Life history and abundance of the predaceous psammophilous mayfly Pseudiron centralis McDunnough (Ephemeroptera: Heptageniidae)

1984 ◽  
Vol 62 (8) ◽  
pp. 1534-1539 ◽  
Author(s):  
Daniel A. Soluk ◽  
Hugh F. Clifford
Keyword(s):  
Life History ◽  
Larval Mortality ◽  
Larval Density ◽  
Dry Weight ◽  
Minimum Size ◽  
Dispersion Pattern ◽  
Chironomid Larvae ◽  
Short Period ◽  
Growth Method ◽  
Shifting Sand

Aspects of the life history and abundance of Pseudiron centralis McDunnough were examined in the Sand River in east central Alberta. The population exhibited a univoltine summer life cycle, spending 9 to 10 months of the year in the egg stage. Eggs were large (0.33 × 0.41 mm; mean dry weight, 0.005 mg). Larvae were associated with three types of substrate in the river bed: shifting sand, marginal sand, and gravelly sand. Larvae were active epibenthic predators, feeding primarily on psammophilous chironomid larvae. Larval density was low (< 4 larvae/m2); however, larval mortality also appeared to be low. Stage III and IV larvae exhibited a random dispersion pattern. Annual production (instantaneous growth method) was estimated to be 28.70 and 11.24 mg∙m−2∙year−1 in 1980 and 1981, respectively. The relatively large size of first-instar larvae may allow them to cope with the dynamics of sandy substrates, or may be the minimum size that can effectively capture and consume chironomid larvae. Although chironomid abundance in sandy substrates remains high throughout the year, P. centralis larvae exploit this resource for only a short period.

Laboratory culture of Dreissena polymorpha larvae: spawning success, adult fecundity, and larval mortality patterns

2004 ◽  
Vol 82 (9) ◽  
pp. 1436-1443 ◽  
Author(s):  
James A Stoeckel ◽  
Dianna K Padilla ◽  
Daniel W Schneider ◽  
Chris R Rehmann
Keyword(s):  
Life History ◽  
Dreissena Polymorpha ◽  
Egg Production ◽  
Larval Mortality ◽  
Field Studies ◽  
Laboratory Culture ◽  
Minimum Size ◽  
Critical Periods ◽  
Brood Stock ◽  
Wide Range

Understanding the entire life history, especially critical periods during the life cycle of a species, is important for understanding population dynamics and is crucial for control of nuisance species. Errors in estimates of growth rates and recruitment in field and modeling studies are likely to occur if one assumes uniform rather than size- or stage-specific mortalities for larval stages. Similarly, effects of brood-stock health on adult fecundity and larval mortality patterns might affect results of laboratory studies investigating larval life history. We maintained zebra mussels, Dreissena polymorpha (Pallas, 1771), in spawning condition in the laboratory for 24 weeks. Healthy larvae were produced for 18 weeks. However, induction of spawning and egg production declined through time. Fecundity increased with size per female, but sperm production did not for males. We found no correlation between clutch size and egg size across a wide range of clutch sizes. Survivorship was greater when larvae were reared at lower densities. Daily larval mortality was strongly size dependent; the average size of dead larvae was similar to the minimum size of live larvae. Highest daily larval mortality occurred during the transition from D stage to umbonal stage, supporting the suggestion of a developmental bottleneck as found in previous field studies.

scholarly journals Larval density, temperature and biological aspects of Chrysomya megacephala (Diptera: Calliphoridae)

2006 ◽  
Vol 58 (4) ◽  
pp. 562-566 ◽  
Author(s):  
C. Reigada ◽  
W.A.C. Godoy
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Body Size ◽  
Larval Density ◽  
Chrysomya Megacephala ◽  
Life History Characteristics ◽  
Two Temperatures ◽  
Biological Aspects ◽  
Experimental Populations ◽  
Simultaneous Influence

The effect of larval density on the survival, fecundity and body size at two temperatures in experimental populations of C. megacephala was studied. No effect from simultaneous influence of density and temperature on life history characteristics of C. megacephala was found. Significant effects of density and temperature on survival, fecundity and body size were observed. The importance of these results for the population dynamics of C. megacephala is discussed.

scholarly journals Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model

2016 ◽  
Author(s):  
Eric G Johnson ◽  
Mary Katherine Swenarton
Keyword(s):  
Population Structure ◽  
Life History ◽  
Control Strategies ◽  
Ecological Impacts ◽  
Pterois Volitans ◽  
Structured Population Model ◽  
Western Atlantic ◽  
Short Period ◽  
Age Structured ◽  
Negative Impacts

The effective management of invasive species requires a detailed understanding of the invader’s life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish ( Pterois volitans/miles ) have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1) lionfish exhibited rapid growth with seasonal variation in growth rates, (2) distinct cohorts were clearly identifiable in the length-frequency data suggesting that lionfish arerecruiting during a relatively short period in summer, and (3) the majority of lionfish were less than two years old with no lionfish older than 3 years of age, possibly as a result of an ontogenetic shift to deeper water, which may provide a reservoir of spawning biomass not accessible to recreational or commercial spearfishing.

INFLUENCE OF FOLIAR NITROGEN LEVELS ON SURVIVAL, DEVELOPMENT, AND REPRODUCTION OF WESTERN SPRUCE BUDWORM, CHORISTONEURA OCCIDENTALS (LEPIDOPTERA: TORTRICIDAE)

1985 ◽  
Vol 117 (1) ◽  
pp. 23-32 ◽  
Author(s):  
J. Wayne Brewer ◽  
John L. Capinera ◽  
Robert E. Deshon ◽  
Mary L. Walmsley
Keyword(s):  
Larval Mortality ◽  
Spruce Budworm ◽  
Dry Weight ◽  
Douglas Fir ◽  
Nitrogen Level ◽  
Pupal Weight ◽  
Western Spruce Budworm ◽  
Foliar Nitrogen ◽  
Nitrogen Levels ◽  
White Fir

AbstractThe influence of nitrogen levels in foliage of white-fir, Abies concolor, and Douglas-fir, Pseudotsuga menziesii, seedlings on various biological characteristics of the western spruce budworm, Choristoneura occidentalis Freeman, was studied. Seedlings were grown under greenhouse conditions and provided with nutrient solutions to maintain five foliar nitrogen levels ranging from 1.29 to 4.42% dry weight for white fir and 1.43 to 3.94% for Douglas fir. Larvae confined to treated seedlings were monitored through the next generation. Larval mortality was higher, and development time longer, at both upper and lower extremes of foliar nitrogen than at mid-level. Mean pupal weight was significantly greater for larvae reared on white fir with the mid-range foliar-nitrogen level. Mean number, and weight, of eggs laid were highest when larvae fed on foliage from the mid-range nitrogen level. Total number of larvae produced was lowest at the high and low extremes of foliar nitrogen levels.

Colonization patterns and life-history dynamics of Culex mosquitoes in artificial ponds of different character

1993 ◽  
Vol 71 (3) ◽  
pp. 568-578 ◽  
Author(s):  
D. Dudley Williams ◽  
Annette Tavares-Cromar ◽  
Donn J. Kushner ◽  
John R. Coleman
Keyword(s):  
Life History ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Larval Development ◽  
Development Time ◽  
Larval Density ◽  
Strong Relationship ◽  
Terrestrial Vegetation ◽  
Widespread Species ◽  
Artificial Ponds

The relationship between the biology and habitat of larval mosquitoes was studied in a series of artificial ponds of differing characteristics established across a terrestrial vegetation gradient from open fields to deep woods. The ponds were uniformly colonized by two widespread species of Culex, both characteristic of small bodies of water, including artificial, "container" habitats. First-instar larvae of Culex restuans were found within 2 days of filling the ponds with water and four or five generations were produced from May until the end of September. One very long generation occurred in July, which corresponded to maximum larval densities. Overall, there was a strong relationship between larval development time of C. restuans and larval density. A few larvae of Culex pipiens pipiens occurred sporadically throughout the summer, but numbers did not increase until C. restuans populations began to wane in late July. Thereafter two, or possibly three, generations were produced into the autumn. The patterns of colonization, synchrony of life history, and growth of these two species were remarkably consistent amongst the ponds, despite considerable variation in both their physical and biological environments (e.g., over the 2 years of study, conductivity ranged from 20 to 890 μS, pH from 6.4 to 10.7, dissolved oxygen from 0 to 13.5 ppm, and water temperature from 5 to 29.8 °C). Density of C. restuans was related to water temperature and pH at the "open" site and to water temperature, dissolved oxygen, percent algae, and percent detritus at the "edge of the woods" site. At the "deep woods" site, larval numbers were related to temperature, pH, conductivity, and dissolved oxygen. At both the edge and deep wood sites, larval development time of C. restuans increased with mean water temperature to 20 °C. Above this temperature, larval development time tended to decrease.

scholarly journals Effectiveness of Diflubenzuron and Bacillus thuringiensis Against Gypsy Moth Populations

1997 ◽  
Vol 14 (3) ◽  
pp. 135-140 ◽  
Author(s):  
Kevin W. Thorpe ◽  
Richard L. Ridgway ◽  
Ralph E. Webb
Keyword(s):  
Bacillus Thuringiensis ◽  
Population Density ◽  
Gypsy Moth ◽  
Mass Density ◽  
Larval Mortality ◽  
Larval Density ◽  
Egg Mass ◽  
Percent Reduction ◽  
Moth Population ◽  
Oak Trees

Abstract Aerial applications of Bacillus thuringiensis Berliner subsp. kurstaki (74.1 billion international units/ha per application; single and double applications), diflubenzuron [69 g (ai)/ha], and no treatment were evaluated. Treatment effects were estimated from frass collections, defoliation, counts of pupae under burlap, and egg-mass counts. Estimates of larval density in the canopy 20 days after treatment ranged from 318.3 to 55.5 larvae per m² in the control- and diflubenzuron-treated plots, respectively. Larval density was reduced in all treatments, and was lowest in the plots treated with diflubenzuron and two applications of B. thuringiensis. Population density rapidly declined in the control plots, and by June 20, when larvae were predominantly in the fifth and sixth instars, no significant differences in larval density were detected among the treatments. Significantly less defoliation occurred to oak trees in the treated plots, but no differences were detected among the spray treatments. Counts of pupae under burlap, postseason egg-mass counts, and percent reduction in egg-mass density did not differ significantly among treatments or versus controls. These results suggest that diflubenzuron and double B. thuringiensis treatments caused higher levels of larval mortality than occurred with a single B. thuringiensis application, but that with a naturally declining gypsy moth population the final levels of damage were the same under all treatments. North. J. Appl. 14(3):135-140.

INTERPRETATION OF DENSITY DEPENDENT DATA IN COMPARISONS OF BACILLUS THURINGIENSIS VAR. ISRAELENSIS FORMULATIONS1

1988 ◽  
Vol 23 (2) ◽  
pp. 149-154 ◽  
Author(s):  
J. Vorgetts ◽  
Robert L. Frommer ◽  
Paul H. Gibbs ◽  
L. M. Anderson
Keyword(s):  
Bacillus Thuringiensis ◽  
Acute Toxicity ◽  
Larval Mortality ◽  
Larval Density ◽  
Dependent Data ◽  
Water Volume ◽  
Mortality Data ◽  
Absolute Amount ◽  
Wettable Powder ◽  
Standard Powder

The effect of larval density on estimates of effectiveness of larvicides with Bacillus thuringiensis var. israelensis (BTI) as the active ingredient (a.i.) was evaluated. Bioassays with Aedes aegypti (L.) fourth instars showed that the toxic effect of a standard powder (IPS-78) and a wettable powder formulation (Bactimos®) was independent of volume because the effect of varying the water volume in test vessels was usually negligible and had no obvious relationship to larval mortality. Data were best interpreted as a function of dose (i.e., the absolute amount of a. i.) and the number of larvae in each test vessel rather than as a function of concentration (dose rate). This indicated that accurate comparisons of acute toxicity estimates derived from different tests with differing numbers of larvae (i.e., differing densities) can be made if results are reduced to and expressed as the EC50/larva.

Larval intraspecific competition for food in the European grapevine moth Lobesia botrana

2014 ◽  
Vol 104 (4) ◽  
pp. 517-524 ◽  
Author(s):  
D. Thiéry ◽  
K. Monceau ◽  
J. Moreau
Keyword(s):  
Life History ◽  
Intraspecific Competition ◽  
Life History Traits ◽  
Larval Mortality ◽  
Lobesia Botrana ◽  
Reproductive Capacity ◽  
Strong Increase ◽  
European Grapevine Moth ◽  
Grapevine Moth ◽  
Larval Crowding

AbstractEffective pest management with lower amounts of pesticides relies on accurate prediction of insect pest growth rates. Knowledge of the factors governing this trait and the resulting fitness of individuals is thus necessary to refine predictions and make suitable decisions in crop protection. The European grapevine moth, Lobesia botrana, the major pest of grapes in Europe, is responsible for huge economic losses. Larvae very rarely leave the grape bunch on which they were oviposited and thus cannot avoid intraspecific competition. In this study, we determined the impact of intraspecific competition during the larval stage on development and adult fitness in this species. This was tested by rearing different numbers of larvae on an artificial diet and measuring developmental and reproductive life history traits. We found that intraspecific competition during larval development has a slight impact on the fitness of L. botrana. The principal finding of this work is that larval density has little effect on the life history traits of survivors. Thus, the timing of eclosion, duration of subsequent oviposition, fecundity appears to be more uniform in L. botrana than in other species. The main effect of larval crowding was a strong increase of larval mortality at high densities whereas the probability of emergence, sex ratio, pupal mass, fecundity and longevity of mated females were not affected by larval crowding. Owing to increased larval mortality at high larval densities, we hypothesized that mortality of larvae at high densities provided better access to food for the survivors with the result that more food was available per capita and there were no effect on fitness of survivors. From our results, larval crowding alters the reproductive capacity of this pest less than expected but this single factor should now be tested in interaction with limited resources in the wild.

ECONOMIC INJURY LEVELS OF THE ALFALFA WEEVIL (COLEOPTERA: CURCULIONIDAE)

1973 ◽  
Vol 105 (1) ◽  
pp. 61-74 ◽  
Author(s):  
Philip G. Koehler ◽  
David Pimentel
Keyword(s):  
Food Consumption ◽  
Larval Density ◽  
New York State ◽  
Live Weight ◽  
Dry Weight ◽  
Larval Feeding ◽  
Larval Food ◽  
Alfalfa Weevil ◽  
Second Growth ◽  
Economic Injury

AbstractEconomic injury levels of the alfalfa weevil on alfalfa were investigated in New York State. The dry weight food consumption for the larval stage of the alfalfa weevil averaged 7.34 mg/larva. For every gram (dry weight) of alfalfa consumed, 1.59 g (live weight) in insect tissue was produced. In the laboratory, it was found that insect food consumption could account for only about 50% of the total weight loss in alfalfa plants after 10 days of larval feeding. Therefore, alfalfa weevil damage to alfalfa was more than the larval food consumption, and this was believed to be due to the loss of the plant’s photosynthetic potential. In the field on first growth alfalfa, the economic injury level was calculated to be 56 larvae/stem. First growth alfalfa was less severely injured by alfalfa weevil larvae than our second growth alfalfa infested with equal populations of alfalfa weevils. It was shown that first growth alfalfa was able to compensate for 87% of the insect feeding while second growth alfalfa could compensate for only 50%. Since the alfalfa plant’s capacity to compensate for alfalfa weevil feeding can vary due to environmental conditions and plant characteristics, economic injury levels must be adjustable. To provide more reliability to economic injury levels, we propose that in alfalfa the following seven measurements be made: (1) alfalfa weevil larval density; (2 and 3) parasites and predators of the weevil; (4) rainfall and moisture level; (5) plant nutrients; (6) alfalfa variety; and (7) stage and previous management of alfalfa stand.

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