| Agromyzid leafminer is one of the most important small pests in the world damaging vegetables,flowers and other economic crops.China is one of the countries with most serious diseases in the world.The rapid invasion of Liriomyza sativae intensified the dangerous situation,leading to serious economic losses,so it is the prior method currently to use rationally the parasitic wasps for "green" control.Neochrysocharis formosa(Westwood)(Hymenoptera: Eulophidae)is an advantage and important parasitic natural enemy of the leaf miner.The parasitic wasp has not only the host feeding behavior of parasitic host larvae,but also has a strong non-reproductive host killing behavior: host feeding and host stinging of the non-reproductive host killing behavior,which significantly increased control potential.In May-June 2015,we found that there were parthenogenetic females in the flies of the leafhopper,which were collected from Beijing,and then found that there were coexistence with both sexes in Hainan and other provinces,and they are all advantageous Neochrysocharis formosa.As the thelytokous characteristics of parasitic wasps have high biocontrol value,it is necessary to study the basic characteristics of biology and ecology of parasitic wasps.We established a stable population in the room and firstly tested its molecular identification,and then at room temperature through the comparison of the two sexes we comprehensively evaluated the control potential from the life history and life table.Because we are not clear about the fact that the main environmental factors-temperature adaptation range of nature,we studied the adaptability of temperature from the two levels of immature and mature life history characteristics,and compared the biological characteristics of the basic characteristics of the two strains.The key research findings are as follows:1.Molecular identification of the thelytokous strain of Neochrysocharis formosa (Hymenoptera: Eulophidae)newly found in China and detection of its endosymbiont RickettsiaIn June 2015,we first discovered the thelytokous strain of N.formosa in Beijing.In order to provide theoretical reference for synchronously releasing the thelytokous strain and arrhenokous strain as bio-control agents in the field,these two strains of N.formosa were indentified at the molecular level,which are difficult to recognized in morphology.First,the special primers Nfor Rick1/Nfor Rick2 of Rickettsia were used to amplify the 16 S r DNA of the thelytoky and arrhenotoky of N.formosa raised indoor.Second,we analysed the genetic distance between thelytokous and arrhenotokous strains of N.formosa using multiple molecular markers(COI,ITS1,28 Sr DNA).The target gene fragment of Rickettsia in the Chinese thelytokous strain is consistent with Japanese sequence(ac.no.AB185963).Constructing phylogenetic trees thoughexploiting two COⅠ gene fragments as molecular markers,which were amplified by the primer LCO1490/HCO2198 and COⅠ1/COⅠ2.,the two strains of N.formosa fell into two distinct clades andthe genetic distance is 0.039 and 0.023,respectively.Using the ITS-1 gene and 28 S r DNA as molecular markers,there are 21 and 0 sites discrepancy,respectively and the genetic distance with ITS-1 gene is 0.008.The arrhenotokous and thelytokous strains of N.formosa can not be separated by 28 S r DNA,however,both ITS-1 and COⅠ can effectively identify the two strains.2.The evaluation of control potential of the two strains from life history and life tableAre the potentials of the two strains differentiating? We compared the two strains of Neochrysocharis formosa from life history parameter value,so as to provide a theoretical guidance for the field release of the two strains.We fed two strains of Neochrysocharis formosa(26 ℃)and constucted twosex life table.The results showed that there was no significant difference in egg duration,pupal duration,and immature duration.There were no significant differences in the longevity and fecundity of the two strains,but the number of hosts,the number of directly killed hosts and the total number of deadly hosts were significantly higher than those of the the arrhenotokous strain.The results showed that two strains were highly synovigenic,and the oviparous index was 0.011 and 0.014.host-feeding was beneficial to the occurrence and maturation of the eggs,parasitic wasp feed 1/per to contribute fecundity and longevity and those of the two strains were 0.2 and 0.3 respectively,and the contribution to life was 0.06 d,no significant difference with them;1.Molecular identification of the thelytokous strain of Neochrysocharis formosa The thelytokous strain of life expectancy,age-specific fecundity and the age-characteristic reproductive value results showed that the life expectancy of was higher than that of the arrhenotokous strain;The age-stage survival curve showed that there was no significant difference in the survival rate between the two strains at the immature stage The results showed that intrinsic increase rate,finite increase rate and net reproductive rate were significantly higher than those of the arrhenotokous strain.Consolidated results showed that the thelytokous strain had greater potential for control than the arrhenotokous strain.3.Effects of temperature on the parameters of immature life table of two strainsThe two strains coexist in the field,the response of immature development on the important environmental factors-temperature is different? We set up five different temperatures(18 ℃,22 ℃,26 ℃,30 ℃ and 34 ℃)to study the different temperatures on the impact of the two strains of immature life history parameters.Under the five temperature conditions,every immature period showed a shortening with the temperature increasing;The body length increased first and then decreased,the thelytokous strains of N.formosa and the male of the arrhenotokous strain was the highest peak at 26 ℃,while the female of the arrhenotokous strain reached the highest peak at 30 ℃;Oogenesis increased first and then decreased with the temperature increasing,The number of mature oocyte in both strains reached the maximum at 26 ℃.Under the same temperature conditions: 18 ℃,22 ℃,26 ℃ and 30 ℃ mainly showed that the developmental duration of the female of the arrhenotokous strain were significantly longer than that of the thelytokous strains and the male of the arrhenotokous strain.However,at 34 ℃,the thelytokous strains were significantly longer than those of the arrhenotokous strain;The length of the female of arrhenotokous strain was longer than that of the thelytokous strain and the male of arrhenotokous strain,there was no significant difference between the thelytokous strain and the male of arrhenotokous strain at 18 ℃,26 ℃and 30℃.At 22 ℃ and 34 ℃,the length of he thelytokous strain was significantly longer than that of the the male of arrhenotokous strain.There was no significant differences in the number of mature oocyte of two strains.The comprehensive analysis showed that the two strains had a certain degree of differentiation in the immature period.4.Effects of Temperature on Life History and Control Potential of the thelytokous strains of N.formosaIn order to meet the temperature range of the thelytokous strains of N.formosa,we set up four temperature treatment groups(22 ℃,26 ℃,30 ℃ and 34 ℃).The results showed that the longevity of the female in the host treatment group and the water treatment group was shortened with the increase of temperature,and both 22 ℃ and 26 ℃ longer than 30 ℃ and 34 ℃ observably.With the increase of temperature,the number of host-killing was increased first and then decreased,and the number of host-killing reached the highest at 30 ℃.Daily host mortality events and total number of deadly hosts at 30 ℃ were significantly higher than those at other temperatures.Daily host-feeding events were significantly lower than those at other temperatures;The number of longevity,parasitoids and host-stinging were significantly correlated with the number of host-feeding.The number of parasitoids and host-stinging were significantly positively correlated with longevity.The results also further illustrate adult female of the thelytokous strain can adapt the high temperature.In summary,the thelytokous strains of N.formosa is the dominant parasitoid wasp,the characteristics of the thelytoky relative to the arrhenotokous strain is doubled,is also the host-feeding parasitic wasp.Non-reproductive host mortality ratio(up to 86% at 26 ℃)is higher,adapting to temperature range is wider(the strongest control effect at 30 ℃)relatively.The systematic study of this paper can provide theoretical guidance for its application practice(such as large-scale breeding,field release,joint control,ecological regulation,etc.)as a natural enemy. |
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