Stage‐specific insecticidal characteristics of a nucleopolyhedrovirus isolate from Chrysodeixis chalcites enhanced by optical brighteners

Background Chrysodeixis chalcites is a major noctuid pest of banana crops in the Canary Islands. The stage‐specific susceptibility of this pest to C. chalcites single nucleopolyhedrovirus ( ChchSNPV‐TF1 ) was determined, as well as the effect of selected optical brighteners as enhancers of primary infection . Results Susceptibility to ChchSNPV‐TF1 occlusion bodies ( OBs ) decreased as larval stage increased; second instars ( L 2 ) were 10 000‐fold more susceptible than sixth instars ( L 6 ). Virus speed of kill was 42 h faster in L 2 than in L 6 . OB production increased in late instars; L 6 larvae produced 23‐fold more OBs than L 4 . Addition of 10 mg  mL −1 Tinopal enhanced OB pathogenicity by 4.43‐ to 397‐fold depending on instar, whereas 10  µL mL −1 Leucophor resulted in potentiation of OB pathogenicity from 1.46‐ to 143‐fold. Mean time to death decreased by 14 to 26 h when larvae consumed OBs in mixtures with 10 mg  mL −1 Tinopal, or 10  µL mL −1 Leucophor, although in these treatments OB yields were reduced by up to 8.5‐fold (Tinopal) or up to 3.8‐fold (Leucophor) . Conclusion These results have clear applications for the use of ChchSNPV‐TF1 as a biological insecticide in control programs against C. chalcites in the Canary Islands. © 2013 Society of Chemical Industry