Activity of Chloroformic Extract from Salvia connivens (Lamiales: Lamiaceae) and Its Principal Compounds against Spodoptera frugiperda (Lepidoptera: Noctuidae)

Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) is one of the most damaging pests in maize crops. In order to manage it, synthetic insecticides such as diamides, neonicotinoids, and pyrethroids are used, but they present a risk for humans and the environment. Investigations of safer alternatives include the use of natural extracts. Thus, this research evaluated the effects of chloroform extract (CHCl3Sc) (5000, 4000, 2000, 1000, and 500 ppm) on aerial parts of Salvia connivens and of nonanal and pyrocatechol (1000, 600, 400, and 80 ppm) on S. frugiperda mortality, duration of the larva and pupae phases, and pupae weight after 24 h. The second instars of S. frugiperda larvae were fed an artificial diet incorporating the extract and compounds. The CHCl3Sc had insecticidal activity against S. frugiperda, showing an LC50 of 1504 ppm. Insectistatic activity began at 1000 ppm, increasing pupal and larval duration in 7.6 and 1.4 days, respectively. Pyrocatechol and nonanal were found in this extract. The first did not have any significant difference in larval or pupal mortalities. On the other hand, insectistatic activity was shown at 500 ppm, increasing the larval duration by 1.7 days compared with the control. In the case of nonanal, the insecticide activity was LC50 of 200 ppm, and insectistatic activity started at 80 ppm, increasing larval duration by 3.2 days compared with the control and reducing pupal weight by 3.4%. The results show that chloroformic extract had insecticidal and insectistatic activities against S. frugiperda; nonanal was an aldehyde compound present in this extract, which confers insecticidal and insectistatic activities against this pest.

Aphicidal activities of Moroccan Bacillus thuringiensis strains against cotton aphid (Aphis gossypii)

The objective of this study was to evaluate the insecticidal effect of toxins from Moroccan Bacillus thuringiensis strains (Berliner) (Bt) on Aphis gossypii (Homoptera: Aphididae). Aphis gossypii is one of the most pests of Moroccan crops. Their management is based traditionally on using chemical products. Some of them are well known to be potentially toxic to the environment and human health. Therefore, alternative strategies for aphid management in crops have been developed in recent years, including a biological control using toxins of bacterial strains. In this study, the artificial diet bioassay was used to screen the aphicidal effect of 82 Bt toxins against first instar nymphs and third instar nymphs of A. gossypii. Among the examined Bt strains, eleven showed a high insecticide activity against A. gossypii stages. In addition, the assessment of the lethal concentration (LC50) of selected Bt revealed that the local BtA4, BtA1 and Bt21.6 exhibited higher insecticidal activity against first instar nymphs of A. gossypii (LC50 (BtA4)=0.15, LC50 (BtA1)=0.23 and LC50 (Bt21.6)=0.25 mg/ml) and the selected strains BtB6, BtA10 and Bt21.6 exhibited the relatively best activity third instar nymphs of A. gossypii (LC50 (BtB6)= 0.48, LC50 (BtA10)= 0.79 and LC50 (Bt21.6)= 1.14 mg/ml) of A. gossypii. Therefore, the results of this study indicate that the selected B. thuringiensis strains have great potential to be used in the integrated A. gossypii management.

Isolation, Purification and Elucidation of Stigmasterol and β-Sitosterol Glucosides from the Stems of Solenostemma argel Grown in Sudan and their Application as Insecticides

Two new compounds were isolated from the chloroform extract fraction of stems of Solenostemma argel, purified by column chromatography and elucidated by phytochemical and spectroscopic methods as Stigmasterol and β-sitosterol glucoside. Chloroform had the highest insecticide activity against the growth of the third larval instar of Tribolium castaneum used as a test insect, when it was compared with n-hexane, ethyl acetate, n-butanol and water extracts.

Insecticidal Activity of Essential Oil of Syzygium Aromaticum Flower in Drosophila

A comprehensive investigation regarding insecticides' mechanism of action on agriculture- and medically-important insects is an important issue to consider. This study aimed to investigate the insecticidal activity of essential oil of Syzygium aromaticum flower (EOSF) using Drosophila melanogaster as an in vivo insect model platform. EOSF was used as a proof-of-concept natural product since it has been reported to exert insecticide activity on certain harmful insects. EOSF was prepared by the water distillation method, and the essential oil is then used to identify its effects on the mortality rate and the locomotor activity of Drosophila. Our results demonstrated that both males and females of D. melanogaster were succumbed immediately, in a dose-response manner, upon EOSF exposure. A slight discrepancy was evident in the effect of EOSF on the mortality rate of males compared to their females' counterparts, thus delineating the possible sex-dependent effect of EOSF on D. melanogaster. Further, decreased locomotor activity was observed on both male and female Drosophila upon EOSF exposure. Overall, it was concluded that EOSF (10 μl, 100 μl, and 1000 μl concentrations) produced insecticidal activity in D. melanogaster.

Nootkatone Is an Effective Repellent against Aedes aegypti and Aedes albopictus

We tested a nootkatone product for insecticide activity against the most prominent vectors of Zika virus (ZIKV), Aedes aegypti, and Aedes albopictus. We tested the permethrin-resistant (PERM-R) Vergel strain of A. aegypti and the permethrin-susceptible (PERM-S) New Orleans strain of A. aegypti to determine if insecticide resistance affected their susceptibility to nootkatone. Bottle bioassays showed that the PERM-S strain (New Orleans) was more susceptible to nootkatone than the confirmed A. aegypti permethrin-resistant (PERM-R) strain, Vergel. The A. albopictus strain ATM-NJ95 was a known PERM-S strain and Coatzacoalcos permethrin susceptibility was unknown but proved to be similar to the ATM-NJ95 PERM-S phenotype. The A. albopictus strains (ATM-NJ95 and Coatzacoalcos) were as susceptible to nootkatone as the New Orleans strain. Bottle bioassays conducted with ZIKV-infected mosquitoes showed that the New Orleans (PERM-S) strain was as susceptible to nootkatone as the mock-infected controls, but the PERM-R strain was less susceptible to nootkatone than the mock-infected controls. Repellency/irritancy and biting inhibition bioassays (RIBB) of A. aegypti determined whether the nootkatone-treated arms of three human subjects prevented uninfected A. aegypti mosquitoes from being attracted to the test subjects and blood-feeding on them. The RIBB analyses data calculated the spatial activity index (SAI) and biting inhibition factor (BI) of A. aegypti at different nootkatone concentrations and then compared the SAI and BI of existing repellency products. We concluded that nootkatone repelled mosquitoes at a rate comparable to 7% DEET or 5% picaridin and has the potential to be an efficacious repellent against adult A. aegypti mosquitoes.

Insecticidal activity ofGallesia integrifolia (Phytolaccaceae) essential oil

This study evaluated the insecticidal activity of Gallesia integrifoliaessential oil from fruits, leaves, and flowers against Aedes aegyptilarvae and pupae. The essential oil was obtained by hydrodistillation and characterized by gas chromatography-mass spectrometry. Sulfur compounds represented 95 to 99% of the essential oil from fruits, leaves, and flowers. Essential oil major compounds were 2,8-dithianonane (52.6%) in fruits, 3,5-dithiahexanol-5,5-dioxide (38.9%) in leaves, and methionine ethyl ester (45.3%) in flowers. The essential oils showed high activity against larvae, and low for pupae withLC99.9of 5.87 and 1476.67μg/mL from fruits; 0.0096 and 348.33 μg/mL from leaves and 0.021and 342.84 μg/mL from flowers, respectively. The main compound with insecticide activity is probably n-ethyl-1,3-dithioisoindole, from isoindole organothiophosphate class, found in greater amount in flower and leaf essential oil. The great insecticide activity of G. integrifoliaessential oil suggests that this product is a natural insecticide.

Effectiveness Test of Piper methysticum Extract Against Crocidolomia pavonana larvae

Application synthetic insecticide with high frequency and continuously can give to negative impact. Alternative control which secures is botanical insecticide. This research aimed to effectiveness tests of P. methysticum plant against C. pavonana larvae using root and leaves this plant. The tested insecticide activity including mortality and feeding inhibition tests. The extract was tested at five concentration levels and repeated five times. The results showed that P. methysticum root extract was able to cause C. pavonana larvae mortality of 94% with a concentration of 419.7 gram/100 ml in water meanwhile, the testing using leaves extract causes mortality 98% from concentration 342 gr/100 ml in water. The feeding inhibition test showed the P. methysticum roots extract give effect with very weak criteria at some concentrations used a no choice method while Leaves extract P. methysticum does not show feeding inhibition.

Analgesic and neuromotor effects of two extracts of Zanthoxylum rhoifolium (Rutaceae) in the Swiss albino mouse (Mus musculus)

BACKGROUND: Colombia has a high diversity of medicinal plants, including Tachuelo (Zanthoxylum rhoifolium), a tree belonging to the family Rutaceae, which has been attributed an analgesic use by communities of the Colombian southwest. Nevertheless, this species has been scarce studied in Colombia. The studies have been limited to the isolation of compounds with antifungal and insecticide activity, using the leaves, branches, and bark of the plant in aqueous, and organic extracts. Neither pharmacological tests have been carried out, nor the analgesic and neuromotor activity have been tested from preparations with this plant’s fruits. OBJECTIVES: To evaluate the analgesic and neuromotor effect of the aqueous and hexane extract of the fruits of Z. rhoifolium. METHODS: As there were no preliminary reports of this study, the first observation was made through Irwin’s test. The formalin and the rotarod test were performed to determine the analgesic and motor coordination effects, respectively. RESULTS: All the evaluated treatments demonstrated to generate analgesia, anesthesia, passivity, reduction in the alarm reaction, and have antinociceptive activity in the formalin test; while only the high dose of the nonpolar extract generated a deficit in the motor performance of the rodents in the rotarod test. CONCLUSIONS: the antinociceptive effect of the aqueous and hexane extracts of this species’ fruits was demonstrated. The hexane extract generated a neuromotor effect, which validates the ethnobotanical reports on Z. rhoifolium fruits.

Intron-assisted, viroid-based production of insecticidal circular double-stranded RNA in Escherichia coli

ABSTRACTRNA interference (RNAi) is a natural mechanism for protecting against harmful genetic elements and regulating gene expression, which can be artificially triggered by the delivery of homologous double-stranded RNA (dsRNA). This mechanism can be exploited as a highly specific and environmentally friendly pest control strategy. To this aim, systems for producing large amounts of recombinant dsRNA are necessary. We describe a system to efficiently produce large amounts of circular dsRNA in Escherichia coli and demonstrate the efficient insecticidal activity of these molecules against Western corn rootworm (WCR, Diabrotica virgifera virgifera LeConte), a highly damaging pest of corn crops. In our system, the two strands of the dsRNA are expressed in E. coli embedded within the very stable scaffold of Eggplant latent viroid (ELVd), a small circular non-coding RNA. Stability in E. coli of the corresponding plasmids with long inverted repeats was achieved by using a cDNA coding for a group-I autocatalytic intron from Tetrahymena thermophila as a spacer. RNA circularization and large-scale accumulation in E. coli cells was facilitated by co-expression of eggplant tRNA ligase, the enzyme that ligates ELVd during replication in the host plant. The inserted intron efficiently self-spliced from the RNA product during transcription. Circular RNAs containing a dsRNA moiety homologous to smooth septate junction 1 (DvSSJ1) gene exhibited excellent insecticide activity against WCR larvae. Finally, we show that the viroid scaffold can be separated from the final circular dsRNA product using a second T. thermophila self-splicing intron in a permuted form.