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.

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.

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.

ANAPHES SORDIDATUS (GIRAULT) (HYMENOPTERA: MYMARIDAE), AN EGG PARASITE OF THE CARROT WEEVIL, LISTRONOTUS OREGONENSIS (LE CONTE)

1986 ◽  
Vol 118 (4) ◽  
pp. 393-394 ◽  
Author(s):  
Guy Boivin
Keyword(s):  
Integrated Pest Management ◽  
Pest Management ◽  
Control Methods ◽  
Eastern Canada ◽  
Egg Parasite ◽  
Additional Control ◽  
Important Pest ◽  
Listronotus Oregonensis ◽  
Seeding Time ◽  
Carrot Weevil

The carrot weevil, Listronotus oregonensis (Le Conte), is an important pest of carrot and celery in eastern Canada (Stevenson 1985). In Quebec, it is univoltine and overwinters as adults (Boivin 1985). At present, the only way to control this pest is with chemical insecticides applied either as granules at seeding time to control the larvae or as foliar sprays to control the adults before they start to oviposit. If integrated pest management (IPM) programs are to be applied to crops attacked by the carrot weevil, additional control methods are needed.

scholarly journals MPA network design based on graph theory and emergent properties of larval dispersal

2020 ◽  
Vol 650 ◽  
pp. 309-326
Author(s):  
A Ospina-Alvarez ◽  
S de Juan ◽  
J Alós ◽  
G Basterretxea ◽  
A Alonso-Fernández ◽  
...  
Keyword(s):  
Graph Theory ◽  
Network Design ◽  
Early Life ◽  
Larval Dispersal ◽  
Network Connectivity ◽  
Life Stages ◽  
Early Life Stages ◽  
Larval Connectivity ◽  
The Impact ◽  
Mpa Network

Despite the recognised effectiveness of networks of marine protected areas (MPAs) as a biodiversity conservation instrument, MPA network design frequently disregards the importance of connectivity patterns. In the case of sedentary marine populations, connectivity stems not only from the stochastic nature of the physical environment that affects dispersal of early life stages, but also from the spawning stock attributes that affect reproductive output (e.g. passive eggs and larvae) and survivorship. Early life stages are virtually impossible to track in the ocean. Therefore, numerical ocean current simulations coupled with egg and larval Lagrangian transport models remain the most common approach for the assessment of marine larval connectivity. Inferred larval connectivity may differ depending on the type of connectivity considered; consequently, the prioritisation of sites for the conservation of marine populations might also differ. Here, we introduce a framework for evaluating and designing MPA networks based on the identification of connectivity hotspots using graph theoretic analysis. As a case study, we used a network of open-access areas and MPAs off Mallorca Island (Spain), and tested its effectiveness for the protection of the painted comber Serranus scriba. Outputs from network analysis were used to (1) identify critical areas for improving overall larval connectivity, (2) assess the impact of species’ biological parameters in network connectivity and (3) explore alternative MPA configurations to improve average network connectivity. Results demonstrate the potential of graph theory to identify non-trivial egg/larval dispersal patterns and emerging collective properties of the MPA network, which are relevant for increasing protection efficiency.

Degree-day models to predict carrot weevil (Coleoptera: Curculionidae) emergence and oviposition in Nova Scotia, Canada

2020 ◽  
Vol 152 (3) ◽  
pp. 374-388
Author(s):  
Suzanne Blatt ◽  
Deney Augustine Joseph ◽  
G. Christopher Cutler ◽  
A. Randall Olson ◽  
Scott White
Keyword(s):  
Nova Scotia ◽  
Adult Emergence ◽  
Hill Equation ◽  
Base Temperature ◽  
Degree Days ◽  
Eastern Canada ◽  
Leaf Stage ◽  
True Leaf ◽  
Listronotus Oregonensis ◽  
Carrot Weevil

AbstractCarrot weevil, Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae), is a pest of carrot (Daucus carota var. sativus Hoffmann; Apiaceae) throughout eastern Canada. Carrot weevil emergence and oviposition were monitored in commercial carrot fields in Nova Scotia. Cumulative degree days were calculated using a base temperature of 7 °C (DD7), and models were developed to predict cumulative emergence and oviposition using nonlinear regression. Cumulative emergence and oviposition were adequately explained as functions of DD7 by a three-parameter sigmoidal Hill equation. Our emergence model predicted initial and peak adult emergence at 35 and 387 DD7, respectively, with oviposition on carrot baits occurring as early as 42 DD7. Models were then validated to evaluate how well they performed. Oviposition on carrot plants began at the fourth true-leaf stage (342 DD7) and continued until eleventh true-leaf stage. Growers using these models can identify their window of opportunity to manage their carrot weevil populations targeting the majority of emerged adults before oviposition begins in the field.

scholarly journals The Impact of Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) on Control of Dysmicoccus neobrevipes Beardsley (Hemiptera: Pseudococcidae)

Insects ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 131 ◽  
Author(s):  
Zhenqiang Qin ◽  
Jianhui Wu ◽  
Baoli Qiu ◽  
Shaukat Ali ◽  
Andrew G. S. Cuthbertson
Keyword(s):  
Prey Consumption ◽  
The Other ◽  
Life Stages ◽  
Functional Responses ◽  
Cryptolaemus Montrouzieri ◽  
Important Predator ◽  
Major Pest ◽  
Dysmicoccus Neobrevipes ◽  
The Impact ◽  
Agave Sisalana

Cryptolaemus montrouzieri (Coleoptera: Coccinellidae) is an important predator of the mealybug Dysmicoccus neobrevipes (Hemiptera: Pseudococcidae), a major pest of Agave sisalana in China. Limited reports on the efficacy of C. montrouzieri against D. neobrevipes are available. This study reports the predatory efficacy and functional response of C. montrouzieri against D. neobrevipes under laboratory conditions. The prey consumption rate per day of 4th instar larvae of C. montrouzieri feeding on 1st instar D. neobrevipes nymphs (241.3 mealybugs) was the highest among the different larval life stages of the beetle. For C. montrouzieri, the prey consumption per day of adult females (19.8 mealybugs) was significantly higher compared to males (15.2 mealybugs) when feeding on 3rd instar D. neobrevipes nymphs. The functional responses of C. montrouzieri on 1st and 2nd instar D. neobrevipes nymphs were determined as Holling type II. The search rates of C. montrouzieri 4th instar larvae towards the 1st and 2nd instar nymphs of D. neobrevipes were higher than those of the other beetle life stages. In addition, the handling times of 4th instar larvae were shorter than those of the other beetle life stages. The results from this study indicate that C. montrouzieri can be used as a predator of D. neobrevipes and, therefore, it should be evaluated further for use as a biocontrol agent in D. neobrevipes management programs.

scholarly journals Global warming is changing the dynamics of Arctic host–parasite systems

2005 ◽  
Vol 272 (1581) ◽  
pp. 2571-2576 ◽  
Author(s):  
S.J Kutz ◽  
E.P Hoberg ◽  
L Polley ◽  
E.J Jenkins
Keyword(s):  
Climate Change ◽  
Parasitic Nematode ◽  
Global Climate ◽  
Canadian Arctic ◽  
Domestic Animals ◽  
The Arctic ◽  
Infectious Agents ◽  
Infection Pressure ◽  
Host Parasite ◽  
The Impact

Global climate change is altering the ecology of infectious agents and driving the emergence of disease in people, domestic animals, and wildlife. We present a novel, empirically based, predictive model for the impact of climate warming on development rates and availability of an important parasitic nematode of muskoxen in the Canadian Arctic, a region that is particularly vulnerable to climate change. Using this model, we show that warming in the Arctic may have already radically altered the transmission dynamics of this parasite, escalating infection pressure for muskoxen, and that this trend is expected to continue. This work establishes a foundation for understanding responses to climate change of other host–parasite systems, in the Arctic and globally.

scholarly journals Should we redefine meiofaunal organisms? The impact of mesh size on collection of meiofauna with special regard to nematodes

2020 ◽  
Vol 54 (4) ◽  
pp. 1135-1143
Author(s):  
C. Ptatscheck ◽  
S. Gehner ◽  
W. Traunspurger
Keyword(s):  
Mesh Size ◽  
Nematode Species ◽  
Life Stages ◽  
Collection Method ◽  
Benthic Food Web ◽  
Current Definition ◽  
Standard Collection ◽  
Benthic Food ◽  
Definition Of ◽  
The Impact

Abstract Meiofaunal organisms are the predominant metazoans in benthic systems and important members of the benthic food web. They are defined by mesh size and specifically by their retention on a sieve with a 44-µm mesh size. In this study, we examined the accuracy of this standard collection method by counting the number of meiobenthic individuals, life stages and nematode species in a sample. A filter cascade consisting of five different mesh sizes (41 µm, 30 µm, 20 µm, 10 µm and 1 µm) was used to fractionate a natural freshwater meiobenthic collection, and the individuals in each fraction were then counted. In line with the current definition of meiofauna, all tardigrades, microcrustaceans, chironomids and oligochaetes were retained by the largest mesh size, whereas 9% of the rotifers were first retained on the 30-µm meshes. For nematodes, 23% were not retained on the 41-µm meshes and individuals were collected even from the 1-µm fraction. With declining mesh size, the yield of retained nematodes increased, the age structure shifted to juveniles, evenness declined, and the species composition changed. As all of these findings were significant, this study therefore shows that the current definition of meiofauna is not sufficient to encompass the entire spectrum of meiofauna present in a sample and may result in misleading assessments of the diversity and composition of these organisms. We therefore propose that, especially for nematodes, a definition based on a smaller mesh size (at least 20 µm) is more appropriate.

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