2017 ASHS Annual Conference

Development of cold-tolerant banana cultivars provide potential for the establishment of a non-Cavendish banana niche market in coastal Alabama. The Japanese beetle (Popillia japonica) a highly polyphagous, invasive insect was established in coastal Alabama recently and threatens establishment of a banana niche market. Upon field observations, it was noted that Japanese beetle (JB) selection of banana leaves as a food source might be influenced by cultivar. The goal of this study was to determine if cultivar plays a role in JB herbivory of banana leaves using both lab choice studies and field assessment. Least square means comparisons using Shaffer-simulated method at α = 0.05 with cultivar as the main effect were used (SAS 9.4). Trends over rating dates were determined using qualitative-quantitative regression models in field evaluations. In the lab choice test, leaf thickness (µm) was determined from harvested leaf sections (30 cm x 10 cm) using a Mitutoyo Digimatic Indicator. Leaf discs (25 mm in diameter) were cut from banana leaf section from the following cultivars: Cacambou’, ‘Ice Cream’ (‘Blue Java’), ‘Kumunaba’, ‘Raja Puri’, ‘Sweetheart’, and ‘Willims’. Treatments consisted of six replications using a completely randomized design. Weights of leaf discs were recorded and surface areas were determined using ImageJ image processing program. Two leaf discs, from two different banana cultivar, were anchored to the wax-coated bottom of a feeding arena with straight pins. Two female JB were placed in the feeding arenas and were allowed to feed for 4 hours or until approximately 50% of the choice, leaf disc had been consumed. This process was repeated until all possible pair combinations were made. Ratings of JB feeding damage in the field based on percent leaf area consumed were recorded. In the lab choice test JB demonstrated a preference for ‘Kumunaba’ banana leaf tissue (0.17 mg·mm²). This preference was statistically similar to JB preference for ‘Sweetheart’ banana leaf tissue (0.16 mg·mm²). In field ratings, ‘Belle’ bananas sustained the most damage from JB feeding (9.0 %); however, damage sustained by JB feeding was statistically similar to damage sustained by ‘Kumunaba’ (5.5 %) and ‘Williams’ (5.0 %) banana leaves. Preference for leaves of ‘Kumunaba’ bananas was significant in both lab choice and field ratings. Leaves of ‘Belle’ bananas were among those most often consumed by JB in the field but were among the least often selected in the lab choice test.