Effects of infection with a granulosis virus on larval growth, development and ecdysteroid production in the cabbage looper, Trichoplusia ni |
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| Authors: | E M DOUGHERTY T J KELLY R ROCHFORD J A FORNEY J R ADAMS |
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| Institution: | U.S. Department of Agriculture, Agricultural Research Service (Insect Pathology Laboratory, Beltsville, Maryland;*Insect Reproduction Laboratory), Beltsville, Maryland |
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| Abstract: | ABSTRACT. Granulosis virus-infected Trichoplusia ni (Hûbner) larvae exhibited an increased larval life span with no supernumerary moult and no pupation. Weight gain was not affected. Insects infected shortly after hatching were slower in reaching the fourth and fifth stadia than were control insects. Haemolymph ecdysteroid titres were lower in virus-infected insects than control insects, but these differences were only significant ( P <0.05) in the fifth stadium. Electron microscopic examination of the pro thoracic glands revealed extensive granulosis virus infection, and glands from virus-infected insects produced no RIA-detectable ecdysteroids in vitro. Injection of 20-OII-ecdysone into virus-infected larvae at various concentrations and times did not induce pupation. |
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| Keywords: | Granulosis virus prothoracic gland ecdysteroids moulting pupation Trichoplusia ni |
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