Remarkably efficient production of a highly insecticidal Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV)...

A Chrysodeixis chalcites nucleopolyhedrovirus from the Canary Islands (ChchNPV-TF1) has proved to be effective for control of Chrysodeixis chalcites on banana crops. Commercialization of this virus as a bioinsecticide requires an efficient production system.

The sixth instar (L₆ ) was the most suitable for virus production, producing 1.80 × 10¹¹ occlusion bodies (OB)/larva and showed a lower prevalence of cannibalism (5.4%) than fourth (L₄ ) or fifth (L₅ ) instars. Inoculation of L₆ at 24 h post molting produced six times more OB (5.72 × 10¹¹ OB/larva) than recently molted L₆ larvae (1.00 × 10¹¹ OB/larva). No significant differences were recorded in mean time to death (165-175 h) or OB production per larva (3.75 × 10¹¹ to 5.97 × 10¹¹ ) or per mg larval weight (1.30 × 10¹¹ to 2.11 × 10⁹ ), in larvae inoculated with a range of inoculum concentrations (LC₅₀ -LC₉₀ ). Groups of infected L₆ larvae reared at a density of 150 larvae/container produced a greater total number of OBs (8.07 × 10¹³ OB/container) than lower densities (25, 50 and 100 OB/container), and a similar number to containers with 200 inoculated larvae (8.43 × 10¹³ OB/container).

The processes described here allow efficient production of sufficient OBs to treat ∼ 40 ha of banana crops using the insects from a single container. © 2018 Society of Chemical Industry.