Leaf nutrient levels and the spatio-temporal distributions of Plutella xylostella and its larval parasitoids Diadegma insulare and Microplitis plutellae in canola

AbstractA detailed knowledge on the spatial distribution of pests is crucial for predicting population outbreaks or developing control strategies and sustainable management plans. The diamondback moth, Plutella xylostella, is one of the most destructive pests of cruciferous crops worldwide. Despite the abundant research on the species’s ecology, little is known about the spatio-temporal pattern of P. xylostella in an agricultural landscape. Therefore, in this study, the spatial distribution of P. xylostella was characterized to assess the effect of landscape elements in a fine-scale agricultural landscape by geostatistical analysis. The P. xylostella adults captured by pheromone-baited traps showed a seasonal pattern of population fluctuation from October 2015 to September 2017, with a marked peak in spring, suggesting that mild temperatures, 15–25 °C, are favorable for P. xylostella. Geostatistics (GS) correlograms fitted with spherical and Gaussian models showed an aggregated distribution in 21 of the 47 cases interpolation contour maps. This result highlighted that spatial distribution of P. xylostella was not limited to the Brassica vegetable field, but presence was the highest there. Nevertheless, population aggregations also showed a seasonal variation associated with the growing stage of host plants. GS model analysis showed higher abundances in cruciferous fields than in any other patches of the landscape, indicating a strong host plant dependency. We demonstrate that Brassica vegetables distribution and growth stage, have dominant impacts on the spatial distribution of P. xylostella in a fine-scale landscape. This work clarified the spatio-temporal dynamic and distribution patterns of P. xylostella in an agricultural landscape, and the distribution model developed by geostatistical analysis can provide a scientific basis for precise targeting and localized control of P. xylostella.

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TRENDS IN LEAF NUTRIENT LEVELS IN COMMERCIAL HIGHBUSH BLUEBERRY PLANTINGS IN MICHIGAN

Acta Horticulturae ◽

10.17660/actahortic.1989.241.24 ◽

1989 ◽

pp. 157-161

Author(s):

E.J. Hanson

Keyword(s):

Highbush Blueberry ◽

Nutrient Levels ◽

Leaf Nutrient Levels

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Changes in Numbers in the Parasitoid Complex Associated With the Diamond-Back Moth, Plutella Xylostella (L.) (Lepidoptera), in Victoria.

Australian Journal of Zoology ◽

10.1071/zo9790981 ◽

1979 ◽

Vol 27 (6) ◽

pp. 981 ◽

Cited By ~ 27

Author(s):

S Goodwin

Keyword(s):

High Temperatures ◽

Plutella Xylostella ◽

Winter Period ◽

Parasitoid Species ◽

Primary Parasitoid ◽

Parasitoid Complex ◽

Larval Parasitoids ◽

Pesticide Treatment ◽

Drought Conditions ◽

Rate Of Recovery

Between 1972 and 1974, a study was made of parasitoids of P. xylostella naturally infesting four successive crops of cabbages which had not received any pesticide treatment. Parasitism fluctuated in each crop, averaging 49% during the study. The major parasitoid species were Diadegma cerophaga, Thyraeella collaris and Diadegma rapi, which averaged 93% of parasitism over the study period. Six minor primary parasitoid and one hyperparasite species were also recorded. Parasitoid activity was high during spring and summer, although extremely high temperatures during summer reduced numbers of both the host and its parasitoids. Drought conditions accentuated this. Parasitism in autumn depended upon the severity of this depletion and on the ensuing rate of recovery. The more important larval parasitoids were closely synchronized with host numbers, with a distinct lag during the winter period.

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Evidence of Diadegma insulare (Cresson), a Parasitoid of Diamondback Moth, Plutella xylostella L., Present in Various Habitats

Journal of Biological Sciences ◽

10.3923/jbs.2001.742.743 ◽

2001 ◽

Vol 1 (8) ◽

pp. 742-743 ◽

Cited By ~ 3

Author(s):

Idris, A. B. ◽

E. Grafius .

Keyword(s):

Plutella Xylostella ◽

Diamondback Moth ◽

Diadegma Insulare

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Spatially mismatched trophic dynamics: cyclically outbreaking geometrids and their larval parasitoids

Biology Letters ◽

10.1098/rsbl.2009.1002 ◽

2010 ◽

Vol 6 (4) ◽

pp. 566-569 ◽

Cited By ~ 24

Author(s):

Snorre B. Hagen ◽

Jane U. Jepsen ◽

Tino Schott ◽

Rolf A. Ims

Keyword(s):

Trophic Interactions ◽

Travelling Waves ◽

Methodological Approach ◽

Spatial Dynamics ◽

Population Cycles ◽

Trophic Levels ◽

Trophic Dynamics ◽

Spatial Mismatch ◽

Larval Parasitoids ◽

Spatio Temporal

For trophic interactions to generate population cycles and complex spatio-temporal patterns, like travelling waves, the spatial dynamics must be matched across trophic levels. Here, we propose a spatial methodological approach for detecting such spatial match–mismatch and apply it to geometrid moths and their larval parasitoids in northern Norway, where outbreak cycles and travelling waves occur. We found clear evidence of spatial mismatch, suggesting that the spatially patterned moth cycles in this system are probably ruled by trophic interactions involving other agents than larval parasitoids.

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Influence of Selected Insecticides on the Population Dynamics of Diamondback Moth (Lepidoptera: Plutellidae) and Its Parasitoid, Diadegma insulare (Hymenoptera: Ichneumonidae), in Cabbage

Journal of Entomological Science ◽

10.18474/0749-8004-38.1.59 ◽

2003 ◽

Vol 38 (1) ◽

pp. 59-71 ◽

Cited By ~ 10

Author(s):

Travis A. Hill ◽

Rick E. Foster

Keyword(s):

Population Dynamics ◽

Plutella Xylostella ◽

Diamondback Moth ◽

Diadegma Insulare ◽

Economic Thresholds ◽

Percent Parasitism

The effects of insecticides on the diamondback moth, Plutella xylostella (L)., and its parasitoid, Diadegma insulare (Cresson), were evaluated in the field. Insecticides applied for control of the diamondback moth caused variations in parasitism by D. insulare ranging from 20 to 84%. Permethrin applications were effective at controlling diamondback moth. Applications of spinosad also resulted in low diamondback moth populations; however, percent parasitism was higher than in untreated plots and over 4× higher than in plots treated with permethrin. Selective materials that conserve D. insulare populations and maintain diamondback moth populations below economic thresholds may reduce the frequency of application, thus prolonging the efficacy of these materials.

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Nutrient status of sugar cane in relation to leaf nutrient concentration

Australian Journal of Experimental Agriculture ◽

10.1071/ea9680606 ◽

1968 ◽

Vol 8 (34) ◽

pp. 606 ◽

Cited By ~ 2

Author(s):

ICR Holford

Keyword(s):

Sugar Cane ◽

Field Experiments ◽

Leaf Tissue ◽

Growth Period ◽

Nutrient Status ◽

Maximum Growth ◽

Nutrient Concentrations ◽

Ratoon Crop ◽

Nutrient Levels ◽

Leaf Nutrient Levels

The nitrogen, phosphorus, and potassium requirements of sugar cane were studied in relation to the concentration of these elements in the leaf tissue of three varieties of sugar cane grown commercially in Fiji. Percentage yields of sugar cane in fertilizer field experiments were highly correlated with leaf nutrient levels in the control plots, provided leaf sampling was carried out during the maximum growth period of mid- January to mid-May. For each nutrient there was a marginal zone of leaf concentration below which crops always gave significant yield responses to applied nutrients and above which crops failed to respond. Marginal zones for crops sampled during mid-March to mid-May were 1.4-2.0 per cent for nitrogen, 0.13-0.21 per cent for phosphorus, and 0.9-1.5 per cent oven dry leaf for potassium. Within the deficient range of leaf nutrient concentrations there was little relationship between optimum rates of fertilizer required to correct the deficiency and leaf nutrient levels of unfertilized cane. Because of the lateness of sampling, any indication of fertilizer requirement would only be applicable to a subsequent ratoon crop.

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