INTER- AND INTRASPECIFIC LARVAL COMPETITION IN APHIDIUS SMITHI AND PRAON PEQUODORUM (HYMENOPTERA: APHIDIIDAE)

1984 ◽  
Vol 116 (8) ◽  
pp. 1097-1107 ◽  
Author(s):  
F. J. Chow ◽  
M. Mackauer

AbstractSuperparasitism and multiple parasitism of the pea aphid, Acyrthosiphon pisum (Harris), by the solitary hymenopterous parasites Aphidius smithi Sharma & Subba Rao and Praon pequodorum Viereck were studied in the laboratory. In intraspecific competition, an older larva usually eliminated a younger one; exceptions to this rule depended on the relative age difference and developmental stage of the competitors. In interspecific competition, P. pequodorum was intrinsically superior to A. smithi, regardless of the latter's age. The stage of host parasitized and the number of competing larvae had no significant effect on the outcome of the contest. A. smithi females discriminated against aphids previously parasitized by a conspecific female or by P. pequodorum, the degree of oviposition restraint increasing with the time between ovipositions. P. pequodorum females attacked aphids already parasitized by A. smithi, regardless of the age of the Aphidius larva, but avoided oviposition when the aphid contained a Praon larva or embryo. The rate of embryonic development is shown as a major factor in contest-type competition between first-stage larvae.

1985 ◽  
Vol 117 (1) ◽  
pp. 133-134 ◽  
Author(s):  
F. J. Chow ◽  
M. Mackauer

Chow and Mackauer (1984) recently reported on inter- and intraspecific larval competition between Aphidius smithi Sharma & Subba Rao and Praon pequodorum Viereck (Hymenoptera: Aphidiidae), when both were parasitizing the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae). In interspecific competition, a 1st-instar Praon larva usually eliminated, by physical combat, an Aphidius larva that was up to 48 h older. However, circumstantial evidence suggested that once an Aphidius larva had reached an advanced stage of the final (4th) instar, it was able to complete development and pupate, even in the presence of a younger Praon competitor.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guang Wang ◽  
Jing-Jiang Zhou ◽  
Yan Li ◽  
Yuping Gou ◽  
Peter Quandahor ◽  
...  

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.


1983 ◽  
Vol 115 (12) ◽  
pp. 1615-1619 ◽  
Author(s):  
William D. Hutchison ◽  
David B. Hogg

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.


2006 ◽  
Vol 72 (3) ◽  
pp. 1956-1965 ◽  
Author(s):  
Anne-Marie Grenier ◽  
Gabrielle Duport ◽  
Sylvie Pagès ◽  
Guy Condemine ◽  
Yvan Rahbé

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.


Heredity ◽  
2002 ◽  
Vol 89 (5) ◽  
pp. 346-352 ◽  
Author(s):  
M C Caillaud ◽  
M Boutin ◽  
C Braendle ◽  
J-C Simon

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