An entomopoxvirus and a granulovirus use different mechanisms to prevent pupation of Adoxophyes honmai.
Adoxophyes honmai larvae inoculated with 10x the 95% lethal concentration of an entomopoxvirus (AdhoEPV) did not pupate, underwent a prolonged larval stage, and died during their final instar, unlike non-infected larvae which pupated after five larval instars. In previous work we showed that a granulovirus (AdhoGV) also retarded host development and prevented pupation of A. honmai larvae. In this study, endocrinological alterations in AdhoEPV-infected larvae were compared to those in AdhoGV-infected larvae. AdhoEPV-infected larvae had no peak of juvenile hormone (JH) esterase activity during the final instar, suggesting that JH titers in virus-infected larvae remained high during this period. In AdhoEPV-infected larvae the ecdysteroid titer remained low during the final instar, whereas in AdhoGV-infected larvae it peaked during the final instar and remained high towards the later stages of this instar. Ecdysteroid UDP-glucosyltransferase (EGT) activity was detected in the hemolymph of AdhoGV-infected A. honmai larvae, suggesting that the ecdysteroid would be inactivated in these insects. No EGT activity was detected in the hemolymph of either AdhoEPV-infected or non-infected A. honmai larvae. Thus, while AdhoEPV and AdhoGV both prevent pupation of A. honmai larvae, the mechanisms by which they do so appear to be different.
Nakai
Madoka
M
Department of Applied Biological Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Saiwai, Fuchu, Tokyo 183-8509, Japan. madoka@cc.tuat.ac.jp
Shiotsuki
Takahiro
T
Kunimi
Yasuhisa
Y
D000818:Animals; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D026461:Ecdysteroids / Q000032:analysis; D017996:Entomopoxvirinae / Q000472:pathogenicity*; D005964:Glucosyltransferases / Q000097:blood; D025722:Granulovirus / Q000472:pathogenicity*; D006458:Hemolymph / Q000737:chemistry; D007814:Larva / Q000254:growth & development / Q000821:virology; D007915:Lepidoptera / Q000254:growth & development* / Q000821:virology*; D008675:Metamorphosis, Biological; D011679:Pupa / Q000254:growth & development / Q000821:virology
D026461:Ecdysteroids; D005964:Glucosyltransferases; C086659:ecdysteroid UDP-glucosyltransferase; D002265:Carboxylic Ester Hydrolases; C038003:juvenile hormone esterase