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

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).

Evaluation and Calibration of Sampling Methods Used to Estimate Abundance of Alfalfa Weevil Larvae (Coleoptera: Curculionidae)

1992 ◽  
Vol 27 (3) ◽  
pp. 202-208 ◽  
Author(s):  
John M. Luna ◽  
F. William Ravlin
Keyword(s):  
Sampling Methods ◽  
Fourth Instar ◽  
Larval Abundance ◽  
Alfalfa Weevil ◽  
Hypera Postica ◽  
Accuracy And Precision ◽  
Coefficients Of Variation ◽  
Plastic Bag ◽  
Calibration Equations ◽  
Sweep Net

Three sampling methods for estimating abundance of alfalfa weevil larvae (Hypera postica Gyllenhal) were evaluated for both accuracy and precision. A plastic bag/Tullgren funnel method collected significantly fewer second, third, fourth instar and total larvae than did the bucket-shake method. Calibration equations were developed to convert intensity estimates (alfalfa weevil larvae per alfalfa stem) obtained from the plastic bag/Tullgren funnel method to bucket-shake estimates. Sweep-net sampling produced significantly lower coefficients of variation than both bucket-shake and plastic bag/Tullgren funnel sampling methods, however mean estimates of larval abundance obtained from sweep-net sampling could be reliably converted to bucket-shake estimates for only fourth instar larvae.

BIOLOGICAL CONTROL OF THE ALFALFA WEEVIL HYPERA POSTICA (COLEOPTERA: CURCULIONIDAE) IN NEW YORK

1971 ◽  
Vol 103 (12) ◽  
pp. 1653-1658 ◽  
Author(s):  
R. Larry Richardson ◽  
Dean E. Nelson ◽  
Alan C. York ◽  
George G. Gyrisco
Keyword(s):  
New York ◽  
Biological Control ◽  
Life Cycle ◽  
Control Agent ◽  
Effective Control ◽  
Critical Levels ◽  
Alfalfa Weevil ◽  
Hypera Postica ◽  
Late Fall ◽  
Natural Dispersal

AbstractTwo hymenopterous parasites Bathyplectes curculionis (Thomson) and Tetrastichus incertus (Ratzeburg) parasitized 16.5% of their principal host the alfalfa weevil Hypera postica (Gyllenhal) in 1970. A total of 2703 parasites was reared and released in localities where their activity was reported low or non-existent prior to this study. Maximum parasitism by T. incertus and B. curculionis occurred later than periods of peak weevil larvae activity; however, T. incertus emerged earlier in several areas possibly as a natural adjustment of its life cycle, and B. curculionis persisted in multiple non-diapausing generations until late fall. The braconid parasite Microtonus aethiops (Nees) shows promise in becoming a very effective control agent through its ability to prevent weevil oviposition now that it is rapidly dispersing throughout New York. Having parasites established statewide through both releases and natural dispersal has lowered weevil populations below critical levels, and will increase parasite effectiveness in dealing with future alfalfa weevil generations.

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

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.

Establishment of Bathyplectes anurus (Hymenoptera: Ichneumonidae), a larval parasitoid of the alfalfa weevil, Hypera postica (Coleoptera: Curculionidae) in Japan

2005 ◽  
Vol 34 (2) ◽  
pp. 144-151 ◽  
Author(s):  
Megumi Shoubu ◽  
Masami Okumura ◽  
Akinori Shiraishi ◽  
Hidenori Kimura ◽  
Masami Takagi ◽  
...  
Keyword(s):  
Alfalfa Weevil ◽  
Hypera Postica ◽  
Larval Parasitoid

DISPLACEMENT OF BATHYPLECTES CURCULIONIS (THOMS.) (HYMENOPTERA: ICHNEUMONIDAE) BY B. ANURUS (THOMS.) IN EASTERN ONTARIO POPULATIONS OF THE ALFALFA WEEVIL, HYPERA POSTICA (GYLL.) (COLEOPTERA: CURCULIONIDAE)

1990 ◽  
Vol 122 (4) ◽  
pp. 641-645 ◽  
Author(s):  
D.G. Harcourt
Keyword(s):  
Aggressive Behaviour ◽  
Reproductive Capacity ◽  
Alfalfa Weevil ◽  
Hypera Postica ◽  
Parasitoid Community ◽  
Larval Parasitoid ◽  
Direct Competition ◽  
Eastern Ontario ◽  
Better Than

AbstractBathyplectes anurus (Thoms.) has displaced B. curculionis (Thorns.) as the main larval parasitoid in populations of the alfalfa weevil, Hypera postica (Gyll.), in eastern Ontario. Following its belated spread to the Bay of Quinte dairy belt, it used a combination of r and K strategies to assert its superiority: a greater reproductive capacity, more rapid search and handling, and more aggressive behaviour. Also, it is not subject to encapsulation by the host and reduces direct competition with the entomopafhogenic fungus Zoophthora phytonomi (Arthur) by laying its eggs in older hosts that have a greater probability of escaping death from disease. Taken together, these factors have enabled it to perform better than B. curculionis and to displace it in the host–parasitoid community. Moreover, it may have the potential to stabilize weevil populations during years when the fungus is enzootic.

scholarly journals Management of the Egyptian alfalfa weevil, Hypera brunneipennis (Boheman) (Coleoptera: Curculionidae), in the alfalfa, Medicago sativa L., using the entomopathogenic fungus, Beauveria bassiana (Balsamo) Vuillemin

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Monir M. M. El Husseini
Keyword(s):  
Medicago Sativa ◽  
Beauveria Bassiana ◽  
Entomopathogenic Fungus ◽  
Larval Population ◽  
Alfalfa Weevil ◽  
Alfalfa Field ◽  
Medicago Sativa L ◽  
Hypera Brunneipennis ◽  
Fungus Beauveria Bassiana ◽  
Sweep Net

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.

EFFECTS OF CARBOFURAN ON ARTHROPOD POPULATIONS AND CROP YIELD IN HAYFIELDS

1972 ◽  
Vol 104 (9) ◽  
pp. 1433-1437 ◽  
Author(s):  
C. D. Dondale
Keyword(s):  
Crop Yield ◽  
Crude Protein ◽  
Alfalfa Weevil ◽  
Hypera Postica

AbstractCarbofuran was applied to three hayfields at a rate of 0.56 kg/ha in early June. This caused significant reductions of Thysanoptera, phytophagous Coleoptera larvae (including the alfalfa weevil, Hypera postica (Gyl.)), and Cicadellidae. It caused similar reductions in Araneida and parasitoids. The differences between treated and untreated plots were no longer significant by September. Carbofuran did not significantly affect the yield of air-dried hay or of crude protein.

DIFFERENTIAL ENCAPSULATION OF TWO BATHYPLECTES PARASITOIDS AMONG ALFALFA WEEVIL STRAINS, HYPERA POSTICA (GYLLENHAL)

1991 ◽  
Vol 123 (1) ◽  
pp. 197-203 ◽  
Author(s):  
Christopher M. Maund ◽  
T.H. Hsiao
Keyword(s):  
Biological Control ◽  
Control Strategy ◽  
Laboratory Studies ◽  
Alfalfa Weevil ◽  
Hypera Postica ◽  
Biological Differences

AbstractEncapsulation of Bathyplectes curculionis (Thomson) and B. anurus (Thomson) (Hymenoptera: Ichneumonidae) was investigated by dissecting parasitized larvae of three strains of the alfalfa weevil, Hypera postica (Gyllenhal) (Coleoptera: Curculionidae). In laboratory studies, there was no encapsulation of B. curculionis in the western strain of the weevil, a significant level of encapsulation in the eastern strain of the weevil, and nearly complete encapsulation in the Egyptian strain of the weevil. The rickettsia, Wolbachia postica Hsiao and Hsiao, found only in the western strain, was not involved in encapsulation. Variation in encapsulation was due to biological differences between weevil strains. Encapsulation rates among field populations of the western and Egyptian weevils were lower than in the laboratory. Encapsulation rates of weevil populations from zones in which western and Egyptian strains overlap in southern Utah, and between eastern and western strains in Colorado, were intermediate to rates of parental strains. These results imply that B. curculionis effectiveness against the western alfalfa weevil will decline with mixing of weevil strains. Bathyplectes anurus did not evoke encapsulation and was able to develop equally well in all three weevil strains. Our findings illustrate the importance of investigating the compatibility between alfalfa weevil strains and their parasitoids in devising a sound biological control strategy.

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