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

Abstract

The present research dealt with the toxicity of GCSC-BtA (Germany-China Scientific CooperationBacillus thuringiensis-Abamectin), a new type biocide developed by conjugating a toxin from Bacillus thuringiensis (B.t.) with Abamectin from Streptomyces avermitilis, on arthropod pests under different temperature conditions. The results showed that GCSC-BtA possessed higher toxicity than B.t. crystal, Abamectin or Cypermethrin, with pest mortalities of 97.9, 93.7, 96.4, 82.3 and 96.7% for Tetranychus cinnabarinus (Boisd.) (Acari, Tetranychidae), Frankliniella occidentalis Pergande (Thys., Thripidae), Aphis fabae Scopoli (Hom., Aphididae), Plutella xylostella (L.) (Lep., Plutellidae) and Cameraria ohridella Deschka et Dimic´(Lep., Gracillariidae), respectively. Toxicities of GCSC-BtA to T. cinnabarinus and P. xylostella decreased significantly at the older developmental stage with an exception that egg stage had the highest tolerance, in which LC 50 s of GCSC-BtA were 0.0001, 0.0019 and 0.0708 mg/ml for nymph, adult and egg of T. cinnabarinus, and that 0.0399, 0.2035 and 0.9033 mg/ml for the 2nd instar larvae, 4th instar larvae and egg of P. xylostella, respectively. Also, the biocide was more effective to the lower stage of A. fabae than the higher one with LC 50 s of 0.0023, 0.0086 and 0.0171 mg/ml against 1st instar nymph, 3rd instar nymph and adult, respectively. In general, toxicity of the new type of biocide was positively related to temperature against all the tested pests, except against T. cinnabarinus, where it was almost similar at the three temperature conditions. GCSC-BtA displayed significantly lower toxicities at 15/20°C than 20/25°C or 25/30°C against F. occidentalis, A. fabae, P. xylostella and C. ohridella. However, no significant difference was found in the toxicities against F. occidentalis, A. fabae and C. ohridella above 20°C, whereas toxicity against P. xylostella increased as temperature raised. Therefore, to achieve higher efficacy in the field, application rate and time should be devised according to these factors.

Thermal plasticity and sensitivity to insecticides in populations of an invasive beetle: Cyfluthrin increases vulnerability to extreme temperature

“…Yet, these authors used constant temperatures in their experiments. The increased negative effects of the insecticide for adult A. diaperinus experiencing a daily heat spike of 6 hours is consistent with the findings of several other studies (Delnat et al 2019;Willming, Qin, and Maul 2013;Zhu, Sengonca, and Liu 2006), who found increasing pesticide toxicity in insects subjected to daily bouts of high J o u r n a l P r e -p r o o f temperatures. For instance, daily thermal fluctuations as low as 5 °C increased toxicity of chlorpyrifos in damselfly larvae .…”

Isolation and characterization of an abamectin-degrading Burkholderia cepacia-like GB-01 strain

“…Abamectin shows effects on reproduction, biological function and survival of non-target terrestrial organisms that have important roles in the food web (Strong 1992;Shipp et al 2000;Zhu et al 2006;Jensen et al 2007;Diao et al 2007;Kolar et al 2008). Moreover, abamectin can runoff from the sites of application, so the possibility exist that agricultural use of pesticide or administration to animals could result in its indirect introduction to nearby water bodies, leading to the exposure of aquatic organisms.…”