Conjugation of δ‐endotoxin from Bacillus thuringiensis with abamectin of Streptomyces avermitilis as a new type of biocide, GCSC‐BtA, for control of agricultural insect pests

Abstract

Conjugation of d-endotoxin from Bacillus thuringiensis with abamectin, a toxin of Streptomyces avermitilis, was carried out to form a new type of biocide, GCSC-BtA based on ''Germany-China Scientific Cooperation'' research, for the control of agricultural insect pests. The strategy for biochemical linkage was designed by conjugating an amino group in B.t. protoxin with a carboxyl group in carboxylated abamectin under the treatment of conjugator EDC [1-Ethyl-3-(3-dimethylaminopropyl carbodiimide Hydrochloride)]. The formation of B.t. protoxin was processed by solubilizing B.t. crystal in 25 mM dithiothreitol (DTT) at 37°C for 2 h. The carboxylated abamectin was formed by carboxylating the NaH-activated abamectin with 10 mg/ml butyric anhydride at 111°C in a water-circumfluent condensation device for 2 h. The conjugating reaction, consisting of 5 mg/ml B.t. protoxin, 10 mg/ml carboxylated abamectin and 19.17 mg/ml EDC, was successfully conducted at room temperature for 24 h. Significant differences were found between pure abamectin, carboxylated abamectin and the conjugated BtA by means of UV-photo absorptions recorded at wavelengths 354, 438, 518, 600 nm (P < 0.01). LT 50 of the conjugated GCSC-BtA to the 3 rd instar larvae of Plutella xylostella (L.) (Lep., Plutellidae) was 35.27 lg a.i./ml, about 62 % and 76 % of that caused by the B.t. protoxin and the caxboxylated abamectin, respectively. The conjugated GCSC-BtA caused 87.14 % mortalities in larvae of P. xylostella, 93.75 % in adult Myzus persicae (Sulzer) (Hom., Aphididae) and 89.33 % in adult Phyllotreta vittata Fabricius (Col., Chrysomelidae) as compared to 48.33 % by the B.t. crystal only in P. xylostella. The symptoms caused by conjugated GCSC-BtA in the 3 rd instar of P. xylostella were black color in the head part and whiteyellow in the abdomen of dead larvae, which differed from the black color or the white-yellow all along the body caused by either the B.t. crystal or the abamectin, respectively. It was concluded that the conjugated GCSC-BtA biocide had a broader host spectrum and a faster killing speed than either the B.t. crystal or abamectin alone for the control of agricultural pests.B. Liu and C. Sengonca: Conjugation of Bacillus thuringiensis d-endotoxin with abamectin Anz. Schädlingskunde ⁄

Insecticidal activity and antifeedant effect of a new type biocide GCSC-BtA against Plutella xylostella L. (Lep., Plutellidae)

“…The present results are approximately comparable with the results of Liu and Sengonca (2003a) that the GCSC-BtA caused higher mortality of field-collected larvae of P. xylostella with 87.1% than 71.6 and 48.3% by B.t. crystal and Abamectin respectively, despite they did not evaluate the LC 50 .…”

“…; Martin and Hyde 2001;Chattopadhyay et al 2004), Abamectin (Wehner et al 1993) and GCSCBtA , of which the last one was a new type of biocide developed by conjugating deltaendotoxin of B.t. with Abamectin from Streptomyces avermitilis through conjugator EDC [1-Ethyl-3-(3-dimethylaminopropyl carbodiimide Hydrochloride)], used for controlling agricultural arthropod pests (Liu and Sengonca 2003a).…”

Toxicity of biocide GCSC-BtA on arthropod pests under different temperature conditions

“…Afterwards the leaves were kept in the climate chambers at the conditions mentioned above for further rearing till the desired stage in the next generation. The insecticides tested were the self-prepared biocide GCSC-BtA referred to the method provided by Liu and Sengonca (2003a, b), B.t. crystal (Bacillus thuringiensis var.…”

“…toxin with Abamectin from Streptomyces avermitilis through a conjugator EDC (Liu and Sengonca 2003a), had shown high toxicity against some vegetable pests like Tetranychus neocaledonicus Andre (Acari, Tetranychidae), Phytomyza nigricornis Macquart (Dip., Agromyzidae), Myzus persicae (Sulzer) (Hom., Aphididae), Phyllotreta vittata Fabric. (Col., Chrysomelidae) and Plutella xylostella L.…”

Impact of Tween 80 during Bacillus thuringiensis fermentation of wastewater sludges

“…Several surface active agents were screened in shake flask experiments to achieve higher entomotoxicity [11] and Tween 80 fortification of nonpretreated sludge medium was found to augment the Tx value by 24%. Other studies on semi-synthetic media have reported the use of Tween 80 as an additive to enhance substrate assimilation during Bt fermentation in shake flask experiments [12,13] and also in d-endotoxin purification and characterization studies [14]. There also has been extensive use of Tween 80 as wetting and suspending agent in formulations of biopesticides and also as spray mixes to improve spreading on foliage [15].…”