| Agromyzid leaf miner is one kind of worldwide importance small pest that harmful to the economic crops such as vegetables and flowers. China is one of the most severely countries affected by Agromyzid leaf miner. Especially the invasion and spread of Liriomyza sativae and Liriomyza trifolii (Burgess) exacerbated the hazard situation. It's very difficult to control the Liriomyza (such as L. sativae and L.trifolii), because of its wide distribution, hidden harm, rapid population proliferation,short development period, resistance to the pesticides and pesticide residues caused by food safety problems. The strategy of biological control based on parasitic wasps has been the main prevention and control strategy of leaf miner. Therefore, the evaluation and application of the parasitic wasps were the main means of controll the leaf miner.Hemiptarsenus varicornis (Girault) is the field advantage natural enemy (such as the dominant natural enemy of Hainan leaf miners) of vegetable leaf miner (such as L.sativae and L. trifolii). In present research, the L. trifolii larvae as the host, first at all,studied the life history and the control characteristics of the H. varicornis, and then further studied the effects of environmental impact factors on the control potential of adult nutrition, temperature and host density. And it also provides guidance for indoor mass-rearing techniques and application of this wasp in the field. The results were showed as follows:Life history and controlling pest characteristics: The life history and controlling potential of H. varicornis was studied systematically under the constant temperature of 27 ?. The results demonstrate that the immature developmental stages of male and female were 7.90 days and 7.52 days, respectively. The Life table parameter of that, the intrinsic rate of increase, the finite rate of increase, the net reproductive rate,the gross reproduction rate, and the mean length of a generation of H. varicornis were 0.3011/day, 1.3624/day, 66.22 offspring/individual, 168.33 offspring/individual, and 13.56 days, respectively. Host feeding significantly prolonged the life span of females. The parasitic wasps show three kind of host-killing behaviors: parasitism, host-feeding and host-stinging (non parasitism and host-feeding), and they were 133.91hosts, 303.75 hosts and 84.16 hosts, respectively.Effects of adult nutrition on the controlling pest potential: We compared the effects of different treatments: water starvation (control), 20% glucose, 20% honey,host larva, host larva-plus-20% glucose and host larva-plus-20% honey, the female life history parameters of adult under the constant temperature of 27 ?. The results showed that, compared with the control, 20% glucose and 20% honey treatment can significantly prolong the life of male and female, but the difference between the two is not significant. The life,fecundity,host-feeding events,host-stinging events and total host mortality of the female was not significantly enhanced when fed on host larva-plus-20% glucose and host larva-plus-20% honey than fed on host larva, but significantly reduced the average daily host-feeding events of female. In the "feeding vs parasitism" behavior trade-offs also significantly reduced the proportion of total host mortality and parasitism of host-feeding events.Effects of temperature on the controlling pest potential of females: The life history parameters of female adults were studied at 22?, 26?, 30? 34? treatment.The results showed that, the life span of the males and females decreased with the increasing of temperature, but it was not significantly difference at 22 ? and 26 ?.The parasitism, host-feeding events, host-stinging events and total host mortality of H.varicornis at 26? and 30? were significantly higher than 34?. The daily average parasitism and daily average total host mortality of females at 26 ? and 30? were significantly larger than 22 ? and 34 ?. The daily average host-stinging events were the highest at 26? (5.04) and the daily average host-feeding events were the highest at 34? (19.51). In the "feeding vs parasitism" behavior trade-offs, the females significantly tend to parasitism at 22 ? --30?, and significantly tend to host-feeding at 34 ?.Dependence of females control behavior on host density: We compared the life history parameters of four-day-old females were measured at 10, 20, 30, 40, 50 and 60 host density for nine hours, under the constant temperature of 26? .The results showed that, the host-feeding events, host-stinging events and total host mortality of H. varicornis were increased with the increase of density of host, but the parasitism events was not increaseed significantly at 30 to 60 host density. The relationship between the parasitism (Np), host-feeding events (Nf), host-stinging events (Ns) and total host mortality (Nm) and the host density (N) show the positive acceleration curve.The mathematical model of density functional response conforms to Holling II type disc equation,they were Np=3.236x0.375N/ (1+3.236×0.031N),Nf=1.111x0.375N/(1+1.1 11×0.010×N),Nm=3.166x0.375N/(1+3.166x0.008N),but except for host-stinging events (Ns). In the "feeding vs parasitism" behavior trade-offs, the females significantly tend to parasitism at 10 to 30 host densities, and significantly tend to host-feeding at 40 to 60 host densities.H. varicornis has three host killing behaviors. Especially the non-reproductive host behavior significantly increased the controlling pest potential of females. Adult supplementation of non-host food nutrition did not significantly enhance the potential of controlling.Parasitic weasps adapt to a wide range of temperature,high temperature resistant, the strongest controlling pest potential at 26?. The control behavior of females has host density dependence and the greatest controlling pest potential in high density. The above results provide guidance for the indoor large-scale rearing and field release of Agromyzid leafminer's natural enemies. |
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