Response behavior of stingless bee Tetragonula pagdeni and tobacco beetle Lasioderma serricorne to odorants

Abstract

Insect attractants presently play an important role in agriculture for increasing crop yields and decreasing loss of stored products. Pheromones and plant-derived volatiles are the effective odorants for attracting insect in both pre- and post-harvest managements. The use of trail pheromone of stingless bee in pre-harvest crop may affect on their pollination in crop field, while plant-derived volatiles may help to attract storage insect pest into trap when combined with their sex pheromone. This study aims to analyze the trail-scent compounds from labial glands of Tetragonula pagdeni, a common stingless bee of Thailand, for pre-harvest use, and to find plant-derived volatiles that act as kairomone attractant to Lasioderma serricorne, an important insect pest, in use for post-harvest products. For pre-harvest study, six hydrocarbons were detected in labial gland extract of T. pagdeni. Among these, three unidentified compounds appeared in scent-marked filter paper extract which the stingless bee rub on it, and one of them displayed the trail-following attractant to this species. This possible trail scent was the compound in peak no.2 that might be the unsaturated hydrocarbon with short chain compound. Further characterization of this compound could be necessary to confirm its behavioral activity. For post-harvest study, mulberry leaf tea had the highest attractive activity to L. serricorne among 30 plants tested. Thirteen volatile compounds containing in this tea were analyzed by headspace-SPME-GC-MS method. Phytol, β-ionone and methyl palmitate were the main volatile constituents. β-Ionone exhibited the highest attractive activity to L. serricorne, with 60% response index at 0.001 mg dose, while phytol, the major component, showed low attractive activity. However β-ionone did not show significantly different to commercial kairomone lure. The combination of phytol and β-ionone did not show the synergistic activity. This research is the first report in Thailand about the use of odorants from mulberry leaf tea to attract L. serricorne, and odorous compound from labial gland as trail pheromone for attracting T. pagdeni to food source. These might be the promising alternative tools for pre- and post-harvest managements that are suitable at least in Thailand.