Effects Of Aggregation Pheromone And Plant Volatiles On The Behavior Of Major Vegetable Thrips

Thrips,which is the common name of insects from order Thysanoptera,are minute insects mainly distributed in tropical and temperate regions.The most serious thrips pests in agriculture are Frankliniella occidentalis,Frankliniella intonsa,Thrips palmi,Megalothrips usitatus,etc.Thrips use rasping mouthparts to absorb nutrients from plant tissues,causing damage to crops.In addition,they could transmit a variety of plant viruses,such as tomato spotted wilt virus.Currently,the control of thrips pests is heavily reliant on the application of pesticides.However,the overuse of pesticides has led to the development of insecticide resistance in many thrips species.Moreover,the extensive use of chemical pesticides has caused serious threat to environment,food safety and human health.Compared with traditional chemical control,the thrips attractant based on aggregation pheromone and plant volatiles has the advantages of high efficiency,safety,non-toxicity,no pollution to the environment,and no harm to natural enemies.It can also be combined with other control stratiges,and is an important control method in the framework of integrated pest management(IPM).However,there are few studies to investigatewhether the interactions between thrips aggregation pheromone and plant attractants affect the attractive activities to thrips.In this study,the attractive doses of aggregation pheromone and plant volatiles were determined for F.occidentalis,F.intonsa,T.palmi,M.usitatus using Y tube olfacometerbioaasys.Then the effects of aggregation pheromone and plant volatiles mixtures on thrips behaviors were investigated for the four thrips species.There sults showed effects of mixtures varies among different species and mixture combinations,elicited antagonistic,synergistic or neutral effects when compared with single compound.The results of the study are as follows:1.The effects of aggregation pheromone and plant volatiles mixtures on the behavior of F.occidentalis: 500 ng F.occidentalis aggragation pheromone compound neryl(S)-2-methylbutanoate,0.001 μL eugenol,1 μL linalool,0.001 μL(-)-verbenone,0.1 μL p-anisaldehyde and 1μL methyl isonicotinate showed significant attractive activities to F.occidentalis.When mixed the aggeration pheromone with eugenol,linalool,(-)-verbenone and p-anisaldehyde,respectively,there were antagonistic effects,the mixtures showed no attractive activities to F.occidentalis.By contrast,when mixed the aggeration pheromone with methyl isonicotinate,the mixture showed attractive activities to F.occidentalis,but did not have synergistic effect compared with single compound.2.The effects of aggregation pheromone and plant volatiles mixtures on the behavior of T.palmi: 500 ng T.palmi aggragation pheromone compound(R)-lavandulyl3-methyl-3-butenoate,0.01 μ L linalool,0.01 μ L(-)-verbenone and 0.1 μ L p-anisaldehyde showed significant attractive activities to T.palmi.When mixed the aggeration pheromone with p-anisaldehyde,there was antagonistic effect,the mixture showed no attractive activities to T.palmi.When mixed the aggeration pheromone with(-)-verbenone,the mixture showed attractive activities to T.palmi,but did not have synergistic effect compared with single compound.When mixed the aggeration pheromone with linalool,the mixture showed attractive activities to T.palmi,and synergistic effect were found when compared with single compound.3.The effects of aggregation pheromone and plant volatiles mixtures on the behavior of M.usitatus: 50 ng M.usitatus aggragation pheromone compound(E,E)-farnesyl acetate,0.01 μ L eugenol,0.001 μ L linalool and 0.01 μ L methyl isonicotinate showed significant attractive activities to M.usitatus.When mixed the aggeration pheromone with eugenoland linalool,respectively,there was antagonistic effect,the mixture showed no attractive activities to M.usitatus.when mixed the aggeration pheromone with methyl isonicotinate,the mixture showed attractive activities to M.usitatus,but did not have synergistic effect compared with single compound.4.The effects of aggregation pheromone and plant volatiles mixtures on the behavior of F.intonsa: 1000 ng F.intonsa aggragation pheromone compound neryl(S)-2-methylbutanoate,0.1 μL linalooland,0.1 μL methyl isonicotinateshowed significant attractive activities to F.intonsa.When mixed the aggeration pheromone with linalool andmethyl isonicotinate,respectively,there were antagonistic effects,the mixtures showed no attractive activities to F.intonsa.By contrast,when mixed the aggeration pheromone with methyl isonicotinate,the mixture showed attractive activities to F.intonsa,but did not have synergistic effect compared with single compound.In conculsion,only 500 ng T.palmi aggregation pheromone mixed with 0.01μL linalool havea synergistic effect on the attraction of thrips aggregation pheromone.The rest combinations hadno influence or antagonistic effect on the thrips aggregation pheromone.Our results provide instructions for proper usage of thrips attractants based on aggregation pheromone and plant volatiles,and form the basis for the development of more efficient thrips attractants.