BEHAVIOR OF THE PARASITOID PLEOLOPHUS BASIZONUS (HYMENOPTERA: ICHNEUMONIDAE) IN RESPONSE TO CHANGES IN HOST AND PARASITOID DENSITY

1972 ◽  
Vol 104 (1) ◽  
pp. 129-140 ◽  
Author(s):  
Peter W. Price
Keyword(s):  
Apparent Density ◽  
Mutual Interference ◽  
Egg Laying ◽  
Parasitoid Behavior ◽  
Density Dependent ◽  
Unparasitized Host ◽  
Adult Parasitoid ◽  
Escape Reaction ◽  
General Aspects

AbstractA synthesis of observations on density-dependent interactions in parasitoid populations is attempted, working from the particular aspects of discrimination against parasitized hosts and detailed observations on parasitoid behavior, to more general aspects of parasitoid ecology, dispersal, distribution, and response to host populations. Females of Pleolophus basizonus (Gravenhorst) are able to discriminate against parasitized hosts of Neodiprion swainei Middleton between narrow limits (mean densities of 0.4 to 1.4 eggs per cocoon) set by the probability of a female finding an unparasitized host. They show mutual interference in egg laying at high parasitoid:host ratios, and a density-dependent escape reaction to adult parasitoid density. These behaviors all result from the recognition of repellent trail odors left by searching females. Response of individual females to high parasitoid densities may therefore lead to dispersal, the occupation by the population of more, but not so favorable habitats, and an apparent density-independent response to host populations.

SYNCHRONY BETWEEN POPULATIONS OF THE TARNISHED PLANT BUG, LYGUS LINEOLARIS (PALISOT DE BEAUVOIS) (HEMIPTERA: MIRIDAE), AND ITS EGG PARASITOIDS IN SOUTHWESTERN QUEBEC

1995 ◽  
Vol 127 (4) ◽  
pp. 457-472 ◽  
Author(s):  
Khalid M. Al-Ghamdi ◽  
Robin K. Stewart ◽  
Guy Boivin
Keyword(s):  
Medicago Sativa ◽  
Adult Population ◽  
Egg Parasitoids ◽  
Egg Laying ◽  
Lygus Lineolaris ◽  
Degree Days ◽  
Tarnished Plant Bug ◽  
Coronilla Varia ◽  
Adult Parasitoid ◽  
Anaphes Iole

AbstractThe seasonal occurrence of four species of egg parasitoids of the tarnished plant bug (Lygus lineolaris) was determined in three different habitais: fields of mixed weeds. alfalfa (Medicago sativa L.). and crown vetch (Coronilla varia L.) in southwestern Quebec in 1991 and 1992. Parasitoids studied were the mymarids Anaphes iole Girault, Polynema pratensiphagum (Walley), and Erythmelus miridiphagus Dozier and a scelionid, Telenomus sp. Adult populations of these parasitoids showed three or four population peaks in all habitats throughout the season. Adult parasitoid activity started during the first egg-laying period of L. lineolaris at a temperature accumulation of 73 degree-days (DD). The overwintering period began in mid-October at 1277 and 1058 DD for 1991 and 1992, respectively. All the parasitoids had a strong synchrony with L. lineolaris populations; specifically, marked peaks in the adult population of all species were in synchrony with the egg-laying periods of L. lineolaris.

Evidence of density-dependent oviposition behaviour byListronotus bonariensis(Coleoptera: Curculionidae) in Canterbury pasture

1998 ◽  
Vol 88 (5) ◽  
pp. 527-536 ◽  
Author(s):  
M.R. McNeill ◽  
D.B. Baird ◽  
S.L. Goldson
Keyword(s):  
Biological Control ◽  
Field Experiments ◽  
Adult Population ◽  
Egg Laying ◽  
Oviposition Behaviour ◽  
Initial Population ◽  
Adult Density ◽  
Control Effort ◽  
Density Dependent ◽  
Age Related

AbstractArgentine stem weevil (Listronotus bonariensis) (Kuschel) is a pasture pest ofLoliumspp. in New Zealand and is the target of a classical biological control programme using the parasitoidMicroctonus hyperodaeLoan. However, laboratory experiments have indicated a strong density-dependent egg laying response which may have important implications for the biological control effort. Two field experiments were conducted using a manipulated range of weevil densities within 2.0–2.4 m–2field enclosures and oviposition activity measured by weekly sampling of grass tillers within the enclosures. In both experiments, density had no effect on general oviposition behaviour although the percentage of tillers found to be infested with eggs increased significantly at higher densities. In experiment 1,L. bonariensisexhibited strong density-dependent oviposition with a significant decline in eggs/tiller/female with increasing adult density. An initial population of fiveL. bonariensism−2oviposited 32 times more eggs/tiller/female than 200L. bonariensism−2. By comparison, density-dependent oviposition was absent in experiment 2 with eggs/tiller/female comparable for all densities. The dramatic difference between the two experiments in the expression of density-dependent oviposition was attributed to prevailing spring temperatures during the sampling interval, which in the second experiment were much cooler and delayed the onset of egg laying. It is probable that in experiment 2, oviposition was not regulated by density-dependent cues but limited by temperature and age related mortality in the adult population. The mechanism for density-dependent oviposition, its occurrence in the field and impact on the effectiveness of the parasitoidM. hyperodaeare discussed.

scholarly journals Effects of Snail Density on Growth, Reproduction and Survival ofBiomphalaria alexandrinaExposed toSchistosoma mansoni

2010 ◽  
Vol 2010 ◽  
pp. 1-6 ◽  
Author(s):  
T. D. Mangal ◽  
S. Paterson ◽  
A. Fenton
Keyword(s):  
Parasitic Infection ◽  
Egg Laying ◽  
High Density ◽  
Biomphalaria Alexandrina ◽  
Density Dependent ◽  
Snail Density ◽  
Negative Exponential Distribution ◽  
Survival Density ◽  
Negative Exponential ◽  
The Impact

The effects of snail density onBiomphalaria alexandrinaparasitized withSchistosoma mansoniwere investigated. Laboratory experiments were used to quantify the impact of high density on snail growth, fecundity, and survival. Density-dependent birth rates of snails were determined to inform mathematical models, which, until now, have assumed a linear relationship between density and fecundity. The experiments show that the rate of egg-laying followed a negative exponential distribution with increasing density and this was significantly affected by exposure to parasitic infection. High density also affected the weight of snails and survival to a greater degree than exposure to parasitic infection. Although snail growth rates were initially constrained by high density, they retained the potential for growth suggesting a reversible density-dependent mechanism. These experimental data can be used to parameterise models and confirm that snail populations are regulated by nonlinear density-dependent mechanisms.

Applications of CCEM to Environmental Health Problems

1985 ◽  
Vol 43 ◽  
pp. 102-103
Author(s):  
R. J. Lee ◽  
J. S. Walker
Keyword(s):  
Electron Microscopy ◽  
Image Analysis ◽  
Environmental Health ◽  
Computer Control ◽  
External Agent ◽  
External Agents ◽  
Computer Controlled ◽  
Primitive State ◽  
Textural Changes ◽  
General Aspects

Electron microscopy (EM), with the advent of computer control and image analysis techniques, is rapidly evolving from an interpretative science into a quantitative technique. Electron microscopy is potentially of value in two general aspects of environmental health: exposure and diagnosis.In diagnosis, electron microscopy is essentially an extension of optical microscopy. The goal is to characterize cellular changes induced by external agents. The external agent could be any foreign material, chemicals, or even stress. The use of electron microscopy as a diagnostic tool is well- developed, but computer-controlled electron microscopy (CCEM) has had only limited impact, mainly because it is fairly new and many institutions lack the resources to acquire the capability. In addition, major contributions to diagnosis will come from CCEM only when image analysis (IA) and processing algorithms are developed which allow the morphological and textural changes recognized by experienced medical practioners to be quantified. The application of IA techniques to compare cellular structure is still in a primitive state.

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