Oviposition Rate (oviposition + rate)

Distribution by Scientific Domains


Selected Abstracts


Adult mortality and oviposition rates in field and captive populations of the blowfly Lucilia sericata

ECOLOGICAL ENTOMOLOGY, Issue 6 2004
K. M. Pitts
Abstract., 1. Adult mortality and oviposition rates were determined for populations of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae). This species is of economic importance as the primary agent of sheep myiasis throughout north-western Europe. 2. Populations of marked flies in six, 1 m3, outdoor field cages and unmarked wild flies at two farms in south-west England were studied simultaneously between May and September 1998. 3. In the field, wild female L. sericata were caught and aged using a combination of wing-fray and ovarian dissection techniques. Survivorship analysis gave estimates of mortality of 1.94% ( 0.037) and 2.09% ( 0.044) per day-degree and mean life expectancy of 51.5 and 47.9 day-degrees above a threshold of 11 C, at the two farms studied. Mean lifetime reproductive output in the field was estimated to be 159.6 and 138.4 eggs per female at the two farms respectively. 4. The survivorship of cohorts of marked female flies in cages was followed by counting the number of dead individuals each day; the mortality rate of these flies was 0.81% per day-degree ( 3.49 10,4%) and the mean life expectancy was 123.1 day-degrees above a threshold of 11 C. Mortality rate was shown to increase significantly with average ambient temperature and relative humidity lagged for two sample periods (approximately 10 days). Oviposition rate also increased with average temperature but declined with average relative humidity. A best-fit multiple regression model incorporating both ambient temperature and humidity explained 60.5% of the variance in the pattern of oviposition. 5. The differences between the field and cage populations highlight the caution required when extrapolating life-history parameters from artificial to natural habitats. [source]


Oviposition decreased in response to enriched water: a field study of the pitcher-plant mosquito, Wyeomyia smithii

ECOLOGICAL ENTOMOLOGY, Issue 1 2007
DAVID HOEKMAN
Abstract 1.,Environmental cues are known to influence oviposition behaviour in mosquitoes, with important consequences for larval survival and insect population dynamics. Enriched microhabitats have been shown to be preferred oviposition sites. 2.,In a field experiment designed to determine whether ovipositing mosquitoes are sensitive to different levels of nutrient enrichment, new pitcher-plant (Sarracenia purpurea) leaves were opened and enriched with 0, 2, or 20 dead ants, and the number of pitcher-plant mosquito (Wyeomyia smithii) larvae resulting from subsequent oviposition were measured. 3.,Oviposition rates were higher in leaves with low levels of enrichment (0 and 2 ants per leaf), although larval development was enhanced at the highest enrichment level. 4.,Results suggest that, although these mosquito larvae are nutrient limited, ovipositing females preferentially avoid highly enriched leaves. This counterintuitive result may be due to low oxygen concentrations or a masked cue in enriched leaves, and contrasts with other oviposition studies. [source]


Factors influencing the seasonal life history of the pitcher-plant mosquito, Wyeomyia smithii

ECOLOGICAL ENTOMOLOGY, Issue 2 2005
Alan O. Bergland
Abstract., 1.,The effects of resource levels, thermal microclimate, and seasonal oviposition patterns on fecundity and survivorship in the pitcher-plant mosquito, Wyeomyia smithii (Coq.), were examined at a northern Wisconsin bog over the course of 2 years. Wyeomyia smithii are bivoltine at this locality, thereby enabling the study of summer and overwintering generations separately. 2.,Nutrient resources of W. smithii were not limiting and there was no indication of density-dependent survivorship or fecundity. 3.,Oviposition rates were highest in young, large pitchers and individual mosquitoes appeared to allocate only a few eggs to any one leaf. 4.,Winter was the harsh season, and the principal manifestation of seasonal harshness was reduced survivorship. 5.,Overwintering W. smithii that had been oviposited later in the summer had a higher odds of survival than those oviposited earlier in the summer. 6.,It was concluded that dispersal of eggs among many pitchers serves to spread the risk of encountering lethal winter temperatures among spatially unpredictable patches. [source]


Effect of temperature on development, overwintering and establishment potential of Franklinothrips vespiformis in the UK

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2007
Eleni Larentzaki
Abstract This study investigated the effect of temperature on the development and overwintering potential of the predatory thrips Franklinothrips vespiformis (Crawford) (Thysanoptera: Aeolothripidae), a biological control agent used against glasshouse pests in continental Europe and Israel. Developmental rates increased linearly with rearing temperatures. It was estimated that 304.9 degree days, above a lower threshold temperature of 11.9 C, were required for F. vespiformis to complete development from egg to adult eclosion. The effect of low temperatures (,5, 0, and 5 C) was examined on adult female and larval survival. Subsequent reproductive and developmental attributes of survivors were also investigated. Lethal time experiments indicated that larval stages are more cold tolerant than adult F. vespiformis females. Surviving larvae increased their developmental times to adults with decreasing temperature and increasing exposure periods and second instars were significantly more successful than first instars in reaching adulthood. Surviving adult females decreased their oviposition rate with decreasing temperature and increasing exposure periods, and exposures to low temperatures affected the number of viable eggs produced. The results are discussed in the context of overwintering and establishment potential of F. vespiformis in the UK in the event of introducing the predatory thrips as a biological control agent against glasshouse pests. [source]


Reproductive responses to photoperiod and temperature by artificially hibernated bumblebee (Bombus terrestris) queens

ENTOMOLOGICAL RESEARCH, Issue 4 2008
Md. Ruhul AMIN
Abstract Post-hibernated bumblebee (Bombus terrestris) queens were kept for 1 week under photoperiodic conditions of 8 h light : 16 h dark, and at four different temperatures (24, 28, 32 and 36C). The reproductive performance of the queens was then observed. It was found that exposure temperature and hibernation duration did not affect the oviposition rate. The pre-oviposition period was found to be shortest (3.8 0.7 days) for queens that had hibernated for 4.0 months and had been activated at 28C. Timing of the initiation of the switch-point was not affected by exposure temperature and hibernation duration. Significantly higher numbers of workers (268.0 31.4) and sexual queens (119.3 16.8) were produced by the queens that had hibernated for 3.0 months and had been activated at 28 and 36C, respectively. The queens that had hibernated for 4.0 months and had been activated at 36C produced the highest number of males (296.2 32.3). [source]


SEASONAL PERFORMANCE AFFECTING POPULATION DYNAMICS OF CITRUS RED MITE, FANONYCHUS CITRI (MCGREGOR) (ACARI: TETRANYCHIDAE), ON PEAR

INSECT SCIENCE, Issue 1 2002
ZHENG Bo-yi
Abstract The population of the citrus red mite, Panonychus citri (McGregor), does not increase on pear from spring to mid-summer but thereafter increases abruptly. To elucidate this phenomenon, we compared the performance of the mites on pear leaves with that on citrus leaves, at different time throughout the pear-growing season. No significant difference was detected between the oviposition rate on pear and that on citrus throughout the season. However, the survival rate of ovipositing females that had fed on pear and the hatch rate of eggs laid by those females were significantly lower than those for females that had fed on citrus, until August. However, no significant difference was observed thereafter. The results showed that the decline of the population of citrus red mite before autumn is due to the high mortality of adult females that had fed on pear leaves and the low hatch rate of the eggs produced by those females. [source]


Floral resources impact longevity and oviposition rate of a parasitoid in the field

JOURNAL OF ANIMAL ECOLOGY, Issue 3 2008
Jana C. Lee
Summary 1The use of floral resource subsidies to improve herbivore suppression by parasitoids requires certain trophic interactions and physiological changes to occur. While the longevity and fecundity of parasitoids are positively affected by nectar subsidies in laboratory studies, the impacts of floral subsidies on the fecundity and longevity of freely foraging parasitoids have not been studied. 2We studied the longevity and per capita fecundity of naturally occurring Diadegma insulare foraging in cabbage plots with and without borders of flowering buckwheat, Fagopyrum esculentum, as well as relationships between longevity, fecundity, sugar feeding and parasitism rates on larvae of the diamondback moth, Plutella xylostella. 3Relative longevity was estimated by counting broken setae on the fringe of the forewing. Floral borders increased the longevity of males and females in adjacent cabbage plots. 4The egg maturation rate of D. insulare was estimated by comparing egg loads of females collected early in the day with egg loads of females held without hosts in field cages throughout the day. Females in buckwheat cages matured 27 eggs per hour while females in control cages resorbed 027 eggs over the same time period. 5The fecundity of females collected in the afternoon was estimated by comparing their actual egg load to the estimated egg load in the absence of oviposition for females in a given plot. Females foraging in buckwheat plots had marginally fewer eggs remaining in their ovaries, and laid marginally more eggs than females in control plots. Females from both treatments carried 30,60 eggs by the afternoon and therefore were time-limited rather than egg-limited. 6Plots where a greater proportion of females had fed on sugar had longer-lived females. This suggests that feeding enhanced longevity of D. insulare. However, plots with longer-lived and more fecund females did not exhibit higher parasitism rates, although the power of these tests were low. [source]


Eggload dynamics and oviposition rate in a wild population of a parasitic wasp

JOURNAL OF ANIMAL ECOLOGY, Issue 2 2000
Jrme Casas
Summary 1.,This paper develops and tests in the field a model that predicts the oviposition rate and the rate of egg maturation of a synovigenic parasitic wasp during a foraging period. The parasitoid is Aphytis melinus, the highly successful biological control agent of California redscale (Aondiniella aurantii), a pest of citrus worldwide. 2.,Females were sampled in the interior canopy of grapefruit trees either just before and at the end of the foraging period over 2 days and were dissected to determine the starting and ending eggload distributions. A group of females was caught before the onset of activity and kept in vials in the field in trees with honey but without access to hosts during the foraging period. Their eggload at the end of the day was used to estimate the egg maturation rate during the foraging period. 3.,Two stochastic models are used to predict the eggload distribution at the end of the day. Both use the observed starting eggload distribution, the observed length of the foraging period and the estimated rate of egg maturation. The model providing the better fit uses an oviposition rate which is an increasing function of the eggload. 4.,The eggload does not attain a steady state distribution during a foraging period. One-third to one-half of the population is predicted to experience egg-limitation at some time during the foraging period. Five percent of the population will experience egg-limitation a second time within a single day. 5.,The common occurrence of egg-limitation over a single day and the relatively high rate of change of states between egg- and time-limitation imply that the rate of nutrient acquisition and use are likely to be subject to strong evolutionary pressures. [source]


Adult mortality and oviposition rates in field and captive populations of the blowfly Lucilia sericata

ECOLOGICAL ENTOMOLOGY, Issue 6 2004
K. M. Pitts
Abstract., 1. Adult mortality and oviposition rates were determined for populations of the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae). This species is of economic importance as the primary agent of sheep myiasis throughout north-western Europe. 2. Populations of marked flies in six, 1 m3, outdoor field cages and unmarked wild flies at two farms in south-west England were studied simultaneously between May and September 1998. 3. In the field, wild female L. sericata were caught and aged using a combination of wing-fray and ovarian dissection techniques. Survivorship analysis gave estimates of mortality of 1.94% ( 0.037) and 2.09% ( 0.044) per day-degree and mean life expectancy of 51.5 and 47.9 day-degrees above a threshold of 11 C, at the two farms studied. Mean lifetime reproductive output in the field was estimated to be 159.6 and 138.4 eggs per female at the two farms respectively. 4. The survivorship of cohorts of marked female flies in cages was followed by counting the number of dead individuals each day; the mortality rate of these flies was 0.81% per day-degree ( 3.49 10,4%) and the mean life expectancy was 123.1 day-degrees above a threshold of 11 C. Mortality rate was shown to increase significantly with average ambient temperature and relative humidity lagged for two sample periods (approximately 10 days). Oviposition rate also increased with average temperature but declined with average relative humidity. A best-fit multiple regression model incorporating both ambient temperature and humidity explained 60.5% of the variance in the pattern of oviposition. 5. The differences between the field and cage populations highlight the caution required when extrapolating life-history parameters from artificial to natural habitats. [source]


Effects of infection of the tick Ornithodoros moubata with African swine fever virus

MEDICAL AND VETERINARY ENTOMOLOGY, Issue 4 2000
L. Rennie
Summary The effects of infection with African swine fever virus (ASFV) on adult and nymphal Ornithodoros moubata Murray (Ixodoidea, Argasidae) ticks were examined. Three groups of ticks were used, an uninfected control group, one group infected with the VIC T90/1 isolate of ASFV and another group infected with the LIV 13/33 isolate of ASFV. Infection with ASFV did not affect the oviposition rates of infected ticks when compared with uninfected ticks. There was no difference between infected and uninfected ticks in progeny hatching rates and first nymphal stage feeding rates. Feeding rates of infected adult ticks were also unaffected. However, a significant increase in mortality rates was observed amongst the adult ticks that fed on an infective bloodmeal compared to ticks fed on an unifected bloodmeal. [source]