseiidae) on Selected Plant Pollens and Temperatures

Effects of temperature and 4 plant pollens on the development, survivorship, and reproduction of Amblyseius largoensis (Muma) were evaluated. The average egg incubation period at 15, 20, 25, 30, and 35°C was 6.02, 3.26, 2.01, 1.45, and 1.95 d, respectively. The combined larval and nymphal developmental time (mean ± SD) decreased from 11.18 ± 0.55 to 3.21 ± 0.41 d and adult longevity from 39.45 ± 6.24 to 11.91 ± 5.33 d as temperature was increased from 15 to 35°C, respectively. No significant difference in adult longevity was observed when pollens from live oak, Quercus virginiana Miller, castor bean, Ricinus communis L., cattail, Typha domingensis Persoon, and pygmy date palm, Phoenix roebelenii O'Brien, were provided as food at 25°C. Survivorship was >90% when this predator was reared at 5 constant temperatures on 4 plant pollens as food, with the exception of egg hatch at 35°C. The highest intrinsic rate of natural increase ( rm = 0.265) and net reproductive rate ( ro = 19.27)were obtained at 2.5°C compared with the life table parameters derived from the other 4 constant temperatures. When pollens of live oak, castor bean, cattail, and pygmy data palm were provided as single food sources at 25°C, life table parameters indicated that live oak pollen is the most suitable food source, followed by castor bean and cattail pollens.

The sterilizing effect of pour-on flumethrin on the camel thick, Hyalomma dromedarii (Acari: Ixodidae)

The relationship between the efficacy of 1% flumethrin in pour-on formulation on the fertility of engorged female Hyalomma dromedarii and exposure time was investigated. Using a contact method, ticks were exposed in vitro to 87 μg active ingredient for 1, 5, 10, 30 or 720 min. Fertility inhibition was related to the exposure time. No significant effect was obtained after 1 min exposure, but 5 or 10 min exposure reduced the percentage of females ovipositing, egg mass weight, number of eggs, percentage of females laying eggs that hatch and the conversion efficiency of female weight to egg mass weight. The action of flumethrin was highly pronounced after 30 min; out of ten females, only one oviposited on the 19th day after exposure and the eggs did not hatch. Females exposed for 12 h were paralysed and showed complete sterilization. The pre-oviposition and egg incubation periods of females exposed for 1, 5 or 10 min were prolonged due to the action of the drug.

Laboratory-reared larval stages of Dissodactylus mellitae (Decapoda: Braohyura: Pinnotheridae) and developmental patterns within the Dissodactylus species complex

Eggs of Dissodactylus mellitae were incubated for 9–10 days at 28 °C and larval development consisted of three or four zoeal stages and a megalopa. Beginning with the first zoea, the mean duration of successive stages was 5, 3, 4, and 5 days, the first megalopa appearing 10 days after hatching. Among the megalopae obtained, 87% molted from a third zoea, whereas 13% passed through a fourth zoeal stage before metamorphosing to a megalopa. The last zoea is not considered a substage, since it showed no morphological variation, and molting resulted in growth and consistent morphological changes. Compared with other species within the Dissodactylus complex, the development of D. mellitae represents an intermediary level between three and four zoeal stages. The number of zoeal stages of the ancestor of the Dissodactylus species complex cannot presently be inferred. Among larvae of Dissodactylus s.str., D. mellitae zoeae are characterized by a small carapace with relatively long spines and megalopae by a carapace that is as wide as long. The latter can also be distinguished among Atlantic species by the lack of a dactyl on maxilliped 3, by the absence of serrate setae on the chela, and by the blade of the scaphognathite bearing 5 simple setae but lacking a plumodenticulate seta. Within the Dissodactylus species complex significant relationships were determined between egg size and incubation period and between egg size, carapace length, and time to reach the megalopa stage. Another significant relationship was determined between egg size and the duration of the first zoeal stage, but this correlation did not hold for subsequent stages. Differences in survival rates from those of other species may be attributable to differences in diet and the use of antibiotics.

Alberprosenia malheiroi Serra, Atzingen & Serra, 1987 (Hemiptera, Reduviidae). Redescription and bionomics

Alberprosenia malheiroi n. sp. first became known through an informal publication of a paper submitted a Congress, in 1980. The same diagnosis with a photograph was published in 1987, but no formal description has yet been made. The present authors describe adults and immature instars, establish a sintypical series and introduce bionomic data and data on the rearing of this species in insectary. The most evident differences between A. malheiroi n. sp. and A. goyovargasi, the former generic species, are the general colour pattern which is completely black; the interocular area, wider than an eye in dorsal view; the acute apex in collar tubercules and the significantly larger size, almost double that of the latter specie. The eggs are small attach themselves to the substratum in groups of either 3 or 4, are elipsoid with no lateral flattening, having a convex and prominent operculum, without conspicuous structures. Nymphs have the typical tribal and generic characteristics in each stage, the anteocular region being shorter than the postocular one. Pilosity appears in the second instar and becomes more evident with instar development. A. malheiroi n. sp. was captured in a forest, in wild (palm-tree) ecotopes associated with bats or birds, in the State of Para, Brazil. Trypanosoma cruzi was not found in any specimens. These triatomines were reared in +/- 25 degrees C and +/- 60% RH, the insects are quick and fly without difficulty. They fed well on pigeons and bats but not on rats, mice or hamsters. The eggs incubation period was thirteen days on average, and the evolution time of the nymphal period was a hundred and thirty two days on average.

Embryonic development of central nervous system myelination in a reptilian species, Eumeces fasciatus

The myelin proteolipid proteins are a vital component of the vertebrate central nervous system (CNS), contributing essential functions to the development of the myelinating cells of the CNS and to the structure of CNS myelin. Alternative splicing of the proteolipid protein (PLP) gene to produce two related isoforms occurs in Mammalia, Aves, and Reptilia, but not Amphibia. As part of a long-term investigation into the function of the different isoforms of PLP, embryonic development, myelination, and PLP gene expression in reptilian CNS were examined. PLP gene expression was already substantial by day 19 (stage 39) of the 27-day Eumeces fasciatus egg incubation period. By day 21 of incubation, also stage 39, PLP mRNA was at peak levels; there was a significant amount of CNS myelination as demonstrated by electron microscopy of the spinal cord; and the reflexive motor response was evident. Although most axons were myelinated by the time of hatching, myelin sheaths continued to increase in size and compactness after hatching. The correlation of physiological development, CNS myelination, and expression of the PLP gene in the lizard corresponded well with the developmental pattern seen in mammals.

Biology of Triatoma nitida Usinger, 1939 in laboratory conditions (Hemiptera: Reduviidae)

Triatoma nitida is a wild species occurring in Mexico and Central America. In order to establish the length of its life cycle and transmission potential, the following parameters were observed: the incubation period, the interval between hatching, or moulting, and the first feeding; the number of blood meals and the time of development. The time-lapse before the bite, the length of feeding and the interval between the end of the blood meal and defecation, as well as the site of defecation were also analyzed. Average length of the egg incubation period was 18.2 days. Time interval between the food source offering and the bite was less than 4 min in 60% of the analyzed cases, except in the fifth instar, where only 38% of the insects began feeding in less than 5 min. The blood-sucking period was long and rising until the fifth instar, decreasing in adults, and ranging from 1 min to 2 and a half hours. Only 26% of the blood meals were followed by defecations within 20 min. The average length of the life cycle was 897.5 days.

Spring flood: a primary cue for hatching of river spawning Coregoninae

Increased water discharge during spring floods gives the primary cue for the start of hatching and drift of European vendace (Coregonus albula) and whitefish (Coregonus lavaretus) in the Norwegian River Lâgen. The drift increased with water flow for discharges between 50 and 850 m3∙s−1(vendace: R2 = 0.91; whitefish: R2 = 0.77). The length of hatching period, as judged from the drift, was negatively correlated with the increase in water discharge (vendace: R2 = 0.73; whitefish: R2 = 0.68). The length of the egg incubation period and time of hatching were not significantly correlated with the ambient water temperature. Two artificial floods (220 m3∙s−1), released before normal spring flooding, increased the total number of drifting Coregoninae larvae in the river. The first flood increased the number of vendace and whitefish larvae per second from 2.1 and 0.0 to 86.1 and 4.5, respectively, before returning to preflood levels. The second flood gave 18.9 and 1.8 individuals/s.

Life History of Immature Lyctocoris campestris (Hemiptera: Anthocoridae): Effects of Constant Temperatures and Relative Humidities

Life history of immature Lyctocoris campestris (F.), a predator of stored-product insects, was investigated at 17, 21, 25, and 29°C and ≍43, ≍58, and ≍75% RH in the laboratory. Most life history traits of L. campestris were influenced by temperature, but none of the traits was influenced by relative humidity. The egg incubation period was ≍7 d at 25-29°C, but increased sharply at temperatures <25°C. An equation was developed to predict egg incubation period over a range of temperatures. Egg hatch rate did not vary with temperatures nor with the relative humidities. The mean hatch rate ranged from 78 to 86% across different temperatures summed across 3 relative humidities. The instar-specific nymphal development also varied with temperature. The 2nd stadium was the shortest followed by the 3rd, 1st, and the 4th, and the 5th stadium was the longest across all 4 temperatures. However, the ratios of duration of nymphal stadia remained constant across all 4 temperatures tested. Total nymphal durations were 20.5, 27.6, 40.1, and 66.2 d at 29,25,21, and 17°C, respectively; all 4 were significantly different from one another. The relationships between temperature and instar-specific nymphal durations and total nymphal durations were described by the same equation for both females and males; total nymphal durations did not vary with sex. Nymphal survival rates ranged from 0.60 to 1.00 and did not vary significantly with temperature or relative humidity. Sex ratio (proportion of males) of emerging adults ranged from 0.40 to 0.70, but did not differ from 1:1. These life history data are reported in a manner useful for developing a computer model for simulating L. campestris population dynamics.

Mechanisms of Short Incubation Period in Brood-Parasitic Cowbirds

Field estimates of incubation periods of brood parasitic cowbirds (Molothrus spp.) indicate that they are unusually short given the sizes of their eggs. As a consequence, cowbirds usually hatch before host young, even though cowbird eggs are frequently larger. Field-estimated incubation periods, however, have an inherent uncertainty because of in- termittent attendance by incubating birds, and the mechanisms for early hatching are un- known. I report incubation periods of Shiny Cowbird (M. bonariensis) eggs under controlled conditions in the laboratory, and test the hypothesis that cowbirds exhibit accelerated rates of embryo development, by exploring two possible mechanisms for shortening the incubation period of cowbird eggs: (1) cowbird eggs may have a low energy content, which results in a short incubation period because yolk reserves are depleted earlier; or (2) cowbird embryos may have elevated growth rates, which would be reflected in their metabolic rates. Energy content of cowbird eggs was 23.8% lower than expected from egg mass. Mean incubation period in the laboratory was 11.7 days, which is 28.8% shorter than expected from egg mass, but close to the expected from energy content. Similarly, yolk-free, dry hatchling mass was lower than expected from egg mass, but not significantly different from the expected from egg energy content. These results support the hypothesis that cowbirds shorten incubation period by reducing the energy content of the egg, although it results in a slightly smaller hatchling. The hypothesis that cowbird embryos have elevated growth rates, in contrast, was not supported because embryos did not have higher metabolic rates than expected from their size. Although the evidence presented here is correlational, there is experimental evidence that reducing yolk reserves may act as a proximate cue for early hatching in other vertebrates. Received 7 June 1993, accepted 13 November 1993.

Development of Tabanus nipponicus (Diptera, Tabanidae) Confirmed by Laboratory-Rearing

The immature development of Tabanus nipponicus was studied by laboratory-rearing. Total duration of oviposition-to-emergence was 337 ± 15 days (mean ± SD) in males and 364 ± 20 days in females. The number of larval instars ranged from five to seven, on average six in both sexes. The incubation period of eggs was three to five days. Eggs hatched simultaneously from the same egg-mass. Larvae attained the last instar in autumn. The developmental time of last instar including hibernation averaged 281 ± 13 days in males and 310 ±26 days in females over three quarters of the whole immature period. Pupal duration averaged 14 ± 3 days in both sexes. Male adults emerged from mid June to late July and females from early July to early September. This species was univoltine.

Influence of the nature of the ingested blood on the gonotrophic parameters of Phlebotomus perniciosus under laboratory conditions

A laboratory study was conducted about the duration of developmental stages and the productivity connected with the type of blood meal ingested by the female of Phlebotomus perniciosus. The pre-oviposition and egg incubation periods are not affected whatever the blood ingested by the female. The shorter time required to achieve larval development (rabbit) and pupal development (hamster) governs the generation time, shorter than in the other hosts (dog and man). The productivity is greater when blood is ingested from the rabbit and the dog. This is mainly due to the smaller number of eggs retained in females with these hosts.

Oviposition, Fecundity, and Body Size of a Pestiferous Midge, Chironomus crassicaudatus (Diptera: Chironomidae)

Field-caught gravid female Chironomus crassicaudatus Malloch in central Florida laid egg masses mostly in the morning at onset of photophase in the laboratory. Fifty-seven percent of these females laid a second egg mass in their adult life. Number of eggs averaged 1,338 and 245 per mass in the first and second mass, respectively. Average egg incubation period was 2 d, with initiation and cessation of egg hatch occurring at 1.5 and 5 d after oviposition, respectively. Relationship of body size and fecundity of female C. crassicaudatus was studied by measuring wing length and examining number of eggs per mass and parity. Body size of nulliparous and of parous females had a significant linear relationship with dry body weight. Larger females had a significantly higher number of eggs per mass and percentage parity than small females.

Pathological lesions in larvae hatched from ovigerous females ofChasmagnathus granulata (Decapoda, Brachyura) exposed to cadmium

Morphological abnormalities were noted in larvae hatched from ovigerous females of the estuarine crabChasmagnathus granulata, exposed to 1 and 15 mg/l of cadmium during the egg incubation period. The highest concentration produced a significant incidence of hydropsy, atrophy of dorsal spine, pleon and pereiopods as well as enhancement of pigmentation. Some possible causes of these results are discussed and compared with the effects caused by other pollutants on the same species.

Notes on the biology and immature stages of West African sorghum head bugs Eurystylus immaculatus and Creontiades pallidus (Heteroptera: Miridae)

AbstractDetailed studies on the immature stages of the sorghum head bugs, Eurystylus immaculatus Odhiambo and Creontiades pallidus Rambur, were carried out in the laboratory at Samanko, Mali, during November 1991 to March 1992, and January to April 1993, and in the field in October 1993. Eggs of both species were laid in maturing sorghum (Sorghum bicolor) grains. The egg incubation period was 4–7 days in E. immaculatus, and 5–7 days in C. pallidus. There were five nymphal instars in both species. The total nymphal period was 6–11 days in E. immaculatus and 8–14 days in C. pallidus. The durations of first, second, third, fourth and fifth nymphal instars were 1–3, 1–2, 1–2, 1–3 and 1–3 days, respectively, in E. immaculatus, and 1–3, 1–2, 1–3, 2–3 and 2–4 days, respectively, in C. pallidus. All the immature stages of E. immaculatus are described and sketched.

Recruitment, Growth, Mortality, and Biomass Production of Larval and Early Juvenile Atlantic Tomcod in the Hudson River Estuary

We report on the dynamics of a closed population of larval and early juvenile Atlantic tomcod Microgadus tomcod in the lower Hudson River estuary. Previous Hudson River studies of this species were conducted farther upriver where the population is open, influenced by largescale, undetected migrations. We determined the date of peak hatching for Hudson River Atlantic tomcod to be 9–11 March in 1975 and 1976, after an egg incubation period estimated to be 61–70 d. The average length of larvae with full yolk sacs (assumed to be newly hatched) was 7.0 mm, and yolk absorption took 2–3 weeks. Our estimates for egg incubation period, larval length at hatching, and duration of the yolk-sac stage were considerably higher than the values typically cited for Hudson River Atlantic tomcod. Early growth of this coldwater species was enhanced by higher spring temperatures, but growth declined significantly from 2.9%/d to 1.3%/d as water temperature rose above 13°C in late May. Recruitment each year was estimated at 2–3 × 109 larvae, and daily mortality rates (Z) of 0.0503–0.0823 reduced the 1976 cohort by about 99% within 10–11 weeks from peak hatch. Cumulative biomass production during March-May was 130,000 kg for the 1976 cohort. Prey potential, in the form of cohort biomass, peaked at 36,000 kg in late May, prior to the midsummer recruitment of other juvenile prey species.

Interannual variation in the breeding biology of the Antarctic prion Pachyptila desolata at Bird Island, South Georgia

Interannual variation in aspects of the breeding biology of Antarctic prions was studied for three summers (1989–1992) at Bird island, South Georgia. Egg size, mass and incubation period remained constant. Laying, hatching and fledging were significantly delayed and less synchronous in 1991/92 (range of laying dates 51 days compared to 10–15 days in the two other seasons). This was due to an unusually cold and protracted winter, with ice blocking burrows into the spring, restricting availability of nest sites. Brooding lasted longer in 1991/92 but the overall fledging period was unchanged. Skeletal growth rates did not vary amongst years; growth in mass was slower in 1989/90 but fledging mass was similar in all three years. In 1989/90 and 1991/ 92 later hatched chicks grew (in mass) faster. The survival of chicks from hatching to fledging did not vary amongst years or with hatching date. Feeding frequency was similar between years, once allowance had been made for starlit nights. Thus late and asynchronous breeding in 1991/92 did not result in reduced breeding success either through predation or starvation.Crustaceans formed 98–99% of the mass of the identifiable portion of regurgitated food samples. Significant annual variation was found within these crustaceans with the presence of krill (least in 1990/91) being inversely related to that of amphipods and copepods. There was no relationship between diet composition and chick growth or survival. Other seabird species, lacking the morphological specialization for feeding on copepods and amphipods, had very low breeding success in 1990/91, when krill was scarce.

Comparative reproduction and nonparasitic development of Boophilus microplus and hybridized Boophilus ticks (Acari: Ixodidae) under natural field conditions in subtropical South Texas

The reproductive biology and nonparasitic development of Boophilus microplus (Canestrini) and hybridized Boophilus ticks (B. annulatus (Say) male x B. microplus female) held under natural field conditions in south Texas throughout the year were compared. Comparisons between the two types of ticks indicated that the ovipositional biology (percentage of ovipositing females and number of eggs laid) of the females favored hybrid ticks during some months and B. microplus ticks during other months. However, on a year long basis, there was virtually no difference in the percentage of ovipositing females or in the number of eggs deposited by hybrid females as compared to B. microplus. The duration of each nonparasitic development period (preoviposition period, incubation period of eggs, and larval longevity) showed that both types of ticks had very similar developmental and survival rates during the year. Generally the difference in duration of each of the nonparasitic parameters was < 8 days, leading to a high degree of synchrony of the nonparasitic developmental rates between the two types of ticks. On the other hand, egg hatchability of hybrid ticks was consistently lower than pure-strain B. microplus throughout the year with significantly lower hatch rates occurring in April, July, August, October, and November. Thus, results obtained on percentage of ovipositing females, number of eggs laid, preoviposition period, incubation period of eggs, and larval longevity provide encouragement for the possible use of sterile hybrid males as a means of eliminating a native B. microplus population. In contrast, results of the egg hatchability of the two types of ticks indicate that the selective advantage afforded to B. microplus could have an adverse affect on the success of a sterile hybrid male program by making the number of hybrid ticks necessary to eliminate a native population prohibitively high.

Immunisation of dogs, hamsters and guinea pigs against Rhipicephalus sanguineus using crude unfed adult tick extracts

Naive experimental groups of dogs, hamsters and guinea pigs were inoculated three times subcutaneously with unfed adult extract of the tick Rhipicephalus sanguineus and challenged with adult R. sanguineus to evaluate resistance. The acquisition of resistance was based on alterations of some reproductive and feeding performance parameters of female ticks such as female and egg mass weights, engorgement, pre-oviposition and incubation periods, larval hatchability rate and efficiency rates of female ticks in converting their food reservoir to eggs and larvae. Dogs did not develop resistance under these experimental conditions; guinea pigs and hamsters, to a lesser extent, acquired an effective immunity to ticks as demonstrated by the impairment of the reproductive and feeding performance. However, the resistance induced by inoculation of the extract in the rodents seemed not to be as efficient as that induced by successive infestations.