Influence of phosphorus and potassium fertilization on damage to alfalfa, Medicago sativa L., by the alfalfa weevil, Hypera postica (Gyllenhall) and potato leafhopper, Empoasca fabae (Harris)

AbstractLarval and adult populations of the Egyptian alfalfa weevil (EAW) Hypera brunneipennis (Boheman) (Coleoptera: Curculionidae) was monitored after application of the entomopathogenic fungus Beauveria bassiana in the alfalfa field (Medicago sativa L.) in two successive seasons 2014/2015 and 2015/2016. The second and last generation of the weevil on April 10, 2016, was controlled by only one application with the conidiospores of the entomopathogenic fungus B. bassiana (3 × 108 spores/ml). Accordingly, the larval population decreased from 16.07 ± 1.09 in season 2015/2016 to 7.37 ± 0.05 individuals/50 sweep net double strokes in season 2016/2017. Also, the adult weevil’s population decreased from 5.66 ± 0.8 to 2.55 ± 0.6 individuals/50 sweep net double strokes in the two seasons, respectively. 39.66% mortality rate was recorded in the Hypera brunneipennis adults aestivated under loose bark of the surrounding eucalyptus trees, which received the application of B. bassiana in the field. Another application with the fungus, targeting the second generation of the pest adults in alfalfa each season, will undoubtedly lead to a further decrease in the pest population.

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Demographic studies of Oomyzus incertus (Hymenoptera: Eulophidae), a larval parasitoid of Hypera postica (Coleoptera: Curculionidae), treated with four organophosphorous insecticides

The Canadian Entomologist ◽

10.4039/n04-067 ◽

2005 ◽

Vol 137 (4) ◽

pp. 488-491

Author(s):

Qodrat Sabahi ◽

Khalil Talebi

Keyword(s):

Life Cycle ◽

Medicago Sativa ◽

Fourth Instar ◽

Northern Iran ◽

Alfalfa Weevil ◽

Hypera Postica ◽

Larval Parasitoid ◽

Organophosphorous Insecticides

The alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae), can severely damage the first cutting of alfalfa, Medicago sativa L. (Fabaceae), in much of Iran. The pest has been parasitized by several parasitoids including Oomyzus incertus (Ratzeburg) (Hymenoptera: Eulophidae), a gregarious larval endoparasitoid. This wasp can parasitize up to 30% of weevil larvae in alfalfa fields in northern Iran. It produces three to four generations per year, and the female prefers the fourth instar of the host for oviposition. Each female lays 2 to 22 eggs per host, which hatch within 47–60 h. The life cycle is completed in about 2 weeks, upon pupation inside the host. This species is predominantly present during the summer months in alfalfa fields (Streams and Fuester 1967).

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Evaluation of Alfalfa Weevil (Coleoptera: Curculionidae) Densities and Regrowth Characteristics of Alfalfa Grazed by Sheep in Winter and Spring

Journal of Entomological Science ◽

10.18474/0749-8004-39.4.598 ◽

2004 ◽

Vol 39 (4) ◽

pp. 598-610 ◽

Cited By ~ 3

Author(s):

Hayes B. Goosey ◽

Patrick G. Hatfield ◽

Sue L. Blodgett ◽

S. Dennis Cash

Keyword(s):

Crude Protein ◽

Forage Yield ◽

Sheep Grazing ◽

Alfalfa Weevil ◽

Nutrient Quality ◽

Hypera Postica ◽

Medicago Sativa L ◽

The Impact ◽

Neutral Detergent Fibers ◽

Crop Health

Fall regrowth of alfalfa, Medicago sativa (L.), serves as a major source of winter pasture for Montana sheep producers. In years of drought, alfalfa fields are extensively winter/spring grazed; however, the impact on crop health is unknown. Alfalfa paddocks were continuously grazed for 95 d in 2002 and 98 d in 2003 during winter and spring to determine the impact on spring and summer alfalfa regrowth, nutrient quality characteristics, and alfalfa weevil, Hypera postica Gyllenhal, densities. Grazed and non-grazed forage yield, crude protein (%), and acid and neutral detergent fibers (%) did not differ at harvest (P> 0.17) during either study year. Acid and neutral detergent fibers (kg/ha) were greater (P < 0.05) in non-grazed compared to grazed plots during 2002–2003. Alfalfa weevil densities were lower in grazed than non-grazed plots (P< 0.03) over four sampling dates during both study years. Winter/spring sheep grazing appears to offer potential for alfalfa weevil management without compromising yield or nutritive factors of subsequent alfalfa production.

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Resistance to the alfalfa weevil in the Iranian collection of Medicago sativa

Tropical Grasslands - Forrajes Tropicales ◽

10.17138/tgft(8)263-279 ◽

2020 ◽

Vol 8 (3) ◽

pp. 263-279

Author(s):

Mohammad Reza Abbasi

Keyword(s):

Medicago Sativa ◽

Plant Height ◽

Morphological Traits ◽

Growth Habit ◽

Breeding Programs ◽

Alfalfa Weevil ◽

Hypera Postica ◽

Positive Linear Relationship ◽

Fall Dormancy ◽

Range Test

The Iranian collection of Medicago sativa (alfalfa, 502 accessions) was evaluated under field conditions to identify variation in resistance to the alfalfa weevil (Hypera postica Gyllenhal) between accessions over 4 years. Twenty-one accessions were identified as resistant (score 3) to semi-resistant (score 5) based on K-means cluster analysis. These materials were grouped into 10 groups by means of Duncan's Multiple Range Test. Susceptibility to alfalfa weevil was significantly correlated with some of the agro-morphological traits such as plant height (r = 0.314, P<0.01), regrowth rate (r = 0.435, P<0.01) and fall dormancy score (r = 0.284, P<0.01). In general, the resistant germplasm originated from elevated regions at high latitudes, where a co-evolution between the plant and the pest may have taken place. Multiple regression analysis showed a positive linear relationship between susceptibility to the alfalfa weevil and traits such as growth habit, plant height, length and width of the central leaflet and regrowth rate. The resulting bi-plot based on factor analysis ranked accessions for susceptibility to the pest. The identified germplasm should prove useful in alfalfa breeding programs to develop accessions resistant to the alfalfa weevil.

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Behavioral and Reproductive Response of Caged Empoasca fabae (Homoptera: Cicadellidae) to Vegetation Density of a Host Legume and a Non-Host Grass

Journal of Entomological Science ◽

10.18474/0749-8004-29.1.66 ◽

1994 ◽

Vol 29 (1) ◽

pp. 66-81 ◽

Cited By ~ 2

Author(s):

Lane M. Smith ◽

William O. Lamp ◽

Edward J. Armbrust

Keyword(s):

Relative Activity ◽

Potato Leafhopper ◽

Empoasca Fabae ◽

Plant Surface ◽

Vegetation Density ◽

Digitaria Sanguinalis ◽

Reproductive Response ◽

Choice Tests ◽

Medicago Sativa L ◽

Density Results

Behavior and reproduction of potato leafhopper, Empoasca fabae (Harris) (Homoptera: Cicadellidae), were examined in the laboratory in response to varying densities of leafhoppers, a host legume (alfalfa, Medicago sativa L.), and a non-host grass (large crabgrass, Digitaria sanguinalis L.). A series of caged treatments with increasing crabgrass density per cage resulted in a corresponding series of decreasing oviposition and decreasing number of primary oocytes per female. Oviposition and number of primary oocytes were reduced by approximately 30% at the highest grass density. However, adult activity as measured by percentage of leafhoppers observed on alfalfa, in flights per minute, and on sides of cage, remained unchanged with increasing crabgrass density. When responses given at crabgrass densities were compared with pure alfalfa of equivalent vegetation density (plant surface area), activity in the presence of crabgrass was two to four times larger than alfalfa alone of equivalent vegetation density, with the highest increases occurring after 1700 h and with greatest crabgrass density. Results suggest that greater relative activity induced by crabgrass volatiles may have been responsible for reduced oviposition and reduced tenure time on alfalfa nearest to crabgrass in two-choice tests.

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Effects of harvesting systems on yield, persistence, and nutritive value of alfalfa

Canadian Journal of Plant Science ◽

10.4141/cjps92-095 ◽

1992 ◽

Vol 72 (3) ◽

pp. 793-799 ◽

Cited By ~ 11

Author(s):

G. Bélanger ◽

J. E. Richards ◽

R. E. McQueen

Keyword(s):

Medicago Sativa ◽

Nutritive Value ◽

Rest Period ◽

Growth Period ◽

Harvest Management ◽

The Third ◽

Stage Of Development ◽

Potassium Fertilization ◽

Harvesting Systems ◽

Medicago Sativa L

The number of annual harvests and the interval between harvests affect DM yield, persistence, and nutritive value of alfalfa (Medicago sativa L.). The effects of harvesting alfalfa three times annually, with the intervals between harvests varied and with the third harvest taken prior to, during, or after the critical fall rest period, were investigated from 1985 to 1988 on a field of alfalfa established in 1984. Seven harvesting systems, comprising three harvests with varied regrowth intervals and a two-harvest system, were studied along with two rates of potassium fertilization. Harvesting alfalfa three times a year, with the third harvest taken during or after the critical fall rest period, produced the largest yields of DM, digestible DM, and crude protein. Dry matter yield was not reduced in three-harvest systems when the third harvest was taken during the critical fall rest period, provided there was an interval of approximately 500 growing degree-days between second and third harvests. Taking the first harvest at the early bud stage of development instead of the early bloom stage reduced annual DM yields. Increasing annual potassium fertilization from 200 to 400 kg K ha−1 did not affect DM yield or persistence under any harvesting system. Harvesting management of alfalfa in the fall should be based on the duration of the growth period between the second and third harvests instead of a critical fall rest period based on calendar dates.Key words: Medicago sativa L., yield, nutritive value, persistence, harvest management, K fertilization

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Phloem injury and repair following potato leafhopper feeding on alfalfa stems

Canadian Journal of Botany ◽

10.1139/b99-005 ◽

1999 ◽

Vol 77 (4) ◽

pp. 537-547 ◽

Cited By ~ 1

Author(s):

Carol L. Ecale Zhou ◽

Elaine A Backus

Keyword(s):

Medicago Sativa ◽

Side Wall ◽

Wound Response ◽

Potato Leafhopper ◽

Blue Staining ◽

Empoasca Fabae ◽

Sieve Elements ◽

Phloem Cell ◽

Sieve Tubes ◽

Injury And Repair

We examined phloem injury and repair over an 8-day period following probing (feeding with piercing-sucking mouthparts inserted in plant) by the potato leafhopper, Empoasca fabae (Harris) (Homoptera: Cicadellidae), in stems of alfalfa, Medicago sativa L. A videomicrography technique was used to apply standard-duration probing by potato leafhoppers on alfalfa stems. Leafhopper-induced plant responses, observed using transmission electron microscopy and fluorescence microscopy, included phloem cell wall loosening and collapse, increased cytoplasmic density and dissolution of necrotic phloem cells, enlargement of nuclei and nucleoli in surviving cells, increased mitotic activity, thickening of phloem cell walls, formation of short and irregularly shaped wound sieve elements (often with side-wall sieve plates), accelerated chloroplast maturation and formation of abnormally large starch grains, and generation of phloem transfer cells from companion cells. Aniline blue staining of callose in sieve elements revealed that wound sieve tubes circumvented damaged phloem by 8 days after leafhopper-induced injury. These new sieve tubes often developed in the interfascicular area adjacent to the wounded bundles.Key words: plant wound response, wound phloem, sieve element, transfer cell, leafhopper feeding, Empoasca fabae, Medicago sativa.

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