We analyzed molecular and enzymatic properties of three cholinesterases (ChEs; ClAChE1, ClAChE2 and ClSChE) from Cimex lectularius. The ClAChE1 and ClAChE2 were generally present as a membrane-anchored dimeric insoluble form in the brain and ganglia. In the case of ClSChE, monomeric and dimeric soluble forms were observed. To investigate enzymatic properties, three ChEs were functionally expressed using baculovirus expression system. ClAChE1 revealed a significantly higher activity than ClAChE2 to acetylthiocholine iodide (ATChI) substrate. Kinetic analysis using two choline substrates (ATChI and butyrylthiocholine iodide) demonstrated that ClAChE2 had higher catalytic efficiency but lower substrate specificity than ClAChE1. Inhibition assay was conducted by using three inhibitors (BW284C51, eserine, Iso-OMPA) and two insecticides (chlorpyrifos-methyl and carbaryl). Two ClAChEs revealed high sensitivities to BW284C51, eserine, chlorpyrifos-methyl and carbaryl, but were not sensitive to Iso-OMPA. This inhibition profile confirmed that both ClAChEs are categorized as ChEs. Interestingly, the salivary specific cholinesterase did not show any measurable activities to choline substrates, confirming its non-synaptic function in C. lectularius

The impact of transgenic Bt maize plant contained Cry1F was evaluated on the oat aphid Rhopalosiphum padi as a non-target insect species. Slightly reduced rates of survival and alata vivipar production were observed on Bt maize than on the non-Bt maize. In addition, slightly low preference to Bt maize plant was observed. Aphid fecundity, measured as the number of offspring produced for 7 days, was higher on Bt maize than on non-Bt maize but not different significantly. ELISA test using Cry1F-antibody revealed that 26% of Cry1F protein compared to the positive control was detected from the whole body of R. padi when the insects were fed Bt maize for 50 days, showing that R. padi can carry Cry1F protein to the higher trophic level when exposed to Bt maize. Taken together, the Bt maize plant is not likely to cause any negative side impacts on non-target insect R. padi but Bt toxin can be transferred to higher predators via R. padi as it carries the toxin.