Abstract
Adults of the alfalfa seed chalcid (ASC), Bruchophagus roddi Gussakovskii, were monitored in four counties in Oklahoma from mid-May until the end of September, with maximal population densities generally occurring in August. Female ASC in the alfalfa fields outnumbered males by ratios of 1.5:1 to 2:1. Peaks of adult ASC emergence in different fields ranged from three to six per year. Four genera of ASC parasites were collected: Liodontomerus perplexus Gahan, Tetrastichus bruchophagus Gahan, Trimeromicrus macu latus Gahan, and Eupelmus allynii (French). Percentage of adult parasites in the host/ parasite complex was 41.5% in 1983 and 55.7% in 1984. Adult parasites were more numerous than adult ASC during the later part of the season, and peak densities of parasites occurred one week later than peak densities of ASC. Female parasites outnumbered males by ratios of 3:1 to 7:1. This study shows that during the alfalfa seed production season in Oklahoma there is no safe date or time period where adult ASC are not present in the fields. Degree day accumulations were calculated for each field and compared to peaks in the field data to determine if peak ASC populations could be predicted. Although the majority of the ASC peaks did occur near a predicted date, the degree day calculations did not account for all of the variation in ASC generation time. Each spring, adult alfalfa seed chalcids (ASC), Bruchophagus roddi Gussakov skii, and ASC parasites emerge from alfalfa (Medicago sativa L.) seeds where they overwintered as diapausing prepupae (Urbahns, 1920). Emergence of ASC and their parasites begins in Oklahoma in late April to early May (Thoenes and Moffett, 1987a, b). Soon thereafter, adult ASC can be found wherever alfalfa plants are setting seed (Sorenson, 1930). ASC and their parasites vary in population density, species composition, and time of activity in different areas across the United States (Bacon et al., 1964). The seasonal occurrence of adult ASC and ASC parasite populations in Oklahoma alfalfa fields has never been adequately investigated. This paper addresses the fundamental lack of phenological data on ASC in Oklahoma, which can be applied to many other areas within the United States. Methods and Materials Field populations of ASC adults can be sampled by several methods, but col lecting ASC with a sweep net is the fastest, easiest, and least costly method (Johansen, 1979). Sweep samples were taken twice a week during the 1983 season at fields 1 and 2 (near Stillwater in Payne County, and near Perry in Noble County, respectively) and during the 1984 season at fields 3 and 4 (near Woodward in 1 Current address: USDA-ARS Carl Hayden Bee Research Center, 2000 E. Allen Rd., Tucson, Arizona 85719. Accepted for publication 21 September 1989. This content downloaded from 207.46.13.53 on Thu, 01 Sep 2016 04:23:24 UTC All use subject to http://about.jstor.org/terms 362 JOURNAL OF THE KANSAS ENTOMOLOGICAL SOCIETY Woodward County and on the South Central Research Station in Chickasha County). Management of both fields in 1983 consisted of fencing off 0.5 hectares in spring and allowing alfalfa to bloom and produce flowers and fruits throughout the season. Neither field was cut during the study, and no insecticide was applied. The alfalfa morphology changed during the season depending on plant maturity: from leaves and flowers on early season upright plants, to mainly long stems on mid-season lodged plants, and finally late season regrowth from the crown of newly blooming plants. This type of field management is not ideal for sampling due to the lack of a constant source of seeds throughout the season. Also, lodged plants with thick stems are harder to sweep the net through to obtain the sample. In field 2 the first growth of the season was infested with blue alfalfa aphids, Acyrthosiphon kondoi Shinji, to the extent that initial growth was stunted, with very few flowers and virtually no seeds produced until mid-July. Management at both fields in 1984 consisted of staggered cutting dates for different sections of the field to provide new growth and blooms throughout the season. Samples were taken from the area where new seeds were being set. Field 3 was 6 hectares (divided into 24 equal subplots) and field 4 was 0.5 hectares (divided into 9 equal plots) in size. In field 3, toxaphene was applied at a rate of 1 kg per hectare on 23 July to control grasshoppers (Melanoplus spp.). No insec ticides were applied in field 4. Each sample consisted of 100 pendulum sweeps. Length of each sweep through vegetation was 1 m. Sweeps were kept at a level so that half of the 38 cm diameter net was in contact with vegetation during the motion. Total vegetation covered in 100 sweeps was estimated to be 30 m2.
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Claims 11
Claim · model-written summary
Alfalfa seed chalcid adults peaked generally in August.
- Taxon
- alfalfa
Medicago sativat0 - Interactor
- Bruchophagus roddi GussakovskiiBruchophagus roddie0pest
- Outcome
- maximal population densitiese0
- Direction
- maximale0
- Setting
- Oklahomae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Adults of the alfalfa seed chalcid (ASC), Bruchophagus roddi Gussakovskii, were monitored in four counties in Oklahoma from mid-May until the end of September, with maximal population densities generally occurring in August.”
Claim · model-written summary
Female chalcids outnumbered males by 1.5:1 to 2:1.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- Female ASCe0
- Direction
- outnumberede0
- Value
- 1.5:1 to 2:1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Female ASC in the alfalfa fields outnumbered males by ratios of 1.5:1 to 2:1.”
Claim · model-written summary
Adult chalcid emergence had three to six peaks annually.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- Peaks of adult ASC emergencee0
- Value
- three to six per yeare0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Peaks of adult ASC emergence in different fields ranged from three to six per year.”
Claim · model-written summary
Four genera of chalcid parasites were collected.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- ASC parasites were collectede0
- Value
- Four generae0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Four genera of ASC parasites were collected: Liodontomerus perplexus Gahan, Tetrastichus bruchophagus Gahan, Trimeromicrus macu latus Gahan, and Eupelmus allynii (French).”
Claim · model-written summary
Adult parasites were 41.5% of the complex in 1983.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- Percentage of adult parasites in the host/ parasite complexe0
- Value
- 41.5%e0
- Qualifier
- 1983e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Percentage of adult parasites in the host/ parasite complex was 41.5% in 1983 and 55.7% in 1984.”
Claim · model-written summary
Adult parasites were 55.7% of the complex in 1984.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- Percentage of adult parasites in the host/ parasite complexe0
- Value
- 55.7%e0
- Qualifier
- 1984e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Percentage of adult parasites in the host/ parasite complex was 41.5% in 1983 and 55.7% in 1984.”
Claim · model-written summary
Adult parasites exceeded adult chalcids late in the season and peaked one week later.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- Adult parasitese0
- Direction
- more numerouse0
- Value
- one weeke0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Adult parasites were more numerous than adult ASC during the later part of the season, and peak densities of parasites occurred one week later than peak densities of ASC.”
Claim · model-written summary
Female parasites outnumbered males by 3:1 to 7:1.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- Female parasitese0
- Direction
- outnumberede0
- Value
- 3:1 to 7:1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Female parasites outnumbered males by ratios of 3:1 to 7:1.”
Claim · model-written summary
No period during alfalfa seed production was free of adult chalcids in Oklahoma fields.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- adult ASC are not present in the fieldse0
- Setting
- Oklahomae0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“during the alfalfa seed production season in Oklahoma there is no safe date or time period where adult ASC are not present in the fields”
Claim · model-written summary
Most chalcid peaks occurred near predicted degree day dates, but calculations missed some generation time variation.
- Taxon
- alfalfaMedicago sativat0
- Outcome
- ASC peaks did occur near a predicted datee0
- Comparator
- predicted datee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“alfalfa seed chalcids”
e0“Although the majority of the ASC peaks did occur near a predicted date, the degree day calculations did not account for all of the variation in ASC generation time.”
Claim · model-written summary
Blue alfalfa aphid infestation stunted initial alfalfa growth with few flowers and virtually no seeds until mid July.
- Taxon
- alfalfaMedicago sativae0
- Interactor
- Acyrthosiphon kondoi Shinji
Acyrthosiphon kondoie0pest - Outcome
- initial growth was stunted, with very few flowers and virtually no seeds producede0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In field 2 the first growth of the season was infested with blue alfalfa aphids, Acyrthosiphon kondoi Shinji, to the extent that initial growth was stunted, with very few flowers and virtually no seeds produced until mid-July.”