SELF-SUPERPARASITISM IN THE SOLITARY PARASITOID MONOCTONUS PAULENSIS (HYMENOPTERA: BRACONIDAE, APHIDIINAE): PROXIMATE MECHANISMS

1999 ◽  
Vol 131 (6) ◽  
pp. 769-777 ◽  
Author(s):  
Amanda Chau ◽  
Manfred Mackauer
Keyword(s):  
Clutch Size ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Proximate Mechanisms ◽  
Host Instar ◽  
Egg Number ◽  
Solitary Parasitoid

AbstractMonoctonus paulensis (Ashmead) was reared in the laboratory on the four nymphal instars of the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea: Aphididae). Females frequently laid clutches of two eggs during a single ovipositor probe; however, clutches of more than two eggs were rare. The time needed to capture and position an aphid for oviposition increased with aphid instar but was independent of the number of eggs laid. Oviposition time was proportional to egg number, which shows that eggs were laid one at a time rather than clumped together as a package. Intensity of parasitism (i.e., number of eggs per parasitized host) increased with host instar but declined with the number of hosts attacked in quick succession. Our results suggest that clutch size in M. paulensis is not accidental but controlled by the female.

Host–instar selection in the aphid parasitoid Monoctonus paulensis (Hymenoptera: Braconidae, Aphidiinae): assessing costs and benefits

2001 ◽  
Vol 133 (4) ◽  
pp. 549-564 ◽  
Author(s):  
Amanda Chau ◽  
Manfred Mackauer
Keyword(s):  
Body Size ◽  
Acyrthosiphon Pisum ◽  
Search Time ◽  
Pea Aphid ◽  
Potential Fecundity ◽  
Aphid Parasitoid ◽  
Offspring Number ◽  
Host Instar ◽  
Parasitoid Development ◽  
Pupal Mortality

AbstractFemales of Monoctonus paulensis (Ashmead), a solitary parasitoid of aphids, generally select the relatively smaller over equally available larger instars of the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea: Aphididae). Large hosts contain more resources for parasitoid development and hence have presumably higher quality; however, they require more time to subdue and are more likely to escape. We tested the hypothesis that a female’s choice among first (L1), second (L2), third (L3), and fourth (L4) instars of the pea aphid is based on the optimal balance between fitness costs in terms of time and fitness gains in terms of offspring number and size. Prepupal mortality did not vary with host instar, but pupal mortality was greater among parasitoids developing in L4 than in any younger instars. Offspring mortality was not influenced by clutch size in that mortality risk did not differ between parasitoids developing alone and counterparts developing in a clutch. The sex ratio, measured as proportion of daughters among offspring, was female-biased on all four host instars; the degree of bias increased from 0.70 (in L1) to 0.92 (in L4). Parasitoid body size was a function of aphid size at parasitism. Females were larger than males; the magnitude of the difference in body size was constant and independent of host and hence parasitoid size. A female’s potential fecundity as measured by the number of ovarial eggs at eclosion varied with her size and larval ontogeny. The four instars of the pea aphid were ranked in the order L1 > L2 > L3 > L4 both in terms of the number of offspring produced per encountered host and in terms of a female’s time costs; first instars are easier to handle and are more abundant in the field than older instars. The four host types were ranked in the order L2 > L3 > L1 > L4 in terms of the proportion and potential fecundity of daughters among offspring. The observed preference pattern (L1 > L2 > L3 > L4) suggests that, in choosing hosts, females of M. paulensis maximize the number of offspring per unit of search time rather than simply offspring quality.

DISCRIMINATION BETWEEN SELF- AND CONSPECIFIC-PARASITIZED HOSTS IN THE APHID PARASITOID PRAON PEQUODORUM VIERECK (HYMENOPTERA: APHIDIIDAE)

1993 ◽  
Vol 125 (5) ◽  
pp. 957-964 ◽  
Author(s):  
T.P. Danyk ◽  
M. Mackauer
Keyword(s):  
Conditional Probability ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Host Quality ◽  
Host Discrimination ◽  
Aphid Parasitoid ◽  
Type Host ◽  
Host Type ◽  
Solitary Parasitoid ◽  
Preference Tests

AbstractWe evaluated host discrimination and oviposition restraint in the wasp Praon pequodorum Viereck, a solitary parasitoid of the pea aphid, Acyrthosiphon pisum (Harris). In dichotomous preference tests, wasps attacked more unparasitized than equally available parasitized aphids, and more self-parasitized aphids than aphids parasitized by conspecific females. The conditional probability of a female laying an egg into an attacked aphid was independent of the host type. Host discrimination apparently involves a volatile and individual-specific pheromone marker. Females expecting to compete with other (conspecific) wasps for a limited host supply may ensure possession of the host by self superparasitism. Because host examination requires considerably more time than oviposition in P. pequodorum (and eggs contain few resources), it may be adaptive for a female to lay an egg in an examined host regardless of variations in host quality.

THE NUTRITIONAL ECOLOGY OF A PARASITOID WASP, EPHEDRUS CALIFORNICUS BAKER (HYMENOPTERA: APHIDIIDAE)

1993 ◽  
Vol 125 (3) ◽  
pp. 423-430 ◽  
Author(s):  
R. Sequeira ◽  
M. Mackauer
Keyword(s):  
Development Time ◽  
Sexual Size Dimorphism ◽  
Acyrthosiphon Pisum ◽  
Parasitoid Wasp ◽  
Nutritional Ecology ◽  
Dry Mass ◽  
Nymphal Instar ◽  
Size Dimorphism ◽  
Host Instar ◽  
Solitary Parasitoid

AbstractWe tested the hypothesis that the pattern of development and growth of a generalist parasitoid wasp varies in different hosts. We reared Ephedras californicus Baker (Hymenoptera: Aphidiidae), a solitary parasitoid of aphids, under controlled laboratory conditions on five kinds of hosts: nymphal instar 1 (24 h old), 2 (42 h), 3 (96 h), and 4 (144 h) of apterous virginoparae of Acyrthosiphon pisum (Harris), and nymphal instar 1 (24 h) of Macrosiphum creelii Davis (Homoptera: Aphididae). Parasitoid dry mass increased with the host instar at parasitization. Females were larger than males although the degree of sexual size dimorphism declined with increased host size. Development time from oviposition to adult eclosion varied non-linearly with the host instar at parasitization, and was shortest in first and fourth nymphal instars. Parasitoids developing in M. creelii gained more mass in less time than their counterparts developing in A. pisum of the same initial size. In low-quality hosts, parasitoids apparently trade off increased development time for a gain in adult mass. A possible explanation of sexual size dimorphism in E. californicus is that large females may be able to overcome aphid defensive behaviours better than small ones.

scholarly journals Trehalose and glucose levels regulate feeding behavior of the phloem-feeding insect, the pea aphid Acyrthosiphon pisum Harris

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guang Wang ◽  
Jing-Jiang Zhou ◽  
Yan Li ◽  
Yuping Gou ◽  
Peter Quandahor ◽  
...  
Keyword(s):  
Feeding Behavior ◽  
Growth And Development ◽  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Feeding Time ◽  
Electrical Penetration Graph ◽  
Glucose Content ◽  
Glucose Levels ◽  
Phloem Feeding ◽  
Trehalose Content

AbstractTrehalose serves multifarious roles in growth and development of insects. In this study, we demonstrated that the high trehalose diet increased the glucose content, and high glucose diet increased the glucose content but decreased the trehalose content of Acyrthosiphon pisum. RNA interference (RNAi) of trehalose-6-phosphate synthase gene (ApTPS) decreased while RNAi of trehalase gene (ApTRE) increased the trehalose and glucose contents. In the electrical penetration graph experiment, RNAi of ApTPS increased the percentage of E2 waveform and decreased the percentage of F and G waveforms. The high trehalose and glucose diets increased the percentage of E2 waveform of A. pisum red biotype. The correlation between feeding behavior and sugar contents indicated that the percentage of E1 and E2 waveforms were increased but np, C, F and G waveforms were decreased in low trehalose and glucose contents. The percentage of np, E1 and E2 waveforms were reduced but C, F and G waveforms were elevated in high trehalose and glucose contents. The results suggest that the A. pisum with high trehalose and glucose contents spent less feeding time during non-probing phase and phloem feeding phase, but had an increased feeding time during probing phase, stylet work phase and xylem feeding phase.

CORNICLE LENGTH AS A CRITERION FOR SEPARATING FIELD-COLLECTED NYMPHAL INSTARS OF THE PEA APHID, ACYRTHOSIPHON PISUM (HOMOPTERA: APHIDIDAE)

1983 ◽  
Vol 115 (12) ◽  
pp. 1615-1619 ◽  
Author(s):  
William D. Hutchison ◽  
David B. Hogg
Keyword(s):  
Acyrthosiphon Pisum ◽  
Pea Aphid ◽  
Field Sample ◽  
Rearing Temperature ◽  
Multimodal Analysis

AbstractCornicle length measuremetns of Acyrthosiphon pisum (Harris) nymphs reared in the laboratory were instar-specific and unaffected by rearing temperature. A multimodal analysis of cornicle lengths of field-collected aphids clearly detected four distribution peaks (i.e., instars) in five different field populations, and there was generaaly little overlap between successive instar distributions. However, third and fourth instars in the spring field sample could not be separated accurately due to the shorter cornicle length of nymphs that developed from overwintered eggs. Cornicle length proved to be a useful criterion for separating virginoparous A. pisum instars in samples collected in southern Wisconsin.

scholarly journals The Phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) Is a Pathogen of the Pea Aphid

2006 ◽  
Vol 72 (3) ◽  
pp. 1956-1965 ◽  
Author(s):  
Anne-Marie Grenier ◽  
Gabrielle Duport ◽  
Sylvie Pagès ◽  
Guy Condemine ◽  
Yvan Rahbé
Keyword(s):  
Acyrthosiphon Pisum ◽  
Ecological Impact ◽  
Sitophilus Oryzae ◽  
Pea Aphid ◽  
Erwinia Chrysanthemi ◽  
Future Research ◽  
Close Relative ◽  
Bacterial Cells ◽  
Dickeya Dadantii ◽  
Phytopathogenic Bacterium

ABSTRACT Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.

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