| Both Liriomyza sativae Blanchard and Liriomyza trifolii (Burgess) are insect pests ofvegetable crops, ornamental plants and commercial crops throughout the word. Due to owning thecharacteristics of wide host range, fast spread, resistance to pesticides, high fertility and easybreakout, they are very difficult to control. The two species performed fierce interspecificcompetition and displacement from1970s around the world. L. trifolii have gradually become thepredominant species since it was found in2006in Hainan Island. We mainly examined theimpacts of temperature, host plants and tracking surveys of their population dynamics to study thepossible mechanisms of their competition and population replacement. We expected to providetheoretical basis and technical support for competition and replacement of different populationsand effective strategies for the management of leafminer fly. The main results as follows:We summarized the choice for different host plants of the two species, the factors of thedifferent choices and the influences of temperature and host plant on interspecific competition anddisplacement between insect species. We also analysed research progress on the interspecificcompetition between the two species at home and abroad.Influences of temperature on interspecific competition between L. sativae and L. trifolii weredetermined. There was no L.sativae adults while the number of L.trifolii in F1progeny was(3.5±1.0) in14℃. The number ofL.sativae adults (8.8±1.7) was more than that ofL.trifolii(4.5±1.1) in F1progeny in21℃.There was no significant difference between L.sativae(8.4±1.9) and L.trifolii (9.2±2.4) in F1progeny in28℃.The number ofL.trifolii adults (1.5±0.4)was more than that of L.sativae (0.8±0.2) in F1progeny in35℃.The choice of L.sativae and L.trifolii adult female to odours of pea bean leaves, towel gourdand kidney bean leaves and repellent function to the other species of ovipositing leaves and larvalleaves were determined. We found that the choice order from high to low of L.sativae femaleadults to different leaves was pea bean>towel gourd> kidney bean, the order of L.trifolii femaleadults was kidney bean> pea bean> towel gourd. The repellent function of L.sativaeovipositing leaves and larval leaves to L.trifolii adult female was not significant, but the repellentfunction of L.trifolii ovipositing leaves and larval leaves to L.sativae adult female was verysignificant.Selectivity and adaptability of L.sativae and L.trifolii to3different host plants were analysed.The results showed that both species owned the fastest development rate in pea bean, the pupationrate of L.trifolii in towel gourd was very low. The number of L.trifolii feeding in towel gourd wasless than that of other hosts while the number of oviposition was many. The number of feedingand oviposition of L.trifolii was more than that of L.sativae in pea bean and kidney bean. Therewas no correlation between the number of feeding, oviposition per unit area and the soluble sugars,soluble protein and laminas chlorophyll.The two species stared with different proportion of competition in different host plants. The results showed that the competitive advantage of L.trifolii was significant when the number ofL.trifolii population was more than that of L.sativae in pea bean and kidney bean. The competitiveadvantage of L.sativae was outstanding when the competition started with any proportion in towelgourd. The more fierce competition mix population went through the less number of F1progenywas.We conducted the surveys of the occurrences of the leafminers in Tangshan, Hebei Provinceand tracking surveys of the population dynamics of the two species across Hainan Island,especially in Sanya. The range of the host plants of L. trifolii was broader than that of L. sativae.The population proportion of L. trifolii has been increased by years. L. trifolii has become thepredominant species in some locations and it maybe displace L. sativae population. |
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