SPECIES COMPOSITION OF PEA APHID (HOMOPTERA: APHIDIDAE) PRIMARY AND SECONDARY PARASITOIDS IN WISCONSIN

1987 ◽  
Vol 119 (11) ◽  
pp. 1055-1057 ◽  
Author(s):  
R.L. Thiboldeaux ◽  
W.D. Hutchison ◽  
D.B. Hogg

The pea aphid, Acyrthosiphon pisum (Harris), is an important pest of alfalfa, Medicago sativa L., in Wisconsin because of its characteristic potential for exponential population growth (Hutchison and Hogg 1984, 1985) and the subsequent damage in both hay quality and quantity inflicted by high populations (Cuperus et al. 1982). In Wisconsin, as in most alfalfa-producing states, there is a vast complex of natural enemies (Hutchison and Hogg 1985) that influence pea aphid population dynamics, including the hymenopteran primary parasitoids from the Aphidiidae. These primary species, however, are also attacked by several secondary parasitoids from the families Megaspilidae, Pteromalidae, and Alloxystidae.

1984 ◽  
Vol 116 (7) ◽  
pp. 950-963 ◽  
Author(s):  
A. P. Gutierrez ◽  
J. U. Baumgaertner ◽  
C. G. Summers

AbstractThe field population dynamics of pea aphid (Acyrthosiphon pisum) and blue alfalfa aphid (A. kondoi) in alfalfa (Medicago sativa), as influenced by weather, competitors (Egyptian alfalfa weevil = EAW, Hypera brunneipennis), predation from coccinellids (Hippodamia convergens) and harvesting practices, are examined with a stochastic multitrophic level simulation model. The model incorporates a demand-driven functional-response model to estimate prey consumption, and a metabolic pool model to determine the rates and priorities of food allocation to respiration, growth, reproduction, and egestion.The model results compare favorably with field data, and are used to examine the effects of removal of each of the above factors on the dynamics of the aphids. The model shows that the observed density of EAW did not affect the aphid dynamics, but did reduce the standing crop of alfalfa. The predator H. convergens had a significant effect on the population dynamics of the aphids and the plant. Harvesting greatly affected the aphid population dynamics, as well as the dynamics of plant growth and reserve accumulation. However, high temperatures mediated through species-specific respiration costs and possibly a fungal pathogen were responsible for the observed dominance of blue aphid populations in the cool parts of the year and pea aphid populations during warmer parts of the year.


2005 ◽  
Vol 95 (2) ◽  
pp. 125-131 ◽  
Author(s):  
G. Kunert ◽  
W.W. Weisser

AbstractThe pea aphidAcyrthosiphon pisumHarris has been shown to produce an increasing proportion of winged morphs among its offspring when exposed to natural enemies, in particular hoverfly larvae, lacewing larvae, adult and larval ladybirds and aphidiid parasitoids. While these results suggest that wing induction in the presence of predators and parasitoids is a general response of the pea aphid, the cues and mechanisms underlying this response are still unclear. Tactile stimuli and the perception of chemical signals as well as visual signals are candidates for suitable cues in the presence of natural enemies. In this paper the hypothesis that the aphids' antennae are crucial for the wing induction in the presence of natural enemies is tested. Antennae of pea aphids were ablated and morph production was scored when aphids were reared either in the presence or the absence of predatory lacewing larvae over a six-day period. Ablation of antennae resulted in a drastic drop in the proportion of winged morphs among the offspring, both in the presence and the absence of a predator whereas predator presence increased wing induction in aphids with intact antennae, as reported in previous experiments. The results show that antennae are necessary for wing induction in the presence of natural enemies. Critical re-examination of early work on the importance of aphid antennae and tactile stimuli for wing induction suggests that a combination of tactile and chemical cues is likely to be involved not only in predator-induced wing formation but also for wing induction in response to factors such as crowding in the aphid colony.


1977 ◽  
Vol 109 (2) ◽  
pp. 277-284 ◽  
Author(s):  
A. Campbell ◽  
M. Mackauer

AbstractThe effect of temperature on the age-specific fecundity and the survival of apterous and alate virginoparous pea aphid, Acyrthosiphon pisum (Harris), from Kamloops, B.C., was measured. Demographic statistics were estimated for 10.3°, 14.8°, 19.7°, 26.1°, and 27.8°C constant and for fluctuating field temperatures. On a 24-h-day time-scale, temperature and longevity were inversely related in both morphs; total fecundity was highest at average and low constant temperatures. On a physiological time-scale, the intrinsic rate of increase (rm) was insensitive to changes in constant temperature in the range between 10° and 20°C; temperatures above 25°C were detrimental to aphid population growth and survival. Alate virginoparae generally had a longer pre-reproductive period and achieved a lower mean total fecundity than apterae maintained under identical conditions. The usefulness of laboratory measurements for the prediction of population growth under variable field temperatures is discussed. Differences in the reproductive patterns of alate and apterous pea aphids are considered in the context of the r- and K-hypothesis of selection.


Euphytica ◽  
2004 ◽  
Vol 138 (2) ◽  
pp. 133-139 ◽  
Author(s):  
B. Julier ◽  
R. Bournoville ◽  
B. Landré ◽  
C. Ecalle ◽  
S. Carré

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