To eat or not to eat: Garcinia kola (Clusiaceae) modifies the behavior of Colorado potato beetle, Leptinotarsa decemlineata (Say)

Colorado potato beetle (CPB), Leptinotarsa decemlineata (Coleoptera: Chrysomelidae), is a key pest of cultivated potato, Solanum tuberosum (Solanaceae). The beetle is capable of evolving resistance to multiple classes of insecticides within a few generations, posing serious challenge to conventional control practice, thus warranting continual search for novel weapons. Non-synthetic biopesticides show promise but remain poorly explored; hence, seed extract of Garcinia kola, a tropical tree crop commonly known as bitter kola in West Africa, was tested at variable doses of no-choice (feeding) and dual-choice leaf-disc bioassays for antifeedant and preference using four methanolic concentrations: stock (0.2 g/ml), high (0.1 g/ml) and mild (0.05 g/ml) and low (0.01 g/ml) and were set up in a randomized complete block design. Results from the dual choice assays showed that the insect larvae and adults significantly avoided feeding on leaves treated with stock, high and medium treatments, but caused comparable damage on low-concentration-treated leaves as they did to control. In no choice trials, most of the treated leaves showed significantly greater feeding deterrence across the larval stages and adults, with markedly less damage on the treated leaves than untreated controls. In sum, methanolic extract of G. kola’s seed has promising behavior-modifying properties that could be useful in managing the Colorado potato beetle and allied pests in potato cropping systems, especially in organic farms or systems where synthetic chemicals may affect non-target species.