In vivo Production of Palpita vitrealis Nucleopolyhedrovirus

A Preliminary bioassay was conducted to determine the suitable larval instar of the olive leaf moth, Palpita vitrealis (Rossi) and the needed concentration of its homologous baculovirus Palpita viteralis nucleopolyhedrovirus (PaviNPV) for in vivo production. The calculated lethal concentrations for killing 90% of the tested larvae (LC90) were 8.3×104, 15×104, 9.1×104 and 1.7×104 PIBs/ml for the tested 2nd, 3rd, 4th and 5th instars, respectively. In production tests, leaf-bud dipping bioassays were used for larvae infection. Virus yield of PaviNPV progeny polyhedral inclusion bodies (PIBs) was calculated in relation to the inoculum used for larval infection. The mortality rates of the tested PaviNPV concentrations (104-107 PIB’s/ml) against the tested fourth and fifth larval instars showed ascending mortality-concentration dependence. The productivity rate (folds) of PaviNPV in the case of the fourth instar larvae were 137000, 35540, 1471, and 134.8 folds for the tested inoculum concentrations of 104, 105, 106 and 107 PIBs/ml, respectively. The addition of fluorescent brightener 28 (Tinopal UNPA-GX) enhanced the mortality rate and the obtained PaviNPV progeny by 188800, 43600, 1333.2 and 177.66 folds for the same inoculum concentrations, respectively. The study suggests using the fourth instar Palpita vitrealis larvae with a PaviNPV concentration of 104 PIB’s/ml for in vivo production. Keywords: Palpita, olive leaf moth, production, alphabaculovirus.