Life tables for experimental populations of Frankliniella occidentalis on 6 vegetable host plants

Western flower thrips,Frankliniella occidentalis(Pergande),has become one of the most important agricultural pests worldwide,because of its extensive host range,reproductive capacity,invasion potential,plant viruses transmition ability and insecticide resistance.All of these interrelating factors are related to the basic life cycle and life history of the species,making western flower thrips the significant,difficult pest to manage.More than 500 kinds of host plants of western flower thrips have been reported.Notably,more and more serious damage to vegetables by F.occidentalis has been observed in recent years and the levels of damages were different with vegetable species.In order to know the differences and offer basis data for control,the life tables for experimental populations of F.occidentalis were established at constant temperature of 25 ℃,relative humidity of 70% and photoperiod of 16L∶ 8D,on cucumber,lettuce,eggplant,cabbage,celery and garlic leaves,respectively.The results showed that the thrip could develop and reproduce on all tested host plants,and there were significantly differences in the developmental periods,survival rates and fecundities on the 6 vegetable hosts.The shortest time for F.occidentalis to complete one generation was 11.43 days on cucumber,and the longest was 16.11 days on celery.The survival rates of F.occidentalis at different stages were different on different host plants.In short,the highest generation survival rates were on eggplant and garlic,and the lowest were on celery and cucumber.The fecundities per female per day were 2.88 on cabbage and 2.48 on lettuce,which were much bigger than those on other hosts,and the least was 0.77 on garlic.From all the life history of F.occidentalis,the number of female offsping increased at beginning and then declined,with the obvious oviposition peaks varying with different hosts as time increased.The rates of F.occidentalis female offspring on cabbage 1.9694 and lettuce 1.7649 per female per day were significantly higher than on other host plants.In addition,the sex ratio of offspring was also the highest on the two hosts,0.72 and 0.76,respectively.The innate capacity of increase(rm) of experimental population of F.occidentalis on cucumber,lettuce,eggplant,cabbage,celery and garlic was 0.1318,0.1228,0.1154,0.1197,0.0860 and 0.0791,respectively,and the net reproductive rate(R0) was 19.1248,30.8523,17.9322,34.5322,8.9491 and 8.3536,respectively.There were no significant differences in the mean generation time(T),and the trend indexes of experimental population(I) of F.occidentalis were similar to R0.Based on the parameters of the life tables on different hosts,the most suitable host plants for the development and reproduction of F.occidentalis were cabbage and lettuce,followed by cucumber and eggplant,the least celery and garlic.It could be concluded that host was an important factor influencing the development and fecundity of F.occidentalis populations.A lot of studies pointed out that there were many factors influencing the feeding,growth,development and oviposition of insects,such as flower,nutritional status,secondary substances and so on.So much more work needed to do for further understanding the differences and mechanism of F.occidentalis on different hosts.