SIMULATION MODEL FOR THE POPULATION DYNAMICS OF THE CARROT WEEVIL, LISTRONOTUS OREGONENSIS (LECONTE) (COLEOPTERA: CURCULIONIDAE)

1991 ◽  
Vol 123 (1) ◽  
pp. 63-76 ◽  
Author(s):  
D.X. Zhao ◽  
G. Boivin ◽  
R.K. Stewart
Keyword(s):  
Population Dynamics ◽  
Simulation Model ◽  
Mortality Rates ◽  
Egg Parasitoid ◽  
Adult Density ◽  
Larval Population ◽  
Listronotus Oregonensis ◽  
The Mean ◽  
Carrot Weevil ◽  
The Impact

AbstractA simulation model was developed for the population dynamics of a carrot weevil, Listronotus oregonensis (LeConte), population on muck-grown carrots. The model includes mortality rates of eggs, larvae, and pupae for different sowing dates of carrots. It also incorporates the overwintered adult density, the temperature-dependent growth rates of the above-mentioned life stages, the age-, temperature-, and phenology-dependent oviposition rates, and the impact of an egg parasitoid, Anaphes sordidatus (Girault), on egg mortality rates. Model output was evaluated by comparing simulated results with observed results on the seasonal totals and time of population peaks of the egg and larval populations. The mean percentage differences between the simulated and observed seasonal egg totals were 3.1 ± 0.66 (SE) in 1987 and 1988, and 4.2 ± 0.05 in 1989. They were not statistically different. The mean percentage differences between the simulated and observed seasonal larval totals were 10 ± 3.33 in 1987 and 1988 and 29.8 ± 0.66 in 1989. Independent data sets (i.e. field data in 1989) showed a significant increase in the simulation error of the larval population. Sensitivity analysis indicated that A. sordidatus had a large influence on the population dynamics of L. oregonensis.

Cycle de développement, croissance et production de Pisidium amnicum (Mollusca: Bivalvia) dans le Saint-Laurent (Québec)

1981 ◽  
Vol 59 (12) ◽  
pp. 2350-2359 ◽  
Author(s):  
B. Vincent ◽  
G. Vaillancourt ◽  
N. Lafontaine
Keyword(s):  
Population Dynamics ◽  
Sexual Maturity ◽  
Dry Weight ◽  
Mortality Rates ◽  
The Other ◽  
Annual Production ◽  
Bithynia Tentaculata ◽  
The Mean ◽  
Total Dry Weight ◽  
St Lawrence River

The population dynamics of Pisidium amnicum have been studied in one population of the St. Lawrence River over a 2-year period during which 19 samples were taken. The species can live up to 3 years and it is iteroparous; individuals generally attain sexual maturity after 1 year and they reproduce twice, once at 2 and once at 3 years of age. In adults, mortality is lower in winter than during the rest of the year and mortality rates are twice as high during the 1st year than during the 2nd year. Total dry weight (PT, in milligrams) is related to maximum length (L, in millimetres) according to the equation PT = 0.0283∙L3,80 and flesh dry weight (PC, in milligrams) is related to length as follows: PC = 0.007∙L3,18. The annual production to mean biomass (P/B) ratio is 1.4, the mean annual production being 1.298 mg/m2 of total dry weight and 107 mg/m2 of flesh weight. Comparing these results with those obtained for the gastropod Bithynia tentaculata in the same environment and at the same period of the year has shown that the growth of Pisidium amnicum is far less influenced by the temperature regime than that of the other species and that its production is at least 10 times lower.

UnexpectedListronotus bonariensis(Coleoptera: Curculionidae) mortality in the presence of parasitoids

2004 ◽  
Vol 94 (5) ◽  
pp. 411-417 ◽  
Author(s):  
S.L. Goldson ◽  
J.R. Proffitt ◽  
M.R. McNeill ◽  
C.B. Phillips ◽  
N.D. Barlow ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Mortality Rates ◽  
Ecological Significance ◽  
Time Intervals ◽  
Larval Parasitoid ◽  
Mortality Effect ◽  
Listronotus Bonariensis ◽  
Field And Laboratory Conditions ◽  
The Impact ◽  
Microctonus Hyperodae

AbstractField enclosure and laboratory cage experiments designed to measure the impact of the parasitoidMicroctonus hyperodaeLoan on the Argentine stem weevil,Listronotus bonariensis(Kuschel) have shown that under high parasitoid pressure, there is significant weevil mortality without obvious parasitism. Parasitoid-exposed, but unparasitized portions of caged populations died at rates significantly higher than both the parasitized weevils from the same population and the unexposed controls. Unexpectedly, parasitized weevils had the lowest mortality rates (prior to larval parasitoid emergence). It was of ecological significance that this mortality effect was detected under field conditions using several years of empirically-collected population dynamics data. Under both field and laboratory conditions this mortality was found to occur within shorter time intervals than that required for full parasitoid larval development; thus it could not be attributed to the mortality that occurs after the emergence of prepupal parasitoids. The mechanism for this mortality remains undetermined, although it could possibly be linked to pseudoparasitism.

IMPACT OF BEAUVERIA BASSIANA ON THE COTTONWOOD BORER, PLECTRODERA SCALATOR (COLEOPTERA: CERAMBYCIDAE), IN A COMMERCIAL COTTONWOOD NURSERY.

1989 ◽  
Vol 24 (2) ◽  
pp. 186-190 ◽  
Author(s):  
B. T. Forschler ◽  
G. L. Nordin
Keyword(s):  
Beauveria Bassiana ◽  
Populus Deltoides ◽  
Adult Population ◽  
Control Treatment ◽  
High Dose ◽  
Flight Period ◽  
Treatment Area ◽  
Larval Population ◽  
The Mean ◽  
The Impact

A commercial Beauveria bassiana (Balsamo) Vuillemin conidial formulation, AGB 6178, was applied as a soil drench against the cottonwood borer, Plectrodera scalator (F.), in a commercial eastern cottonwood, Populus deltoides, nursery. Doses of 0, 2 × 109, 2 × 1010 and 1 × 1011 conidia/m2 were applied in June 1986. The adult population was monitored throughout its flight period (June–August) for B. bassiana infection. Greater than 60% of the adults collected in the treatment area post-treatment were infected with B. bassiana. The impact of the fungal application on the larval population was assessed 8 months later by the removal and dissection of the treated rootstocks. Though no differences were detected in the number of second-year larvae recovered, the mean number of first-year larvae found at the high dose (1 × 1011 CFU's/m2) was significantly less (LSD, alpha 0.05) than the mean number of larvae found in the control treatment (0 CFU's/m2), 5.0 and 9.4 larvae/10 rootstocks, respectively.

Impact of mortality, possibly due to herpesvirus, on pilchard Sardinops sagax stocks along the south coast of Western Australia in 1998-99

2000 ◽  
Vol 51 (6) ◽  
pp. 601 ◽  
Author(s):  
D. J. Gaughan ◽  
R. W. Mitchell ◽  
S. J. Blight
Keyword(s):  
Western Australia ◽  
Total Mortality ◽  
Simulation Models ◽  
Mortality Rates ◽  
Sea Surface ◽  
Sea Floor ◽  
Wide Range ◽  
The Mean ◽  
The Difference ◽  
The Impact

During progression of a mass mortality of Australian pilchards in late 1998 and early 1999, quantities of dead pilchards on the sea-surface, sea-floor and along beaches were estimated in three regions along southern Western Australia (WA) by use of transects. Total mortality was estimated at 17 590, 11193 and 144.4 t for Esperance, Bremer Bay and Albany respectively. Mortality rates at Esperance and Bremer Bay were similar at 74.5% and 64.7% respectively, with a mean of 69.6%. In contrast, estimated mortality at Albany was only 2.4%. Although the difference in total mortality between regions is probably related to differences in stock size, as determined by simulation models, the much lower estimate for Albany is probably an artefact of an over-estimated pilchard biomass and not due to large differences in actual mortality rates. Variability in estimates of both pilchard biomass and quantities killed resulted in a wide range of estimated mortality rates, with lower estimates for Esperance and Bremer Bay of 28.0% and 22.9% respectively. This represents a significant decline in the breeding stock of WA pilchards. If the impact was closer to the mean (69.6%), then pilchard stocks in WA are severely depressed.

Investigation of the Impact of Mercury on Enclosed Water Columns Using a Zooplankton Simulation Model

1977 ◽  
Vol 34 (12) ◽  
pp. 2295-2307 ◽  
Author(s):  
Nicholas C. Sonntag ◽  
Wulf Greve
Keyword(s):  
Population Dynamics ◽  
Simulation Model ◽  
Direct Consequence ◽  
Oncorhynchus Keta ◽  
Computer Simulation Model ◽  
Real World Data ◽  
Water Columns ◽  
Age Dependent ◽  
Zooplankton Dynamics ◽  
The Impact

A computer simulation model of a phytoplankton–zooplankton–salmon system is used to investigate possible causes of different Pseudocalanus minutus s.l. population dynamics in three enclosed water columns. Mercury at 1 and 5 μg/ℓ was added to two enclosures, with the third serving as a control. Represented in the model are diatoms, flagellates, P. minutus, and fingerling chum salmon (Oncorhynchus keta). Population dynamics are represented in terms of age structure, with age-dependent feeding and survival. Real world data are used to represent the phytoplankton densities. The model results support a hypothesis that the observed Pseudocalanus populations after day 25 could have been a direct consequence of different flagellate populations in the enclosures rather than lethal effects of mercury on molting and reproduction success of the copepod. Key words: modeling, simulation, controlled ecosystems, mercury, zooplankton dynamics

scholarly journals Prevalence of a nematode castrator of the carrot weevil and impact on fecundity and survival

Parasitology ◽  
2018 ◽  
Vol 146 (6) ◽  
pp. 702-707 ◽  
Author(s):  
Annie-Ève Gagnon ◽  
Guy Boivin ◽  
Guy Bélair ◽  
Benjamin Mimee
Keyword(s):  
Parasitic Nematode ◽  
Life Stages ◽  
Hormone Production ◽  
Infected Female ◽  
Parasitic Castration ◽  
Important Pest ◽  
Listronotus Oregonensis ◽  
Carrot Weevil ◽  
The Impact ◽  
Unique Potential

AbstractBradynema listronoti is a parasitic nematode described from infected specimens of the carrot weevil Listronotus oregonensis. Prevalence of infection by B. listronoti under field conditions was followed over a period of 16 years in an untreated carrot field. Susceptibility of different carrot weevil life stages was evaluated as well as the impact of infection on fecundity and mortality. Gene expression in infected and uninfected carrot weevils was also compared to evaluate the impact of the parasite on the host transcriptome. Prevalence of B. listronoti in carrot weevil populations was sustained over the years ranging from 20 to 63%. All the weevil stages exposed to B. listronoti inoculum were susceptible to infection, larvae being more vulnerable (59 ± 8% infected) compared with pupae (4 ± 3% infected) and adults (7 ± 3% infected). The fecundity of infected female weevils was greatly reduced (60-fold) due to an inhibition of the maturation of the reproductive system. Transcriptomic analyses revealed that this parasitic castration may have been triggered by the inhibition of reproductive hormone production. The B. listronoti–L. oregonensis interaction represents a case of parasitic castration with a unique potential for biological control of an important pest of carrots.

L'enneigement hivernal : un facteur de variation du recrutement chez l'isard (Rupicapra pyrenaica pyrenaica)

2002 ◽  
Vol 80 (7) ◽  
pp. 1306-1312 ◽  
Author(s):  
J -P Crampe ◽  
J -M Gaillard ◽  
A Loison
Keyword(s):  
Population Dynamics ◽  
Climatic Conditions ◽  
Snow Accumulation ◽  
Yearly Variation ◽  
Rupicapra Pyrenaica ◽  
Winter Snow ◽  
Population Recruitment ◽  
The Mean ◽  
Mountain Ungulates ◽  
The Impact

To assess the relationships between winter climatic conditions and population dynamics of mountain ungulates, we monitored over the long term an unhunted isard (Rupicapra pyrenaica pyrenaica) population living in the Pyrénées National Park. We used general linear modelling to assess (i) the influence of the observation date (between November and April) of the transect sampled and of the year on population recruitment (proportion of females 2 years of age and older with kids at heel) and (ii) the impact of snow accumulation during winter (cumulated snow fall from November to April) on kid mortality. As expected, the mean number of kids per female decreased over the observation period. The mean number of kids per female showed marked among-year differences in initial recruitment (measured on 31 October) as well as in kid mortality (measured as the decrease in recruitment between 31 October and 31 March). This model accounted for 80% of the variability observed in the field data. Among-year differences in snow accumulation accounted for most (86%) of the yearly variation observed in kid mortality. Our study demonstrates that winter snow may severely affect juvenile survival, and thereby population dynamics of mountain ungulates.

Relationship between carrot weevil (Coleoptera: Curculionidae) infestation, damage, and planting dates of parsley (Apiaceae)

2002 ◽  
Vol 134 (1) ◽  
pp. 125-135 ◽  
Author(s):  
Angel N. Torres ◽  
Casey W. Hoy
Keyword(s):  
Control Measures ◽  
Petroselinum Crispum ◽  
Initial Population ◽  
Life Stages ◽  
Seasonal Activity ◽  
Planting Dates ◽  
Listronotus Oregonensis ◽  
Carrot Weevil ◽  
The Impact ◽  
Root Feeding

AbstractSeasonal activity of carrot weevil, Listronotus oregonensis (LeConte), adults, eggs, larvae, and root feeding was studied in plots of parsley, Petroselinum crispum (Mill.) Nyman ex A.W. Hill, by sampling weekly from mid-May to the first week of September in 1998 and 1999. The initial population of overwintering adults, one complete generation, and at least a partial second generation were observed. The majority of eggs were deposited in June and most of the larvae were counted in July; the greatest damage was noticed from July onward. In both 1998 and 1999, the overall seasonal means of adults, eggs, larvae, and root feeding were significantly different among plots that were planted on different dates. Root feeding and all carrot weevil life stages sampled steadily decreased from the earliest to the latest planting. Most of the damage occurred in parsley plantings sown from late February until the third week of April. The number of eggs removed from parsley plants during the first cutting was significantly different among planting dates, but the impact of this removal may not be significant in infestation reduction. Results of this study will help parsley growers to target when control measures for carrot weevil will be most effective and which plantings are most likely to be damaged.

The importance of temperature and lipid accumulation for initiation and duration of Calanus hyperboreus spawning

2020 ◽  
Vol 42 (2) ◽  
pp. 159-171
Author(s):  
Mads Schultz ◽  
Torkel Gissel Nielsen ◽  
Eva Friis Møller
Keyword(s):  
Population Dynamics ◽  
Lipid Metabolism ◽  
Lipid Content ◽  
Egg Production ◽  
Arctic Ecosystems ◽  
Calanus Hyperboreus ◽  
Higher Temperature ◽  
The Mean ◽  
Increasing Temperature ◽  
The Impact

Abstract Large, lipid-storing copepods play a central role in marine Arctic ecosystems. Knowledge of the mechanisms that control their oogenesis is important for understanding their phenology and population dynamics. We investigated the impact of female lipid content on the timing and cumulative egg production (EP) of Calanus hyperboreus at 0, 3 and 6°C. The lipid content of females in early autumn was a good predictor of their EP potential. However, we saw no indication of a threshold in lipid content for initiation of spawning. Higher temperature resulted in 17 and 24 days earlier spawning at 3 and 6°C compared with 0°C, and the mean spawning duration was 8 and 30 days shorter, respectively. This illustrates that temperature affects the phenology of C. hyperboreus. When EP began, lipid metabolism increased 2–4 times. The females allocated 1.3 μg lipid per egg independent of temperature. However, the basic metabolism increased with increasing temperature; consequently, a smaller fraction of lipid was allocated for EP when the temperature increased.

scholarly journals The detection of Anaphes sp. nov. [Hymenoptera : Mymaridae], an egg parasitoid of the carrot weevil in Nova Scotia

2005 ◽  
Vol 77 (2) ◽  
pp. 79-82 ◽  
Author(s):  
L.R.E. Hopper ◽  
J.-P.R. Le Blanc ◽  
G. Boivin
Keyword(s):  
Nova Scotia ◽  
Parasitic Wasp ◽  
Egg Parasitoid ◽  
Width Ratio ◽  
Length Width ◽  
Listronotus Oregonensis ◽  
Growth Chambers ◽  
Carrot Weevil ◽  
Anaphes Listronoti ◽  
A New Species

The wasps Anaphes victus (Huber) and Anaphes listronoti (Huber) [Hymenoptera : Mymaridae] parasitize 50% of the eggs of carrot weevil, Listronotus oregonensis (Le Conte) [Coleoptera : Curculionidae] in Quebec and in Ontario. Attempts to detect either of these egg parasites from exposed carrot weevil eggs in Nova Scotia were unsuccessful. However, 48 individuals of a new species of parasitic wasp, Anaphes sp. nov. [Hymenoptera : Mymaridae], were detected in carrot (Daucus carota) fields in Nova Scotia, using carrots infested in growth chambers with carrot weevil eggs. Anaphes sp. nov. is distinguishable from the other parasites of the carrot weevil by characteristics of the forewing. Anaphes sp. nov. has a forewing length : width ratio greater than 7 :3 while A. victus and A. listronoti have a forewing length : width ratio of less than 6 : 7.

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