Raspberry Ketone Analogs: Vapour Pressure Measurements and Attractiveness to Queensland Fruit Fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae)

The Queensland fruit fly, Bactrocera tryoni (Froggatt) (Q-fly), is a major horticultural pest in Eastern Australia. Effective monitoring, male annihilation technique (MAT) and mass trapping (MT) are all important for control and require strong lures to attract flies to traps or toxicants. Lure strength is thought to be related in part to volatility, but little vapour pressure data are available for most Q-fly lures. Raspberry ketone (4-(4-hydroxyphenyl)-2-butanone) and analogs that had esters (acetyl, difluoroacetyl, trifluoroacetyl, formyl, propionyl) and ethers (methyl ether, trimethylsilyl ether) in replacement of the phenolic group, and in one case also had modification of the 2-butanone side chain, were measured for their vapour pressures by differential scanning calorimetry (DSC), and their attractiveness to Q-fly was assessed in small cage environmentally controlled laboratory bioassays. Maximum response of one category of compounds, containing both 2-butanone side chain and ester group was found to be higher than that of the other group of compounds, of which either of 2-butanone or ester functionality was modified. However, linear relationship between vapour pressure and maximum response was not significant. The results of this study indicate that, while volatility may be a factor in lure effectiveness, molecular structure is the dominating factor for the series of molecules investigated.

昆士兰实蝇（Queensland fruit fly，学名：Bactrocera tryoni (Froggatt)，简称Q-fly）是澳大利亚东部地区的重大园艺害虫。有效的监测、雄性歼灭技术（male annihilation technique, MAT）与大量诱捕（mass trapping, MT）均是该害虫防控的关键环节，此类防控手段均需依托高效引诱剂将实蝇诱集至诱捕装置或毒剂中。学界普遍认为，引诱剂的效力在一定程度上与其挥发性相关，但目前绝大多数Q-fly引诱剂的蒸气压数据仍较为匮乏。本研究针对覆盆子酮（raspberry ketone，化学名：4-(4-羟苯基)-2-丁酮）及其衍生物展开测试：部分衍生物以酯基（乙酰基、二氟乙酰基、三氟乙酰基、甲酰基、丙酰基）与醚基（甲基醚、三甲基硅基醚）替换其酚羟基，另有一类衍生物同时对2-丁酮侧链进行了修饰；研究采用差示扫描量热法（differential scanning calorimetry, DSC）测定了上述化合物的蒸气压，并在小型可控环境实验室的笼养生物测定中评估了其对Q-fly的引诱活性。研究发现，一类同时保留2-丁酮侧链与酯基官能团的化合物，其最大引诱响应显著高于另外两组分别修饰了2-丁酮侧链或酯基官能团的化合物。然而，蒸气压与最大引诱响应之间并未呈现显著的线性相关关系。本研究结果表明，尽管挥发性可能是影响引诱剂效力的因素之一，但在所测试的化合物系列中，分子结构才是主导引诱活性的决定性因素。