Changes in the haemolymph proteome of Spodoptera littoralis induced by the parasitoid Chelonus inanitus or its polydnavirus and physiological implications.
The egg-larval parasitoid Chelonus inanitus induces in its host Spodoptera littoralis two major developmental effects, namely a precocious onset of metamorphosis followed by a developmental arrest in the prepupal stage. Along with each egg, the wasp injects polydnavirus and venom into the host egg. The polydnavirus has been shown to play a major role in inducing the developmental arrest while the parasitoid larva is instrumental in inducing the precocious onset of metamorphosis. Here we report that experimental dilution of haemolymph of polydnavirus-containing larvae can partially prevent the developmental arrest while injection of native, but not of heat-treated, haemolymph or plasma from polydnavirus-containing larvae into nonparasitized larvae could induce developmental arrest in 14-15% of the larvae. This illustrates that heat-labile factors present in haemolymph play a role in causing developmental arrest. Injection of parasitoid medium increased the proportion of larvae entering metamorphosis precociously while injection of antibodies against a parasitoid-released protein had the opposite effect; this indicates that this protein and possibly other parasitoid-released substances are involved in inducing the precocious onset of metamorphosis. Analysis of the plasma proteome of nonparasitized, parasitized and polydnavirus-containing larvae revealed that the developmental effects are associated with only minor differences: eleven low abundant viral or virus-induced proteins and five parasitoid-released proteins were seen at specific stages of the host.
Kaeslin
Martha
M
Institute of Cell Biology, University of Berne, Baltzerstrasse 4, CH-3012 Bern, Switzerland.
Pfister-Wilhelm
Rita
R
Molina
Daniel
D
Lanzrein
Beatrice
B
D000818:Animals; D000914:Antibodies, Viral / Q000378:metabolism; D015536:Down-Regulation; D020869:Gene Expression Profiling; D006458:Hemolymph / Q000378:metabolism* / Q000528:radiation effects; D006790:Host-Parasite Interactions; D019476:Insect Proteins / Q000378:metabolism*; D008675:Metamorphosis, Biological / Q000502:physiology; D018071:Polydnaviridae / Q000502:physiology*; D018411:Spodoptera / Q000378:metabolism / Q000469:parasitology* / Q000528:radiation effects / Q000821:virology*; D014965:X-Rays
D000914:Antibodies, Viral; D019476:Insect Proteins