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Granulovirus prevents pupation and retards development of Adoxophyes honmai larvae
Author(s) -
Nakai Madoka,
Goto Chie,
Shiotsuki Takahiro,
Kunimi Yasuhisa
Publication year - 2002
Publication title -
physiological entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.693
H-Index - 57
eISSN - 1365-3032
pISSN - 0307-6962
DOI - 10.1046/j.1365-3032.2002.00282.x
Subject(s) - biology , ecdysteroid , hemolymph , larva , juvenile hormone , lepidoptera genitalia , metamorphosis , galleria mellonella , pupa , botany , microbiology and biotechnology , gene , genetics , virulence
Larvae of Adoxophyes honmai (Lepidoptera: Tortricidae) infected with granulovirus (AdhoGV) do not pupate; instead, they undergo prolonged larval development and die during the final stadium. Non‐infected larvae, however, pupate after five larval stadia. Insect metamorphosis is regulated by fluctuations of ecdysteroid and Juvenile Hormone (JH). JH esterase activity and titres of ecdysteroid must be measured to understand fully the interaction of an insect virus and its host. JH esterase activity is consistently low in AdhoGV‐infected larvae, which suggests that JH in AdhoGV‐infected larvae is not degraded during the final stadium. The ecdysteroid titre in non‐infected larvae showed a large peak in the final stadium before pupation, whereas that in AdhoGV‐infected larvae increased from day 2 to day 5 in the final stadium, and then remained at a high level until death. Furthermore, an ecdysteroid UDP‐glucosyltransferase (EGT) assay showed that this activity occurs in haemolymph from AdhoGV‐infected larvae, but not in haemolymph of non‐infected larvae. PCR and sequencing analysis revealed that the AdhoGV genome contains an egt gene, which encodes a protein of 445 amino acids, located approximately 1 kbp upstream from the granulin gene. These results suggest that AdhoGV‐infected larvae are prevented from pupating because JHE activity is suppressed and EGT expression inactivates ecdysteroid in the haemolymph.