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CC BY-NC-ND V4.0, Open Access
Thesis
Economic injury level, action threshold and population development of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera:Aphididae), on green peas, Pisum sativum L.
Washington State University
Master of Science (MS), Washington State University
08/1985
DOI:
https://doi.org/10.7273/000007349
Abstract
Economic injury level, action threshold, and population development of the pea aphid (PA}, Acyrthosiphon pisum (Harris}, were investigated during 1983-1984. Four experiments, incorporating 12 treatments and 6 replications, were conducted. PA densities, simulating those in commercial pea fields, were established using a short residual insecticide to manipulate early season infestation levels.
PA population growth approximated a geometric series. Maximum densities of 268.8 and 99.4 aphids per plant (A/P} at full-bloom were recorded for 2 experiments in 1983. Populations declined to 53.9 and 2.3 A/Pat harvest due to a fungal epizootic. PA population development was delayed 3 weeks in 1984. At full-bloom, populations averaged less than 1 A/Pin each of 2 experiments. Maximum PA densities of 97.0 and 128.3 A/P were recorded at harvest.
A non-linear function relating pea yield to accumulated aphid feeding days (AFD} is described. The model approximates 2 phases of the generalized sigmoid infestation-yield curve. An upper maximum yield plateau, and a linear region of rapidly decreasing yield are approximated. Beyond 1800 AFD, a lower minimum yield plateau is hypothesized. Best fit equations for 1983 and 1984 were
Y= 3.555 - 0.662 e0.708(1n(AFD) - 5.5) r2=0.87
and
Y= 5.463 - 0.554 e0.570(1n(AFD) - 5.4) r2=0.61
Economic injury levels (EIL) calculated from these models were 22.2 and 18.2 AFD, respectively.
Action threshold (ACT) estimates were determined from linear regression estimates of yield vs. A/P at full-bloom. Action thresholds were an average of 3.6 and 0.3 A/P for the years 1983 and 1984, respectively. Differences in the EIL and ACT estimates for the years 1983 and 1984 probably reflect seasonal variations in maximum yield potential and temporal changes in PA stress.
The pea quality components, tenderometer (TD) and sieve size, were altered by PA densities exceeding the EIL. High AFD levels increased TD and decreased sieve size significantly when compared to aphid free controls. Protein content of green peas was not significantly altered by PA feeding.
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Details
- Title
- Economic injury level, action threshold and population development of the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera:Aphididae), on green peas, Pisum sativum L.
- Creators
- George Craig Yencho
- Contributors
- Louis W. Getzin (Chair)Wilbur C. Anderson (Committee Member)Garrell E. Long (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Entomology
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 54
- Identifiers
- 99901225854401842
- Language
- English
- Resource Type
- Thesis