| Agromyzid leafminer is a kind of important small pests of vegetables, flowers and other economic crops in the world. In China, especially the four leafminers invasion, Liriomyza sativae(Blanchard), L. huidobrensis(Blanchard), L. trifolii(Burgess) and L. bryoniae(Kaltenbach) caused serious damage to vegetables and other crops. Due to the numberous use of pesticides, leafminer resistant was increasingly servious, threatening human health and ecological safety. Therefore, biological control using natural occurring enemies, such as parasitoids or predators, of leafminer pests had attracted many attentions of entomologists and ecologists and become a pupular research topic.In this paper, two predominant leafminer parasitoids, Diglyphus isaea and Neochrysocharis formosa were taken tocompare the life history traits and its physiological mechanisms. The main results and conclusions were showed below:1. Comparision of the pre-adult developmental period and initial egg load of two parasitoids.We observed the developmental period of two parasitoids, such as egg-larval stage, pupal stage, and dissected their initial egg loads. For D.isaea,the developmental time of egg–larva stage and pupal stage were 5.24±0.07 and 4.47±0.09 days, respectively, whilethey were respective 5.47±0.05 and 6.83±0.09 days for N. formosa. However, there was no significant difference of egg-larval stage between them, but significant difference was showed on pupal stage. Of a newly emerged D.isaea, the number of immature eggs(class I and II) and mature eggs(class III) were 3.00 ± 0.22 eggs, 0.79 ± 0.25 eggs and 0.13 ± 0.07 eggs, respectively; for N. Formosa, they were 4.78 ± 0.42 eggs, 1.85 ± 0.32 eggs and 4.08 ± 0.35 eggs.That means both D.isaea of N. formosa are synovigenic parasitoid.2. Additional non-host food affect the life history of D. isaea and N. formosa.During this part, we compared the effects of non-host food(10% glucose) on the life history traits of two parasitoids, such as longevity, fecundity, host-feeding event, host stinging and so on. Furthermore, we analyzed the significance of non-host food on biocontrol efficiency of two parasitoids. The re s u l t s showed that: 1) additional non-host food(10% glucose) significant prolonged the longevities of two parasitoids, and then increased the total parasitoid-induced host mortality, host-feeding events, the number of host stinging, and total mortality, further significant improved the bio-control abilities; 2) For D.isaea, additional non-host food can improve the daily parasitoid-induced mortality but had no significant effect on daily host-feeding events, the daily host stinging, and daily total mortality; Similarly, additional non-host food had no significant effect on the daily parasitoid-induced mortality, the daily host-feeding events, the daily host stinging, and the daily total mortality; 3) There were significantly positive correlations between the host-feeding events and longevity, fecundity, host-stinging events and total host mortality of D.isaea in both treatments; meanwhile, there were significantly positive correlations between the number of host-feeding events and wasp longevity, fecundity, host-stinging events, total host mortality of N. formosa in the host treatment, while there were significantly positive correlations between the number of host-feeding events and wasp longevity, fecundity, total host mortality of N. formosa in the host+non-host treatment.3. Effects of host density on the host-killing behavior of D. isaea and N. formosaHost density is a key factor affecting the bio-control efficiency of parasitoid, so we conducted the effects of host density on the life history traits of two parasitoids. The results showed that :1) With the increaseing of host density, total mortality was increased for D.isaea, but it increased at the begining and then decreased for N. formosa; 2) as host density increasing, the number of host feeding events, fecundity, host-stinging events and host total mortality were increased, meanwhile, there were significantly positive correlations between host density and those traits of D.isaea and N.formosa; 3) for D.isaea, at low density(5 ~ 10), the parasitism, host-feeding event rate and host-stinging rate were respective up to 26.22%, 24.49% and 13.77%, and parasitization was the main behavior; at medium density(11~ 20), the parasitism, host-feeding event rate and host-stinging rate were 26.14%, 16.11%, and 32.9%, but host stinging and parasitization were the main behaviors; at high density(21~30), the parasitism, host-feeding event rate and host-stinging rate were 35.01%,11.94% and 40.23%, and host stinging was the key behavior. For N. formosa, at low density(5~ 10), the parasitism, host-feeding event rate and host-stinging rate were 23.81%, 32.72% and 7.1%, the parasitism and host feeding were the main behaviors; at medium density(11~ 20), the parasitism, host-feeding event rate and host-stinging rate were 29.22%,28.52% and 17.69%, mainly for the parasitization and host feeding; at high density(21~30), the parasitism, host-feeding event rate and host-stinging rate were 31.11%, 18.91% and 13.99%, mainly for the parasitization.4. Analysis of fatty acid composition and composition change of D.isaea and N. formosaWe evaluated the changeof the the fatty acid composition and the component proportion of triacylglycerol in different developmental stages of D.isaea and N.formosa. The effect of different food on fatty acid composition of D.isaea and N. formosa adults were also investigated.The results showed that: 1)The percentage of saturated fatty acids had no significant changes between larval stage and pupal stage of two parasitoids, significantly lower than female adults; the percentage of monunsaturated fatty acids had no significant change between larval and pupal stage, significantly higher than female adults; the proportion of polyunsaturated fatty acids had no significant changes between larval stage and pupal stage of D. isaea, significantly higher than in adult stage; the proportion polyunsaturated fatty acids in each developmental stage of N. formosa had no significant difference. 2) After the emergence, the proportion of saturated fatty acids, monunsaturated fatty acids and polyunsaturated fatty acids showed no significant difference for starvation, feeding 10% glucose or host larvae of D. isaea and N. formosa. |
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