The cellulase activities of workers (or pseudoergate) of five species of common termites, Reticulitermes flaviceps, R. leptomandibularis, Coptotermes formosanus, Odontotermes formosanus, and Cryptotermes pingyangensis, were studied in China. The results indicated that R. leptomandibularis workers had the highest activity of b-glucosidase and cellulase against carboxymethyl cellulose (CMC), Cry. pingyangensis pseudoergate had the highest activity of cellulase against CMC and O. formosanus had the largest b-glucosidase activity in the head compared to other tested termites. R. leptomandibularis in the foregut and hindgut and C. formosanus in the midgut had the highest activity of cellulase against CMC, and R. flaviceps in the hindgut and C. formosanus in the midgut had the largest b-glucosidase activity among the five tested termites. The main digestive sites of CMC and salicin for Cry. pingyangensis were in the foregut and midgut. The strongest digestibility of CMC was in the foregut for R. flaviceps and R. leptomandibularis and in the foregut and midgut for C. formosanus. The digestion of salicin for O. formosanus and C. formosanus were concentrated in the head and midgut, respectively. R. leptomandibularis and R. flaviceps had the strongest digestibility of salicin in the head and hindgut.
The purification of the cellulase from Odontotermes formosanus workers was achieved by using anion‐exchange column of UNOsphere Q, BioLogic DuoFlow chromatography system. The purified cellulase was identified as an endoglucanase and some of its properties were investigated. The EGase activity was 807.5‐fold as high as the initial enzyme activity using CMC as substrate and 14.4‐fold using salicin as substrate. The enzyme preparations were homogeneous as judged by SDS‐PAGE electrophoresis, molecular weight of which was 80 kDa and confirmed by 2‐DE zymogram analysis. The enzyme was isoelectric at pH 6.4, which was active on CMC substrate.
Acetamiprid is a novel neonicotinoid insecticide invented by Nippon Soda Co., Ltd. . To explore the possibility of acetamiprid as larvicide of mosquitoes, lethal and sublethal effects of acetamiprid on the larvae of Culex pipiens pallens were studied by immersion method in the laboratory. The results indicated that the larvae of Culex pipiens pallens were sensitive to acetamiprid. The mortality of larvae peaked at 72 h after treatment. The 1 st instar larvae was the most susceptible to acetamiprid, and the 4th instar larvae was the most tolerant to acetamiprid, the LC,, values were 0.020 mg/L and 0.296 mg/L at 72 h after treatment, respectively. Sublethal concentrations of acetamiprid could delay the development of larvae and decrease the weight of pupa. We suggested that acetarniprid is a safe and effective substitute for the using larvicides of mosquitoes.
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