In this chapter, the adverse effects of transgenic cotton on nontarget flower visitors (such as honey bees and Bombus spp.) in Vietnam are discussed, focusing on the following: (i) potential reduction in pollination value; (ii) potential reduction in the economic value of bee products; (iii) potential adverse effects stemming from reduction in wild bee populations, including effects on other species and loss of genetic diversity; and (iv) potential reduction in species with conservation value or biological control value. The following procedures for the assessment of the potential effects of Bt cotton on non-target flower visitors in cotton ecosystems in Vietnam are discussed: (i) list non-target flower visitors and identify species for further evaluation; (ii) identify potential exposure pathways and potential adverse effect pathways; (iii) formulate risk hypotheses based on the identified exposure pathways and adverse effect pathways; (iv) and design experiments testing the risk hypotheses. Some possible experimental designs are presented, and the analysis and interpretation of field biodiversity studies are discussed.
Phenacoccus solenopsis Tinsley,a new invasive species in China,is a worldwide pest causing serious threat to the production of agriculture and forestry. Morphological identification of this mealybug species is limited by high degree of similarity and polymorphism. In the present study,a method was described for the development of DNA markers for rapidly identifying P. solenopsis. A pair of universal primers was designed based on published mitochondrial DNA cytochrome c oxidase subunit Ⅰ (mtDNA COI) gene sequences of mealybugs in GenBank. The mtDNA COI genes from P. solenopsis and seven other mealybug species common in China including Pseudococcus comstocki Kuwana,Planococcus lilacius Cockerell, Maconellicoccus hirsutus ( Green ), Saccharicoccus sacchari ( Cockerell ), Dysmicoccus neobrevipes Beardsley ,Planococcus minor Maskel and Phenacoccus solani Ferris were amplified and sequenced. And then one pair of species-specific COI ( SS-COI) primers was designed. The SS-COI primers amplified a single band of 546 bp from P. solenopsis. The specificity of the primer pair was validated using the seven other mealybug species mentioned above. The results showed that all and only P. solenopsis specimens were detected,and no cross reactions with other mealybugs were observed. The method was tested with individuals of the egg , 1st,2nd and 3rd instar nymph and female adult,and demonstrated to be applicable for all life stages. Furthermore,the primer set was tested with one P.solenopsis population from Pakistan and fourteen P. solenopsis populations from invaded areas in China and proved to be applicable for all geographic populations. The diagnostic PCR assay developed here provides a quick,simple and reliable molecular technique for the identification and monitoring of P. solenopsis , which will be useful in intercepting and blocking the further spreading of P. solenopsis.
【Objective】 The experiment was conducted to investigate the inter-specific competitive interaction between Ageratina adenophora (Sprengel) and Setaria sphacelata (Schum) at different densities, and to explore the methods of controlling the invasive weed A. adenophora displaced by S. sphacelata.【Method】 The above two perennial species were grown for 2 years in monoculture and mixture on an experimental densities gradient. The above-and blow-ground biomass of the two species were measured and the growth response and relative competitive ability were evaluated.【Result】 The total biomass, relative yield and competitive balance index of S. sphacelata were significantly higher than those of A. adenophora, the relative yield total was significantly lower than 1. The relationships mentioned above become more obvious with decreasing of experimental plant community densities. The total biomass of A. adenophora at the densities of 20, 45 and 175 plants/m2 in mixture decreased by 33.0%, 38.5% and 70.1% compared to those in monoculture, respectively. However, the total biomass of S. sphacelata at the same density between monoculture and mixture showed no significant difference. The ratios of root mass vs shoot mass of S. sphacelata in mixture were significantly lower than those in monoculture. However, the ratios of root mass vs shoot mass of A. adenophora in the mixture were significantly higher than those in monoculture【.Conclusion】There was a significant mutual antagonism between A. adenophora and S. sphacelata compared to A. adenophora, the relative competitive ability of S. sphacelata was higher, which decreased heavily the growth of A. adenophora mainly by shoot competition. It will be a promising strategy for replacement control of A. adenophora by using S. sphacelata as a competitor.
In tobacco fields of Shandong Province, population of the green peach aphid, Myzus persicae (Sulzer) reached its peak in late May to early June, and population of the oriental tobacco budworm, Helicoverpa assulta (Guenee), occurred from middle to late June. Predacious natural enemies included ladybirds, lacewings, predacious bugs, rove beetle and spiders, but populations were low and lagged behind the population peaks of insect pests. Aphidius gifuensis Ashmead, Campoletis chlorideae Uchida and Ovomermis sinensis Chen were the dominant parasitoids. Population of A. gifuensis correlated significantly with that of the green peach aphid and the ratio of A. gifuensis to aphid during the early season reached or approached 1. Parasitism of C. chlorideae against 1-3 instar larvae of the oriental tobacco budworm in June and July was 74 0% and 49.8% respectively. O. sinensis only occurred in middle July, and parasitism against larvae of the oriental tobacco budworm older than 3rd instar reached 35 2%.
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