THE EFFECT OF HOST DENSITY ON EGG DISTRIBUTION BY THE SOLITARY PARASITOID APHIDIUS NIGRIPES (HYMENOPTERA: APHIDIIDAE)

1984 ◽  
Vol 116 (6) ◽  
pp. 805-811 ◽  
Author(s):  
Conrad Cloutier
Keyword(s):  
Random Search ◽  
Host Density ◽  
Macrosiphum Euphorbiae ◽  
Type Ii ◽  
Ecological Significance ◽  
Egg Distribution ◽  
Aphidius Nigripes ◽  
Random Models ◽  
Solitary Parasitoid ◽  
Host Aphid

AbstractEgg distribution by the solitary parasitoid Aphidius nigripes was studied experimentally at 14 densities of the host aphid, Macrosiphum euphorbiae. The number of hosts parasitized increased with host density, the functional response being of Holling's type II. However the average number of eggs/female was not significantly affected by host density, and consequently superparasitism increased with decreasing host density. When egg distributions were tested against random models, higher than predicted numbers of both unparasitized and superparasitized hosts were observed at all densities tested. Further analysis assuming random search suggested that female A. nigripes tend to deposit several eggs per host while experiencing a low rate of encounter with hosts. The ecological significance of this behaviour is examined.

On the search for hosts and the egg distribution of some chalcid parasites of the knapweed gall-fly

Parasitology ◽  
1941 ◽  
Vol 33 (1) ◽  
pp. 47-66 ◽  
Author(s):  
G. C. Varley
Keyword(s):  
Small Area ◽  
Random Distribution ◽  
Random Search ◽  
Host Density ◽  
Oviposition Behaviour ◽  
Numerical Accuracy ◽  
Small Areas ◽  
Egg Distribution ◽  
First Approximation ◽  
Tentative Explanation

1. The egg distributions of five chalcid parasites of the knapweed gall-fly have been studied in a small area.2. A distinction is made between search for hosts by random movements, and random search in the sense of Nicholson; these terms are defined. Random movements may give rise to a distribution of parasitism different from that expected if search were purely random.3. The species discussed do not all distribute their eggs at random amongst the hosts. Some species superparasitize the hosts more, and one (Eurytoma curta) much less than would be expected if the egg distribution were purely random, owing to peculiarities in oviposition behaviour.4. Parasitism by E. curta is unevenly distributed in space, being higher in areas of high host density. This suggests that search is not exactly random, but is also concentrated in space. A tentative explanation is advanced based on the assumption that search is by random movements.5. Parasitism by E. robusta is very patchy. This non-random distribution is attributed to random movements performed by a very few parasites.6. It is concluded that these spatial discrepancies do not seriously affect the numerical accuracy of the assumption that search is random in small areas, and that the theory of Nicholson & Bailey may be accurate to a first approximation.

FECUNDITY, LONGEVITY, AND SEX RATIO OF APHIDIUS NIGRIPES (HYMENOPTERA: APHIDIIDAE) PARASITIZING DIFFERENT STAGES OF ITS HOST, MACROSIPHUM EUPHORBIAE (HOMOPTERA: APHIDIDAE)

1981 ◽  
Vol 113 (3) ◽  
pp. 193-198 ◽  
Author(s):  
Conrad Cloutier ◽  
Jeremy N. McNeil ◽  
Jacques Regnière
Keyword(s):  
Sex Ratio ◽  
Direct Relationship ◽  
Developmental Stages ◽  
Macrosiphum Euphorbiae ◽  
Separate Experiment ◽  
Female Parasite ◽  
Potato Aphid ◽  
Aphidius Nigripes ◽  
Host Stage ◽  
Female Longevity

AbstractThe longevity and age specific fecundity, as well as the sex ratio of the progeny, were obtained for Aphidius nigripes Ashmead females given access to the five developmental stages of the potato aphid, Macrosiphum euphorbiae (Thomas). Neither female longevity nor fecundity, as measured by the total number of aphids parasitized, were significantly different for the various host stages. The percentage of females in the progeny decreased as the female parasite aged, and the overall sex ratio of progeny was significantly affected by the host stage attacked although no direct relationship with host size was evident. However in a separate experiment where parasitism was controlled (females not permitted to attack more than 10 hosts per day), the host stage (size) significantly affected the sex ratio of progeny, with more females emerging from larger than smaller hosts.These data indicate that all developmental stages of M. euphorbiae, when presented separately, are suitable to A. nigripes.

scholarly journals Evolutionary Implications of Anoxygenic Phototrophy in the Bacterial Phylum Candidatus Palusbacterota (WPS-2)

2019 ◽  
Author(s):  
Lewis M. Ward ◽  
Tanai Cardona ◽  
Hannah Holland-Moritz
Keyword(s):  
Photochemical Reaction ◽  
Close Association ◽  
Reaction Centers ◽  
Phylogenomic Analysis ◽  
Metagenomic Sequencing ◽  
Type Ii ◽  
Ecological Significance ◽  
Anoxygenic Photosynthesis ◽  
New Family ◽  
Related Proteins

AbstractGenome-resolved environmental metagenomic sequencing has uncovered substantial previously unrecognized microbial diversity relevant for understanding the ecology and evolution of the biosphere, providing a more nuanced view of the distribution and ecological significance of traits including phototrophy across diverse niches. Recently, the capacity for bacteriochlorophyll-based anoxygenic photosynthesis has been found in the uncultured bacterial WPS-2 clade that are in close association with boreal moss. Here, we use phylogenomic analysis to investigate the diversity and evolution of phototrophic WPS-2. We demonstrate that phototrophic WPS-2 show significant genetic and metabolic divergence from other phototrophic and non-phototrophic lineages. The genomes of these organisms encode a completely new family of anoxygenic Type II photochemical reaction centers and other phototrophy-related proteins that are both phylogenetically and structurally distinct from those found in previously described phototrophs. We propose the name Candidatus Palusbacterota for the phylum-level aerobic WPS-2 clade which contains phototrophic lineages, from the Latin for “bog bacteria”, distinguishing it from the anaerobic, non-phototrophic sister phylum Candidatus Eremiobacterota for “desert bacteria”, typically found in dry environments.

Effects of Host Age and Density on the Performance of Apanteles hemara (Hymenoptera: Braconidae), a Larval Endoparasitoid of Spoladea recurvalis (Lepidoptera: Crambidae)

2019 ◽  
Vol 112 (5) ◽  
pp. 2131-2141
Author(s):  
S T O Othim ◽  
S Ramasamy ◽  
R Kahuthia-Gathu ◽  
T Dubois ◽  
S Ekesi ◽  
...  
Keyword(s):  
Functional Response ◽  
Development Time ◽  
Host Density ◽  
Mass Rearing ◽  
Developmental Period ◽  
Adult Longevity ◽  
Type Ii ◽  
Host Age ◽  
Parasitism Rate ◽  
Type Ii Functional Response

AbstractThe amaranth leaf-webber, Spoladea recurvalis (Fabricius; Lepidoptera: Crambidae), is a serious pest of Amaranthus sp. in Africa and Asia. Apanteles hemara (Nixon; Hymenoptera: Braconidae) is by far the most important larval endoparasitoid of the amaranth leaf-webber. We examined the effects of host density and age on the biological characteristics of A. hemara. The regression model of the number of hosts supplied to A. hemara against the number of larvae parasitized resulted in a curve corresponding to type II functional response, with a significant increase in the number of hosts parasitized up to the density of 30 hosts before being constant up to 40 hosts. In contrast, the parasitism rate decreased linearly with increasing host densities. Development time, sex ratio, and adult longevity were not significantly affected by host density. The immature parasitoid mortality was significantly higher at higher host densities. Apanteles hemara did not parasitize 7-d-old larvae and beyond, while parasitism was significantly higher among 1- to 2-d-old compared with 3- to 4-d-old larvae. Immature parasitoid mortality was 2.6 times higher in 1- to 2-d-old larvae compared with 5- to 6-d-old larvae. The developmental period of the parasitoid from egg to adult was longest among 1- to 2-d-old larvae and least among 5- to 6-d-old larvae. Nonreproductive mortality was markedly higher among 1- to 2-d-old larvae compared with the older larvae. Adult female A. hemara were significantly larger on 3- to 4-d-old larvae compared with either 1- to 2-d-old or 5- to 6-d-old larvae. We discuss the implications of our results for the interpretation of functional response in parasitoids, mass rearing, conservation, and augmentative biological control of S. recurvalis.

Host discrimination in the aphid parasitoid Aphidius nigripes

1984 ◽  
Vol 62 (7) ◽  
pp. 1367-1372 ◽  
Author(s):  
Conrad Cloutier ◽  
Lothar A. Dohse ◽  
France Bauduin
Keyword(s):  
Time Dependent ◽  
Macrosiphum Euphorbiae ◽  
Time Interval ◽  
Host Discrimination ◽  
Initial Attack ◽  
Aphid Parasitoid ◽  
Potato Aphid ◽  
Aphidius Nigripes ◽  
Best Fitting ◽  
Increasing Function

Females of the solitary aphid parasitoid Aphidius nigripes do not consistently avoid superparasitizing their hosts, the potato aphid Macrosiphum euphorbiae. Tests were conducted in which two attacks separated by a time interval ranging from 1 to 24 h were allowed per host. No evidence of host discrimination was found when the interval was <2 h. For longer intervals, host discrimination was an increasing function of the length of the interval up to 24 h after the initial attack. Various mathematical models, permitting time-related rejection of parasitized hosts, were used to simulate the parasitoids–host distributions following two attacks. The best fitting models also had to incorporate time-dependent discrimination against hosts that had been attacked but not successfully parasitized. The results are discussed with respect to possible mechanisms of host discrimination in A. nigripes and its significance in intraspecific competition.

scholarly journals Functional response and mutual interference of Diaeretiella rapae (Hymenoptera: Aphidiidae) on Brevicoryne brassicae (Homoptera: Aphididae)

2006 ◽  
Vol 17 (2) ◽  
pp. 90-97 ◽  
Author(s):  
Yaghoub Fathipour ◽  
Ali Hosseini ◽  
Ali Talebi ◽  
Saeid Moharramipour
Keyword(s):  
Logistic Regression ◽  
Functional Response ◽  
Host Density ◽  
Handling Time ◽  
Mutual Interference ◽  
Brevicoryne Brassicae ◽  
Least Square ◽  
Diaeretiella Rapae ◽  
Type Ii ◽  
Per Capita

Functional response and mutual interference are the most important behavioural characteristics that reveal different aspects of host–parasitoid interactions. In this study, functional response and mutual interference of the parasitoid wasp, Diaeretiella rapae (M’Intosh) attacking the cabbage aphid, Brevicoryne brassicae (Linnaeus) were investigated. Logistic regression was used to distinguish the shape of the functional response (type II or III). Nonlinear least-square regression was used to estimate the attack rate (a) and handling time (Th). Nicholson’s model and linear regression were used to determine per capita searching efficiency and interference coefficient, respectively. Logistic regression suggested a type II response on B. brassicae nymphs. The per capita parasitism decreased significantly from 80.80 (67.33%) to 11.85 (9.88%) as parasitoid densities increased from 1 to 8 females. Consequently, the per capita searching efficiency decreased significantly from 1.173 to 0.205 as parasitoid densities increased from 1 to 8. The rate of parasitism increased as the host density increased from 2 to 50, and subsequently the parasitoid density decreased from 8 to 1. Therefore, different host–parasitoid ratios could affect the efficacy of D. rapae.

scholarly journals Functional response of the predator Eriopis connexa (Coleoptera: Coccinellidae) to different prey types

2007 ◽  
Vol 50 (1) ◽  
pp. 121-126 ◽  
Author(s):  
Renato Almeida Sarmento ◽  
Angelo Pallini ◽  
Madelaine Venzon ◽  
Og Francisco Fonseca de Souza ◽  
Adrián José Molina-Rugama ◽  
...  
Keyword(s):  
Functional Response ◽  
Biological Control Agent ◽  
Control Agent ◽  
Macrosiphum Euphorbiae ◽  
Type Ii ◽  
Response Type ◽  
Tetranychus Evansi ◽  
Type Iii ◽  
Eriopis Connexa ◽  
Type Ii Functional Response

This work evaluated the functional response of adult females of Eriopis connexa to different densities of Macrosiphum euphorbiae and Tetranychus evansi. When preying upon aphids, E. connexa presented a sigmoidal functional response (Type III). This behavior, however, changed drastically to an exponential (Type II) functional response, when mites (T. evansi), rather than aphids, were offered to E. connexa. Such different patterns showed that this coccinellid needed to adopt distinct strategies according to the kind of prey available. Since predators were believed to be able to regulate prey populations only when adopting Type III functional response. E. connexa would be a good candidate for a biological control agent of M. euphorbiae, but would not suppress a growing population of T. evansi.

scholarly journals Functional response of Trichogramma pretiosum on Trichoplusia ni eggs at different temperatures and egg densities

2018 ◽  
Vol 53 (5) ◽  
pp. 641-645
Author(s):  
André Malacarne Milanez ◽  
José Romário de Carvalho ◽  
Victor Luiz Souza Lima ◽  
Dirceu Pratissoli
Keyword(s):  
Logistic Regression ◽  
Functional Response ◽  
Trichoplusia Ni ◽  
Host Density ◽  
Search Efficiency ◽  
Type Ii ◽  
Trichogramma Pretiosum ◽  
Parasitism Rate ◽  
Different Temperatures ◽  
Type Ii Functional Response

Abstract: The objective of this work was to determine the functional response of the parasitoid Trichogramma pretiosum on Trichoplusia ni eggs at different temperatures (20, 25, and 30ºC) and egg densities (5, 10, 15, 20, 25, and 30 eggs). The logistic regression showed a type-II functional response for all temperatures. The search efficiency of T. pretiosum was reported as 0.049±0.0019, 0.069±0.0042 and 0.068±0.0033 per hour, and the estimated handling times were 1.82±0.0424, 1.69±0.0398, and 1.54±0.0498 hour at 20, 25 and 30ºC, respectively. Females of Trichogramma pretiosum show greater efficiency at 30ºC and a type-II functional response. The parasitism rate decreases, when host density increases.

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