Design, Synthesis, and Biological Activities of Novel 1,3,5-Trimethylpyrazole-Containing Malonamide Derivatives.

New 1,3,5-trimethylpyrazole-containing malonamide derivatives based on pyflubumide were designed, synthesized, and characterized using ¹H-NMR, 13C-NMR, and high-resolution mass spectra (HRMS). The results of preliminary bioassays showed that the target compounds possessed good activities against Tetranychus cinnabarinus, Plutella xylostella, and Aphis craccivora. Most of the target compounds exhibited moderate to good acaricidal activity against Tetranychus cinnabarinus at a concentration of 400 µg/mL, and some showed moderate activity at a concentration of 200 µg/mL; in particular, compounds 8m and 8p exhibited 70.0% mortality. In addition, some of the target compounds exhibited good insecticidal activities against Plutella xylostella at a concentration of 200 µg/mL, especially compounds 8i and 8o, which achieved 100.0% mortality at a concentration of 100 µg/mL. Interestingly, some of the target compounds exhibited potent anti-aphid activity against Aphis craccivora at a concentration of 200 µg/mL; furthermore, compounds 8p and 8q demonstrated 100.0% anti-aphid activity at a concentration of 50 µg/mL. The preliminary analyses of the structure⁻activity relationships (SAR) indicated that the acaricidal and insecticidal activities varied significantly depending on the type of substituent and substitution pattern, which provides guidance for the further investigation of such structural modifications.

Design, synthesis and insecticidal activity of novel hydrocarbylidene nitrohydrazinecarboximidamides.

BACKGROUND: Neonicotinoids, among the most important pesticides in recent decades, have played pivotal roles in controlling agricultural pests. However, the toxicity to some environmentally beneficial insects is a cause of concern. The development of novel insecticides safer to these insects is increasingly urgent. RESULTS: A novel series of hydrocarbylidene nitrohydrazinecarboximidamides were designed and synthesised, starting from S-methylisothiourea sulphate. Preliminary bioassays showed that the target molecules exhibited good activities against Lipaphis erysimi (turnip aphid) and Myzus persicae. As shown by initial insecticidal activity data, most of the target compounds had moderate to excellent activities at a concentration of 600 mg L-1 against L. erysimi, and the lethal rate of most compounds exceeded 90%. They were also highly effective against M. persicae. Some of them have shown excellent insecticidal activities, for example, the LC50 values of compounds Ie-02 to Ie-07 were found to be 3.8, 3.0, 2.5, 3.1, 4.1 and 4.0 mg L-1 respectively. CONCLUSION: Structure-activity relationship analysis indicated that a suitable flexible alkyl chain at the imine point and a Cl-substituted pyridine ring are the most crucial factors affecting the activity. © 2017 Society of Chemical Industry.

Design, synthesis, and insecticidal activities of phthalamides containing a hydrazone substructure.

Fluobendiamide is the first commercialized artificial synthetic insecticide acting on the ryanodine receptor. This new molecule possesses a combination of excellent insecticidal activity and eco-friendly characteristics with a skeleton structure of phthalamide. In this study, we incorporated hydrazone, present in many pesticidal compounds reported during the last two decades, into phthalamide derivatives via Schiff-base condensation and aminolysis to obtain 21 new compounds; these compounds were characterized by proton nuclear magnetic resonance ((1)H NMR), infrared spectroscopy (IR), and high-resolution mass spectrometry (HRMS) or elemental analysis. A preliminary bioassay against peach aphids ( Myzus persicae ) revealed that the title compounds exhibited good stomach toxicity at 600 mg/L. Twelve new compounds were found to display higher activity than postive control flubendiamide (LC(50) = 184.099 mg/L), however, LC(50) was less than 100 mg/L only for compounds 4e, 4o, 4s, 4t (59-77 mg/L). That is, combinations of a p-fluorophenyl or (methyl)thienyl group at the Ar position with an isopropyl or cyclohexyl group at the R position might improve the lethality of the designed phthalamide derivative. Preliminary results of a bioassay at 600 mg/L against diamondback moth ( Plutella xylostella , Linnaeus) showed that only the title compound 4e possessed good larvicidal activity. On comparison of the bioassay results of stomach toxicity and larvicidal activity, it is noteworthy that the compound incorporating phenylpyrazolyl exhibited good larvicidal activity and poor stomach activity.

Synthesis and herbicidal activity of 12-(aryloxyacyloxyimino)-1,15-pentadecanlactone derivatives.

A series of novel 12-(aryloxyacyloxyimino)-1,15-pentadecanlactone derivatives (3) were synthesized, and their structures including configuration of C=N bond were confirmed by (1)H NMR, elemental analysis and X-ray diffraction analysis. The bioassay showed that some of them exhibited excellent herbicidal activity against Amaranthus tricolor L. The activity of compounds 3 except compounds 3A1-2 was much higher than the commercial herbicide 2,4-D and the activity of about half of compounds 3 was comparable to the commercial herbicide tribenuron-methyl. The further bioassay showed that the representative of compounds 3, 3A1-12, exhibited excellent herbicidal activity not only against dicotyledon, such as Amaranthus tricolor L., Cucumis sativus L., Glycine max L., and Phaseolus radiatus L., but also against monocotyledon, such as Zea mays L. and Oryza sativa L.

Selection and heritability of resistance to Bacillus thuringiensis subsp kurstaki and transgenic cotton in Helicoverpa armigera (Lepidoptera: Noctuidae).

Compared with an unselected susceptible population, a cotton bollworm, Helicoverpa armigera (Hübner), population selected for 22 generations with transgenic cotton leaves (modified Cry1A) in the laboratory developed 11.0-fold resistance to Cry1Ac (one single-protein product MVPII). Resistance to Bacillus thuringiensis Berliner subsp kurstaki (Btk) was selected for 22 generations with a 5.2-fold increase in LC50. The estimated realized heritabilities (h2) of resistance for transgenic-cotton- and Btk-selected populations were 0.1008 and 0.2341, respectively. This reflects the higher phenotypic variation in response to Cry1Ac in the transgenic-cotton-selected population. This variation may have been caused by differences in protein toxin levels expressed in different growth stages of the transgenic cotton. Because of the different slopes of the probit regression lines between Cry1Ac and Btk, the estimated realized h2 cannot be used visually to compare resistance development to Cry1Ac and Btk in H armigera. Thus, the response quotient (Q) of resistance was also estimated. The Q values of resistance for transgenic-cotton- and Btk-selected populations were 0.0763 and 0.0836, respectively. This showed that the rate of resistance development would be similar in both selection populations. This result indicates that the selection of resistance using transgenic cotton is different from that selected using the single toxin. Resistance risk to transgenic cotton and Btk in field populations was assessed assuming different pressures of selection by using the estimated h2. Assuming the h2 of resistance in a field population was half of the estimated h2, and the population received prolonged and uniform exposure to transgenic cotton or Btk causing >70% mortality in each generation, we predicted that resistance would increase 10-fold after <23 generations for Cry1Ac in transgenic cotton-selected-populations and after <21 generations for Btk in Btk-selected populations. Cross-resistance would be expected after <48 generations for Btk in transgenic-cotton-selected populations and after <21 generations for Cry1Ac in Btk-selected population. The results show that the potential to evolve resistance is similar in both transgenic-cotton- and Btk-selected populations, but that cross-resistance development to Btk is slower in transgenic-cotton-selected populations than cross-resistance development to Cry1Ac in Btk-selected populations.