Remarkably efficient production of a highly insecticidal Chrysodeixis chalcites nucleopolyhedrovirus (ChchNPV) isolate in its homologous host.

BACKGROUNDA 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. RESULTSThe sixth instar (L-6) was the most suitable for virus production, producing 1.80 x 10(11) occlusion bodies (OB)/larva and showed a lower prevalence of cannibalism (5.4%) than fourth (L-4) or fifth (L-5) instars. Inoculation of L-6 at 24 h post molting produced six times more OB (5.72 x 10(11) OB/larva) than recently molted L-6 larvae (1.00 x 10(11) OB/larva). No significant differences were recorded in mean time to death (165-175 h) or OB production per larva (3.75 x 10(11) to 5.97 x 10(11)) or per mg larval weight (1.30 x 10(11) to 2.11 x 10(9)), in larvae inoculated with a range of inoculum concentrations (LC50-LC90). Groups of infected L-6 larvae reared at a density of 150 larvae/container produced a greater total number of OBs (8.07 x 10(13) OB/container) than lower densities (25, 50 and 100 OB/container), and a similar number to containers with 200 inoculated larvae (8.43 x 10(13) OB/container). CONCLUSIONThe processes described here allow efficient production of sufficient OBs to treat approximate to 40 ha of banana crops using the insects from a single container. (c) 2018 Society of Chemical Industry