Abstract Description

The integrated pest management program for False Codling Moth (Thaumatotibia leucotreta, FCM) in South Africa relies heavily on Cryptophlebia leucotreta granulovirus-SA (CrleGV-SA) as a biopesticide. Limitations in CrleGV-SA application, evolving EU regulations, and inherent challenges with baculovirus biopesticides necessitate novel strategies. Dual baculovirus infections can lower lethal concentrations, but competition for host resources often prolongs lethal time. Viral enhancins, extracellular proteins that increase viral pathogenicity, are a promising alternative. Studies with Lymantria dispar MNPV, Autographa californica MNPV, and Trichoplusia ni GV (TnGV) enhancins showed increased potency, faster LT₅₀, and higher toxicity. This study investigates a TnGV enhancin protein, expressed in yeast, to enhance CrleGV-SA infectivity against T. leucotreta. Bioinformatic analysis characterized the TnGV enhancin protein, focusing on transmembrane domains and topology. The synthetic gene was PCR-amplified, cloned into an expression vector, and transformed into yeast. Protein expression was initially assessed by antibody detection, with samples submitted for mass spectrometry confirmation. Bioassays used FCM neonates with a constant LC₅₀ of 2 × 10⁴ OBs/larva of CrleGV-SA combined with three protein doses: 10, 40, and 70 ng/larva. Although not yet conclusively identified, the observed protein fits expected criteria: secreted, soluble, and matching predicted size. It was detected in only 2 of over 90 yeast transformants, indicating rare but specific expression. Antibody detection still under troubleshooting, and mass spectrometry confirmation will be delayed, so bioassays were performed with the suspected protein. Bioassays are mid completion, and statistical analysis is underway to assess the protein’s effect on virus infectivity. This study demonstrates critical progress in expressing and functionally assessing the TnGV enhancin protein for use with CrleGV-SA. Successful cloning, rare but promising detection of the expected protein, and completed bioassays represent key milestones toward establishing the protein’s role in improving viral efficacy. Pending mass spectrometry confirmation and statistical validation of bioassay outcomes will clarify the enhancin’s impact on CrleGV-SA lethal concentration (LC₅₀) and lethal time (LT₅₀). Optimizing yeast-based production and confirming biological effects could provide an important advance in enhancing baculovirus-based biopesticides for sustainable FCM control in South Africa.