Effect of starvation upon baculovirus replication in larval Bombyx mori and Heliothis virescens

The progression of baculovirus (BmNPV, BmCysPD, AcMNPV or AcAaIT) infection in larval Bombyx mori and Heliothis virescens (1st, 3rd or 5th instar) was investigated following various starvation regimes. When the larvae were starved for 12 or 24h immediately following inoculation, the median lethal time to death (LT(50)) was delayed by 9.5-19.2h in comparison to non-starved controls. This corresponded to a delay of 10-23% depending upon the larval stage and virus that was used for inoculation. When a 24h-long starvation period was initiated at 1 or 2 days post inoculation (p.i.), a statistically significant difference in LT(50) was not found indicating that the early stages of infection are more sensitive to the effects of starvation. Viral titers in the hemolymph of 5th instar B. mori that were starved for 24h immediately following inoculation were 10-fold lower (p<0.01) than that found in non-starved control larvae. Histochemical analyses indicated that virus transmission was reduced in 5th instar B. mori that were starved for 24h immediately following inoculation in comparison to non-starved control larvae. In general, the mass of larvae that were starved immediately after inoculation was 30% lower than that of non-starved control insects. Our findings indicate that starvation of the larval host at the time of baculovirus exposure has a negative effect on the rate baculovirus transmission and pathogenesis.