cyhalothrin and fluphenacur

The exploration of new niches for microorganisms capable of degrading recalcitrant molecules is still required. We hypothesized the gut microbiota associated with insect-resistant lines carry pesticide degrading bacteria, and predicted they carry bacteria selected to degrade pesticides they were resistant to. We isolated and accessed the pesticide-degrading capacity of gut bacteria from the gut of fifth instars of Spodoptera frugiperda strains resistant to lambda-cyhalothrin, deltamethrin, chlorpyrifos ethyl, spinosad and lufenuron, using insecticide-selective media. Sixteen isolates belonging to 10 phylotypes were obtained, from which four were also associated with the susceptible strain. However, growth of gut bacteria associated with larvae from the susceptible strain was not obtained in any of the insecticide-based selective media tested. Growth of isolates was affected by the concentration of insecticides in the media, and all grew well up to 40 μg/ml. The insecticide-degrading capacity of selected isolates was assessed by GC or LC-MS/MS analyses. In conclusion, resistant strains of S. frugiperda are an excellent reservoir of insecticide-degrading bacteria with bioremediation potential. Moreover, gut-associated bacteria are subjected to the selection pressure imposed by insecticides on their hosts and may influence the metabolization of pesticides in insects.

Topics: Animals; Bacteria; Benzamides; Biotechnology; Drug Combinations; Gas Chromatography-Mass Spectrometry; Gastrointestinal Microbiome; Insecticides; Macrolides; Nitriles; Pyrethrins; Spodoptera; Tandem Mass Spectrometry

Dissipation rates of boscalid [2-chloro-N-(4' -chlorobiphenyl-2-yl)nicotinamide], pyraclostrobin [methyl 2-[1-(4-chlorophenyl) pyrazol-3-yloxymethyl]-N-methoxycarbanilate], lufenuron [(RS)-1-[2,5-dichloro-4-(1,1,2,3,3,3-hexafluoropropoxy)phenyl]-3-(2,6-difluorobenzoyl)urea] and lambda-cyhalothrin [(R)-cyano(3-phenoxyphenyl)methyl (1S,3S)-rel-3-[(1Z)-2-chloro-3,3,3-trifluoro-1-propenyl]-2,2-dimethylcyclopropanecarboxylate] in green beans and spring onions under Egyptian field conditions were studied. Field trials were carried out in 2008 in a Blue Nile farm, located at 70 kilometer (km) from Cairo (Egypt). The pesticides were sprayed at the recommended rate and samples were collected at pre-determined intervals. After treatment (T(0)) the pesticide residues in green beans were 7 times lower than in spring onions. This is due to a different structure of vegetable plant in the two crops. In spring onions, half-life (t(1/2)) of pyraclostrobin and lufenuron was 3.1 days and 9.8 days respectively. At day 14th (T(14)) after treatment boscalid residues were below the Maximum Residue Limit (MRL) (0.34 versus 0.5 mg/kg), pyraclostrobin and lambda -cyhalothrin residues were not detectable (ND), while lufenuron residues were above the MRL (0.06 versus 0.02 mg/kg). In green beans, at T(0), levels of boscalid, lufenuron and lambda -cyhalothrin were below the MRL (0.28 versus 2 mg/kg; ND versus 0.02 mg/kg; 0.06 versus 0.2 mg/kg, respectively) while, after 7 days treatment (T(7)) pyraclostrobin residues were above the MRL (0.03 versus 0.02 mg/kg). However, after 14 days the residue level could go below the MRL (0.02 mg/kg), as observed in spring onions.

Topics: Benzamides; Biphenyl Compounds; Carbamates; Fabaceae; Food Contamination; Half-Life; Niacinamide; Nitriles; Onions; Pesticide Residues; Pyrazoles; Pyrethrins; Strobilurins