Pathway Of CrylAb Protein In The Food Chain From Bt Irces Through Nilaparvata Lugens To Cyrtorhinus Lividipennis

One of the main debates of the use of Bt transgenic rice was regarding that whether theBt toxin could be ingested by nontarget insects with piercing-sucking mouthparts.Cyrtorrhinus lividipennis Reuter is one of the main predators of Nilaparvata lugens in paddyfield. Although the previous experiments have shown that CrylAb protein in Bt transgenic rice“KMD1” and“KMD2”could be transfered through N. lugens to C. lividipennis, howeverits pathway and channel were still unkown so far. In order to find the potential CrylAb proteintransfered pathway, the objects of this study on the non-target food chain in paddy fields: Btrices to N. lugens to C. lividipennis were focused. Results are as follows:1)The eggs of N. lugens: By scanning on the egg shell structures of N. lugens underelectronic microscope, it showed that most of the egg shell surface was smooth except forsome pores arranged neatly around the egg cap. Through immunofluorescence on the eggshells surface and Frozen section fluorescent positioning in egg contents of N. Lugens that fedon Bt rice seedlings, results showed that CrylAb protein could be found from the egg shelland its content both. While the eggs of N. lugens that fed on non-transgenic rice seedlings, noCrylAb protein could be found from its eggs. From the detection on equal amount of6-day-old egg, egg shells and newly hatched nymphae of N. lugens fed on Bt rice seedlings,results showed that CrylAb protein could be detected mainly from the egg shells. While N.lugens was fed on Bt rice seedlings, CrylAb protein could be detected from N. lugens eggswith different daily variation stages, but could not be accumulated according to the egg’sstages varied.2) Rice seedling and its guttation: After detecting the rice seedling guttation collectedfrom both Bt transgenic and non-transgenic rice seedlings, the results showed that CrylAbprotein could easily be detected in the guttation from Bt rice seedlings, rather than that fromnon-transgenic rice seedlings. When the predator, C. lividipennis, was fed on Bt rice seedlingsthat dyed with methylene blue, its nymphal midguts could also be dyed. Meanwhile, when only Bt rice seedling was provided, CrylAb protein could only be detected from the nymphaeof C. lividipennis, and was unable to be found from its adults. It indicated that nymphae of C.lividipennis could directly suck the rice seedling and its guttation, as well as ingested itsCrylAb protein.3) The honeydew of N. lugens: After feeding on Bt rice seedlings, the high concentrationof CrylAb protein could be detected from the honeydew of N. lugens. When Bt rice and N.lugens were provided simultaneously, the nymphae and adults of C. lividipennis could feed onthe honeydew of N. lugens fed on Bt rice. However, if the predator of C. lividipennis was fedon the honeydew of N. lugens alone, CrylAb protein was unable to be found both from itsnymphae and adults.4) Copplex pathways: From the detection of ELISA, the results showed that CrylAbprotein could be found in the adults, newly hatched and4th instar nymphae of C. lividipennisfed on the Bt-rice and N. lugens. The content of CrylAb protein in newly hatched nymph wassignificantly higher than other nymphal and adult stages and decreased gradually according totheir developing stages varied. However, the contents of CrylAb protein in eaqual amount ofN. lugens’ eggs preyed by C. lividipennis was under the limit line and too few to be detected.So, the transfered pathway of CrylAb protein by C. lividipennis should be complex pathways.Consequently, under the laboratory conditions in this study, the pathway of CrylAbprotein ingested by C. lividipennis should be through complex pathways: directly derivedfrom Bt rices, prey and its honeydew. The feeding habits of C. lividipennis could varied indifferent developing stages, especially its nymphal feeding habits were facultative feeding onrice.