Enhancing boll protein synthesis and carbohydrate conversion by the application of exogenous amino acids at the peak flowering stage increased the boll Bt toxin concentration and lint yield in cotton

In Bacillus thuringenesis(Bt) transgenic cotton, the cotton boll has the lowest insecticidal protein content when compared to the other organs. The present study investigated the effects of amino acid spray application at the peak flowering stage on the cotton boll Bt toxin concentration and yield formation. Boll protein synthesis and carbohydrate conversion were also studied to reveal the fundamental mechanism. Three treatments(i.e., CK, the untreated control;LA1, five amino acids;LA2, 21 amino acids) were applied to two Bt cultivars of G. hirsutum(i.e., the hybrid Sikang 3 and the conventional Sikang 1) in the cotton-growing seasons during 2017 and 2018. Amino acid spray application at the peak flowering stage resulted in an increase of 5.2–16.4% in the boll Bt protein concentration and an increase of 5.5–11.3%in the seed cotton yield, but there was no difference between the two amino acid treatments. In addition, amino acid applications led to increases in the amino acid content, soluble protein content, glutamate pyruvate transaminase(GPT)activity, glutamate oxaloacetate transaminase(GOT) activity, glucose content, fructose content and soluble acid invertase(SAI) activity. This study also found that Bt protein content, enhanced boll number and the weight of opened bolls were closely related to carbon and nitrogen metabolism. The Bt protein content had significant linear positive correlations with amino acid and soluble protein contents. Enhanced boll number had significant linear positive correlations with the GPT and GOT activities from 15–25 days after flowering(DAF). The weight of opened bolls from 55–65 DAF had a significant linear positive correlation with the SAI activity. These results indicate that the enhancement of boll protein synthesis and carbohydrate conversion by amino acid application resulted in a simultaneous increase in the boll Bt protein concentration and cotton lint yield.

Study on Chemical Synthesis and Insecticidal Activity of Peptideκ-CTx-btg02

[Objectives]This study was conducted to investigate the chemical synthesis of peptideκ-CTx-btg02.[Methods]Linear peptideκ-CTx-btg02 was synthesized by solid phase peptide synthesis(SPPS).After oxidation and folding of the linear peptide,mass spectrometry identification and high performance liquid chromatography(HPLC)purification were performed.Then,the MTT method and insect injection method were applied to study its insecticidal activity.[Results]The peptideκ-CTx-btg02 was successfully synthesized by the SPPS method,and identified for the formation of disulfide bonds by mass spectrometry identification,and the purity after HPLC separation was greater than 95%.The MTT experiment showed that the peptideκ-CTx-btg02 could inhibit the growth of insect cells sf9,with a half effective dose of 0.13 nM.The insect injection experiment showed that the peptideκ-CTx-btg02 could effectively kill Tenebrio molitor,with a half lethal dose of 15.6 nM.The results of the electrophysiological experiment showed that 10μM peptideκ-CTx-btg02 had no blocking activity on murine acetylcholineα2β3 andα3β4.Therefore,the peptideκ-CTx-btg02 had a good inhibitory effect on the growth of insect cells,highly effective insecticidal activity and weak mammalian toxicity.[Conclusions]This study lays a foundation for the development of new,safe and efficient peptide biological insecticides.

Determination of Acute Lethal Doses of Acetamiprid and Cypermethrin for the Native Bee <i>Apis mellifera</i>(Hymenoptera: Apidae) in Cameroon

Honey bees are important pollinators and are essential in agriculture;as such they get exposed to a wide range of pesticides while foraging in contaminated fields or during the spray of chemical on crops. It is therefore important to know the toxicity and evaluate the impacts of bees’ exposure to these molecules. Acetamiprid and cypermethrin are two pesticides widely used in Cameroon and other countries. The objective of this study was to determine the toxicity of acetamiprid and cypermethrin on the native subspecies of Apis mellifera L. in agricultural areas in Adamaoua-Cameroon and to evaluate the impact on honeybee foragers exposed to lethal and sublethal doses of these two insecticides. The results obtained in laboratory conditions show that acetamiprid and cypermethrin are toxic to A. mellifera. The symptoms of neurotoxicity and first mortality appear 15 min after the ingestion of the high concentrations and about 30 to 45 min after the inoculation of the pesticides through contact route and the mortality increases with the concentration and time. The LC50 of acetamiprid obtained after 24 h are respectively 5.26 ng/μl for the topical application and 4.70 μg/μl by the oral route. At the same time, the LC50 of cypermethrin are respectively 2.27 ng/μl for topical application and 2.68 ng/μl for oral toxicity. For a sustainable agriculture and beekeeping, it is, therefore, important to establish quality measures on these insecticides in the ecosystem and to set up a phyto-pharmacovigilance and awareness system to the population.

Nornicotine-typed insecticides:The potential insecticides with strong activity against Diaphorina citri

Nicotine and nornicotine-typed compounds are well-known for its potential as insecticide.Some researches have shown that nicotine was highly toxic to Diaphorina citri Kuwayama,an invasive and fast spreading pest.Here we report the effects of nornicotine-typed insecticide against D.citri.Novel compounds A1-A8,B1-B28,C1-C18 and D1-D12 were synthesized by reported procedure.And bioassays indicated that some of these compounds exhibited good effects against D.citri.Compounds B2,B3,B8,B12,B13,B22,C5,C7,D5,and D9 exhibited the mortality up to 100%within 120 h in 50 mg/L.And further data shows that A2-5,A7,B1,B8,B20 and B22 showed rapid insecticidal activities against D.citri in 24 h with the low LC_(50)(LC_(50)<50 mg/L in 24 h,and LC_(50)<30 mg/L in 72 h).Nornicotine-typed derivatives exhibited activity against D.citri,and B8 and B22 exhibited the best insecticidal activity with an LC_(50)of 18.0
1.0,18.2
0.9 mg/L in 24 h,which had the lower cost than nicotine and showed the potential as powerful insecticides.

Chitin synthesis inhibitors： old molecules and new developments

Chitin is the most abundant natural aminopolysaccharide and serves as a structural component of extracellular matrices. It is found in fungal septa, spores, and cell walls, and in arthropod cuticles and peritrophic matrices, squid pens, mollusk shells, nematode egg shells, and some protozoan cyst walls. As prokaryotes, plants and vertebrates including humans do not produce chitin, its synthesis is considered as an attractive target site for fungicides, insecticides, and acaricides. Although no chitin synthesis inhibitor has been developed into a therapeutic drug to treat fungal infections in humans, a larger number of compounds have been successfully launched worldwide to combat arthropod pests in agriculture and forestry. This review summarizes the latest advances on the mode of action of chitin synthesis inhibitors with a special focus on those molecules that act on a postcatalytic step of chitin synthesis.

Synthesis and Crystal Structure of Cis 2-(6- Chloro-3-pyridylmethylamino)-4-chlorophenyl- 5,5-dimethyl-1,3,2-dioxaphosphinane 2-Oxides

The crystal structure of the title compound (C17H19Cl2N2O3P, Mr = 401.21) has been determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group P21/n with a = 6.1648(6), b = 19.943(2), c = 15.268(2) ?, β = 99.220(2)°, V = 1852.8(3) ?3, Z = 4, Dc = 1.438 g/cm3, F(000) = 832, μ(MoKα) = 0.456 mm-1, the final R = 0.0622 and wR = 0.1586 for 3986 observed reflections (I > 2σ(I)). X-ray analysis reveals that the product is a thermodynamically stable cis isomer. The intramolecular hydrogen bond N(2)–H(2A)…O(1) is observed in the title compound.

Design, Synthesis and Biological Activities of Novel Benzoyl Hydrazines Containing Pyrazole

In search of environmentally benign compounds with high biological activity, low toxicity and low resistance, 8 novel benzoyl hydrazines containing pyrazole were designed and synthesized. All compounds were characterized by I H NMR spectra and HRMS. The preliminary results of biological activity assessment indicated that most of title compounds exhibited certain insecticidal activities against M）,thimna separata Walker at 200 mg L-1 but excellent fungicidal activities against six fungus at 50 mg L-1, which were better than the control.

Syntheses of haptens and hapten-protein conjugates for insecticide propoxur and cyhalothrin

A facile procedure was described for the hapten design of the N-methylcarbamate insecticide propoxur.Two new haptens of propoxur(hapten 1a and hapten 1b) were synthesized by introducing appropriate spacers in the pesticide aromatic moiety of the analyte molecular structure.First,the propoxur reacted with nitric acid to yield the intermediate product.Then hapten 1a was prepared via the reduction of the intermediate product,and hapten 1b was formed by the acylation of hapten 1a with succinic anhydride.In addition,we have also developed a simple method to prepare hapten 2 for the pyrethroid insecticide cyhalothrin,which only requires two steps including the reactions of nitration and reduction.Three haptens were coupled to carrier proteins to prepare the corresponding artificial antigens.The molecular structures of these three haptens were identified by 1H NMR and MS,and those of the artificial antigens were confirmed by UV-vis.

Design, Synthesis, and Insecticidal Activity of 1,5-Diphenyl-l-pentanone Analogues

Three series of novel 1,5-diphenyl-l-pentanone derivatives were designed and synthesized. Their structures were characterized by IR, IH NMR techniques, and elemental analysis. The insecticidal activities of the new compounds were preliminarily evaluated. The bioassay results indicated that the compounds Xll--X30 displayed better aphicidal activity against Aphis gossypii than compounds X1--X10 and the lead compound （E）-l,5-diphenyl-1- penten-1-one （A）. The inhibitory rates of compounds X6 and X29 were 100% against Plutella xylostella （L.） at 600 mgoL 1. Compounds X12, X13, X19, X24, X25, X26 and X27 showed higher insecticidal activity against Tetranychus cinnabarinus （Boisduval） at 600 mgoL 1 than the lead compound （A）. Keywords Stellera chamaejasme L, （E）-l,5-diphenyl-l-penten-l-one, analogue, synthesis, design, insecticidal activity

Design, synthesis, insecticidal evaluation and molecular docking studies of cis-nitenpyram analogues bearing diglycine esters

Based on the strategies of receptor structure-guided neonicotinoid design, a series of novel cis-nitenpyram analogues bearing diglycine esters were designed and synthesized. Preliminary bioassays indicated that the insecticidal spectra of the target compounds were expanded compared with our previous work, while all the target compounds presented excellent insecticidal activities against Nilaparvata lugens and Aphis medicagini at 100 mg/L. Among these analogues, 6b showed 100% mortality against Nilaparvata lugens (LC 50 = 0.163 mg/L) and 90% against Aphis medicagini at 4 mg/L. SARs suggested that the insecticidal potency of our designed cis-nitenpyram analogues was dual-controlled by the size and species of the ester groups. The molecular docking simulations revealed that the structural uniqueness of these analogues may lead to a unique molecular recognition and binding mode compared with the previously designed compounds. Introduction of the peptide bond gave rise to more significant hydrogen bonds between the nitenpyram analogues bonding with the amino acid residues of insect nAChRs. The docking results explained the SARs observed in vitro, and shed light on the novel insecticidal mechanism of these cis-nitenpyram analogues.

Synthesis,Crystal Structure and Insecticidal Activity of N-(pyridin-2-ylmethyl)-1-phenyl-1,4,5,6,7,8-hexahydrocyclohepta[c]pyrazole-3-carboxamide

The title compound N-（pyridin-2-ylmethyl）- 1-phenyl- 1,4,5,6,7,8-hexahydrocy-clohepta[c]pyrazole-3-carboxamide 5 （C21I-I22N40, Mr = 346.42） has been synthesized andstructurally characterized by IR, 1H NMR, 13C NMR, H RMS and single-crystal X-raydiffraction. The crystal crystallizes in monoclinic system, space group P21/n with a = 8.668（2）,b = 22.236（4）, c = 9.539（2） A, β = 108.68（3）°, V = 1786.4（7）/k3, Z = 4, Dx= 1.288 g/cm3,F（000） = 736,μ（MoKa） = 0.649 mm^-1, the final R = 0.0354 and wR = 0.0933 with 3234observed reflections with I 〉 2σ（/）. The benzene and pyrazole rings are nearly coplanar with adihedral angle of 50.977（46）°. The dihedral angle between the central pyrazole and pyridinerings is 11.688（46）°. No classical hydrogen bonds were found in the molecules. Two adjacentmolecules in crystal packing of compound 5 were linked by two intramolecularhydrogen-bonding interactions C（15）-H（15）…O（1） to generate a stable structure. Compound 5had weak insecticidal activity against the diamondback moth （Plutella xylostella）, butexhibited good activity against cotton bollworm （Helicoverpa armigera）.

Synthesis of New 13-O-Acylavermectin Bl Aglycones

Six new 13-O-acylavermectin Bl aglycones(3-8) were synthesized from avermectin B1 aglycone and their bioactivities were evaluated against Spodoptera exigua, Spodoptera eridania, Tetranychus urticae and Aphis fabae.

Synthesis and Crystal Structure of 2-Ethoxycarbonylmethyl-8-chloro-3a,4-dihydro-3a-methyl-chromeno[4,3-c]pyrazol-3(2H)-one

The crystal structure of the title compound 2-ethoxycarbonylmethyl-8-chloro-3a,4-dihydro-3a-methyl-chromeno[4,3-c]pyrazol-3（2H）-one（C15H15ClN2O4,Mr = 322.74） has been prepared and determined by single-crystal X-ray diffraction.The crystal is of orthorhombic,space group Pccn with a = 16.7246（10）,b = 19.6626（12）,c = 9.3013（6） ,V = 3058.7（3） 3,Z = 8,Dc = 1.402 g/cm3,μ = 0.269 mm-1,F（000） = 1344,the final R = 0.0506 and wR = 0.1464 for 2568 reflections with I 〉 2σ（I）.In addition,disordered C（14） and C（15） atoms exist in the crystal structure.

Diamide derivatives containing a trifluoromethylpyridine skeleton:Design,synthesis,and insecticidal activity

Diamide derivatives are biologically active molecules that have been widely applied in recent years in research on pesticides,especially insecticides.Using a simple and environmentally friendly scheme,a series of new diamide derivatives containing a trifluoromethylpyridine skeleton was designed,synthesized,and confirmed by^(1)H,^(19)F and^(13)C NMR,and HR-MS.Their insecticidal activities against Plutella xylostella and Helicoverpa armigera were measured and the relationship between structure and activity was investigated.Eight of the title compounds(D2,D5,D10,D21,D28,D29,D30 and D33)showed 100%activity against P.xylostella at 500 mg L^(-1).One compound,D33,still showed 100%activity against P.xylostella at 100 mg L^(-1)and had the lowest LC_(50)(lethal concentration 50%,3.7 mg L^(-1))among the synthesized compounds.Molecular docking analysis revealed that D33 could be thoroughly embedded in the active pocket of the ryanodine receptor via hydrogen bonding in a manner similar to the commercial insecticide chlorantraniliprole.

Synthesis of 5-[5-(α-Naphthyl)-2H-Tetrazol-2-Methylene]-2-Aroylamino-1, 3,4-Thiadiazoles

Introduction Acylthiosemicarbazides have been reported to possess extensive physiological activities. Substituted thiadiazoles are known to exhibit fungicidal and insecticidal activities. Chen Limin and her coworkers reported that the cyclization of 1[5-(3’-pyridyl )-2H-tetrazol-2-acetyl-]-4-acylthiosemicarbazides gave 5-[5-(3’-

cis-Nitenpyram Analogues Containing 1,4-Dihydropyridine： Synthesis, Insecticidal Activities, and Molecular Docking Studies

A novel series of cb-nitenpyram analogues （2a--2p） were designed and prepared by introducing the 1,4-dihydropyridine, with their eis-configuration confirmed by X-ray diffraction. Preliminary bioassays showed that most compounds exhibited good insecticidal activities at 20 mg/L against Aphis medicagini, and analogues 2a and 2d aflbrded the best activity, and both of them had 100% mortality at 4 mg/L. In addition, molecular docking studies were also performed to model the ligand-receptor complexes, and the results explained the structure-activity relationships observed in vitro, which may provide some useful information for future design of new insecticides.

Synthesis analogues of milbemycin and their bioactivity evaluation

Eight new 13-O-aminocarbonylivermectin aglycones and 4＇-O-aminocarbonylivermectin monosaccharide were synthesized from ivermectin agiycone and ivermectin monosaccharide by the selective protection of C5-OH group.Their bioactivities were evaluated against spider mites（Tetranychus cinnabarimts）,aphid（Aphis fabae） and oriental armyworm（Mytliimma sepatara）. Their structures were confirmed by ^1H NMR.MS.

Synthesis of 4″-benzyloxyimino-4″-deoxyavermectin Bla derivatives

Six new 4＂-benzyloxyimino-4＂-deoxyavermectin B la derivatives were synthesized from avermectin Bla by the selective protection of C-5-hydroxy group, oxidation of C-4＂-hydroxy group, and deprotection followed by reaction with O-substituted hydroxylamine hydrochlorides. Their structures were confirmed by IR, 1H NMR, 13C NMR and MS. Insecticidal activities of the derivatives against Phopalosiphum pseudobrassicae, Spodoptera exigua and Pluteua xylosteua were evaluated.

Synthesis of 5-Deoxy-5-Acyloxyiminoavermectin B1 Derivatives

Four 5-deoxy-5-acyloxyiminoavermectin B1 derivatives 4a^d were synthesized via three steps from avermectin B1 and their biological activities were tested against Heliothis armigera, Laphygma exigua and Musca domestica.

Synthesis and Crystal Structure of N-((6-chloropyridin-3-yl)methyl)-6-ethoxy-N-ethyl-3-nitropyridin-2-amine

The title compound N-（（6-chloropyridin-3-yl）methyl）-6-ethoxy-N-ethyl-3-nitropyri-din-2-amine（4） was synthesized by reacting the mixture of 6-chloro-2-ethoxy-3-nitropyridine（1） and 2-chloro-6-ethoxy-3-nitropyridine（2） with 3,and its structure was determined by X-ray single-crystal diffraction.The crystal belongs to the monoclinic system,space group P21/n with a = 7.3441（2）,b = 9.9041（3）,c = 11.7368（3） ,α = 101.410（2）,β = 102.1340（10）,γ = 99.594（2）o,μ = 0.260 mm^-1,Mr = 336.78,V = 798.58（4）（A°）^3,Z = 2,Dc = 1.401g/cm^3,F（000） = 352,T = 296（2） K,R = 0.0210 and wR = 0.1053.