Metabolomic Approaches in Assessing the Insecticidal Activity of the Extracts from Argemone ochroleuca Sweet (Papaveraceae) Against Three Diverse Crop Pests of Economic Importance.

For years, crop protection from pest attack, has been dominated by the use of synthetic insecticides. However, many of them can cause severe environmental problems and human health. In this context, the use of plant extracts constitutes an alternative to avoid this kind of contaminants. In this work, we investigated the chemical constituents and insecticidal activity of different extracts of leaves and stems of Argemone ochroleuca Sweet (Papaveraceae) against three economically important pests Sitophilos zeamais (Coleoptera:Curculionidae), Galleria mellonella (Lepidoptera:Pyralidae) and Xyleborus ferrugineus (Coleoptera:Scolytidae). A GC-MS analysis mostly revealed the presence benzylisoquinoline alkaloids such as allocryptopine, protopine, among others. For the insecticidal activity, after nine hours of contact, the methanolic leaves extract showed a 100 % of mortality, followed by the dichloromethane stems extract with up to 93 % of mortality. The results suggest that the benzylisoquinoline alkaloids are involved in the insecticidal activity through the octopaminergic system of the tested insects.

Larvicidal activity of hexane extract, fatty acids, and methyl esters from Tecoma stans pericarps against Culex quinquefasciatus.

Culex quinquefasciatus (Diptera: Culicidae) is responsible for the transmission of lymphatic filariasis. The search for natural sources of new insecticides to control mosquitoes has intensified in recent years. Tecoma stans is an exotic species in Brazil, known as 'ipê de jardim'. T. stans pericarps were extracted with hexane in Soxhlet apparatus, and fatty acids (FA) and methyl esters (FAME) were obtained by transesterification reaction of hexane extract (HE). HE, FA, and FAME were evaluated against 3rd. and 4th. instar larvae of Culex quinquefasciatus. Analysis by gas chromatography-mass spectrometry (GC/MS) identified the hydrocarbon nonacosane (81.69%) as the major compound in HE, and linolenic (16.89%), linoleic (16.83%), and palmitic acids (21.00%) were predominant in FA. FA and HE, at a concentration of 250 µg/mL, promoted mortality of 81.67% and 68.66% of larvae, respectively. HE and FA obtained from T. stans pericarps have larvicidal potential for the control of C. quinquefasciatus.

Streptomyces derivatives as an insecticide: Current perspectives, challenges and future research needs for mosquito control.

The pervasiveness of arboviruses in wreaking havoc on public health has lingered on international health agendas. A scarcity of mosquito-borne disease vaccines and therapies demands prompt attention, as billions of people worldwide are at risk of infections. It is widely known that vector control continues, and in some diseases, remains the only resort in suppressing disease transmissions we presently possess at its disposal. But the use of commercial insecticides is being crippled by the widespread insecticide resistance, which greatly menaces their efficacies, toxicological repercussions such as environmental pollution and human health risk. Rather, an environmentally benign technique of employing Streptomyces isolates from settings such as terrestrial soils, marine sediments, and mangrove soils for Culicidae management has recently received a lot of positive attention. Streptomyces' capacities to produce a wide range of bioactive secondary metabolites that contribute to pharmaceutical, agricultural and veterinarian, Streptomyces-derived bioactive compounds are increasingly being considered for use in vector control. Herein, we compiled all of the available datasets on the effectiveness of Streptomyces-derived compounds against major mosquito vectors of medical importance. Aedes, Anopheles, and Culex are used to assess the toxicity of crude extracts or fractions. This paper reviewed the promising ovicidal, larvicidal, and pupacidal effects of different Streptomyces strains. Notably, no research into the adulticidal effect of Streptomyces-derived compounds has yet been done. Aside from the genetic makeup, the production of secondary metabolites from Streptomyces depends on the growing conditions. And that, to optimise the maximum yield of highly potent bioactive compounds being extracted, solvents' choice is of paramount importance. Thus, both cultivation parameters and the choice of organic solvents for secondary metabolites extraction will be discussed. Furthermore, biases derived from different studies have implied the need for standardizing experimental procedures. While entomological data should be collected consistently across all studies to expedite evidence-based policymaking of bioinsecticides, the quality of data from vector control interventions - particularly the experimental design, execution, analysis, and presentation of results of vector control studies - will be thoroughly reviewed. Lastly, to promote consistency and reliability, these knowledge gaps are identified, along with a discussion of current perspectives on vector control, global bioinsecticide trends, challenges on commercializing bioinsecticides and future research needs.

Larvicidal activity of Brunfelsia uniflora extracts on Aedes aegypti larvae.

The aim of this study was to evaluate the chemical composition and the larvicidal activity of Brunfelsia uniflora leaf and flower extracts against Aedes aegypti larvae. Twenty-four compounds were found in the leaf extract, and the major compounds were phytol (23.1%), 9,12,15-octadecatrienoic acid, ethyl ester (21.3%), and hexadecanoic acid, ethyl ester (12.8%). In the flower extract, twenty-four compounds were also identified and the major compounds were α-amyrin (35.7%), ß-amyrin (16.4%), and (EE)-geranyl linalool (9.6%) by gas chromatography coupled to mass spectrometry. The larvicidal activity was evaluated by larval immersion test. The lethal concentrations (LC) obtained from leaf extract were LC50 = 4.89 and LC99.9 = 11.14 mg/mL and from flower extract were LC50 = 3.82 and LC99.9 = 11.03 mg/mL, and the positive control presented LC50 = 0.40 and LC99.9 = 1.14 mg/mL. Thus, B. uniflora extracts are promising alternatives to control A. aegypti larvae.

Toxicological Stability of Ocimum basilicum Essential Oil and Its Major Components in the Control of Sitophilus zeamais.

Essential oils (EOs) are widely recognized as efficient and safe alternatives for controlling pest insects in foods. However, there is a lack of studies evaluating the toxicological stability of botanical insecticides in stored grains in order to establish criteria of use and ensure your efficiency. The objective of this work was to evaluate the toxicological stability of basil essential oil (O. basilicum) and its linalool and estragole components for Sitophilus zeamais (Motschulsky) adults in corn grains by fumigation. The identification of the chemical compounds of the essential oil was performed with a gas chromatograph coupled to a mass selective detector. Mortality of insects was assessed after 24 h exposure. After storage for six (EO) and two months (linalool and estragole) under different conditions of temperature (5, 20, and 35 °C) and light (with and without exposure to light), its toxicological stability was evaluated. Studies revealed that the essential oil of O. basilicum and its main components exhibited insecticidal potential against adults of S. zeamais. For greater toxicological stability, suitable storage conditions for them include absence of light and temperatures equal to or less than 20 °C.

Efficacy of Noni (Morinda citrifolia L.) Ethanolic Leaf Extract Against German Cockroach (Blattella germanica L.).

<b>Background and Objective:</b> The ethanol extract of noni leaves (<i>Morinda citrifolia</i> L.) can be used as insecticides to control populations of German cockroaches that have been resistant to synthetic insecticides. This study aimed to determine the potency of the ethanol extract of noni leaves to kill and repel German cockroaches and affect the amount of food consumed. <b>Materials and Methods:</b> The methods used in this study were the contact toxicity test, the repellency test and the food consumption test. The noni leaves extract and German cockroach populations were provided in the laboratory. <b>Results:</b> The noni leaves extract concentration of 20% (residue of 3.14 mg cm² ¹) was very effective in killing the standard population and effective in killing the field population of German cockroaches. The sub-lethal concentration noni leaves extract of 0.36% (residue 0.056 mg cm² ¹) and 1.08% (residue 0.169 mg cm² ¹) was very high grade as repellent of German cockroaches. The sub-lethal concentration of noni leaves extract did not inhibit the amount of food consumption in German cockroach populations. <b>Conclusion:</b> Leaves of noni plants can be used as bioinsecticides to control German cockroach populations that have been resistant to commercial insecticides.

Conservation of stored food using plant's extracts. Effect of oregano (Origanum vulgaris) essential oils on the reproduction and development of flour moth (Ephestia kuehniella).

In the search for effective methods of biological control of stored products insect-pests, the essential oil of Origanum vulgaris was extracted using Clevenger apparatus and tested on reproduction and mortality of flour moth Ephestia kuehniella. Bio-insecticide works with a double action mechanism; administered by inhalation in pupae, essential oil affects their pupal development. It also disrupts the reproduction of exuviated adults by extending the preoviposition period and reducing the period of egg laying and fecundity because fecundated females cannot live more than four days compared to control group. Moreover, the essential oil administered by inhalation in adults causes a significant mortality rate compared to control group by reducing their lifespan. A repellent effect against larvae and adults of this pest was noticed in this work. This allowed us ranking this oil as "moderately repulsive".

Evaluation of larvicidal, adulticidal, and anticholinesterase activities of essential oils of Illicium verum Hook. f., Pimenta dioica (L.) Merr., and Myristica fragrans Houtt. against Zika virus vectors.

Aedes aegypti is the vector responsible for transmitting pathogens that cause various infectious diseases, such as dengue, Zika, yellow fever, and chikungunya, worrying health authorities in the tropics. Due to resistance of mosquitoes to synthetic insecticides, the search for more effective insecticidal agents becomes crucial. The aim of this study was to verify the larvicidal, adulticidal, and anticholinesterase activities of the essential oils of the Illicium verum (EOIV), Pimenta dioica (EOPD), and Myristica fragrans (EOMF) against Ae. aegypti. The essential oils (EOs) were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). The larvicidal and adulticidal activities of EOs were evaluated against third instar larvae and Ae. aegypti adult females, respectively, using the procedures of the World Health Organization (WHO) and the anticholinesterase activity of the EOs by the modified Ellman method. The following major components were identified: (E)-anethole (90.1%) for EOIV, methyl eugenol (55.0%) for EOPD, and sabinene (52.1%) for EOMF. All EOs exhibited larvicidal and adulticidal activity against Ae. aegypti. The highest larval mortality was observed in EOMF with LC50 = 28.2 µg mL-1. Adult mortality was observed after 1 (knockdown) and 24 h exposure, with the highest potential established by the EOIV, KC50 = 7.3 µg mg female-1 and LC50 = 10.3 µg mg female-1. EOIV (IC50 = 4800 µg mL-1), EOMF (IC50 = 4510 µg mL-1), and EOPD (IC50 = 1320 µg mL-1) inhibited AChE. EOMF (4130 µg mL-1) and EOPD (IC50 = 3340 µg mL-1) inhibited BChE whereas EOIV showed no inhibition. The EOs were toxic to larvae and adults of Ae. aegypti, as well as being less toxic to humans than the currently used insecticides, opening the possibility of elaboration of a natural, safe, and ecological bioinsecticide for vector control.

Insecticide activity of Baccharis dracunculifolia essential oil against Cochliomyia macellaria (Diptera: Calliphoridae).

The ethnobotanical uses of Brazilian plants for different injuries and diseases conjoined with local rich biodiversity represent an important resource for research and development. This study aimed to characterise BDEO and its in vitro activity on the third instar larvae (L3) of Cochliomyia macellaria. Groups of 20 L3 were placed on filter paper impregnated with increasing concentrations of 5-30% (v/v), equivalent to 0.79-4.77 µL/cm2, solubilised in ethanol or acetone. The major constituents of BDEO were ß-pinene (9.94%), D-limonene (9.59%), ß-nerolidol (7.93%), caryophyllene (7.69%), spathulenol (6.69), α-muurolene (6.74%) and α-pinene (5.31%). Lethal concentrations of 50% for BDEO on C. macellaria (LC50) after 24 and 48 h of exposure were 2.63 and 2.47 µL/cm2 for ethanol and 9.58 and 8.11 µL/cm2 for acetone, respectively. Furthermore, larvae cuticle abnormalities and adult deformity were observed. Our data confirm the effectiveness of BDEO as an ecofriendly product against blowflies.

Potential of the Lectin/Inhibitor Isolated from Crataeva tapia Bark (CrataBL) for Controlling Callosobruchus maculatus Larva Development.

Callosobruchus maculatus is an important predator of cowpeas. Due to infestation during storage, this insect affects the quality of seed and crop yield. This study aimed to investigate the effects of CrataBL, a multifunction protein isolated from Crataeva tapia bark, on C. maculatus larva development. The protein, which is stable even in extreme pH conditions, showed toxic activity, reducing the larval mass 45 and 70% at concentrations of 0.25 and 1.0% (w/w), respectively. Acting as an inhibitor, CrataBL decreased by 39% the activity of cysteine proteinases from larval gut. Conversely, the activity of serine proteinases was increased about 8-fold. The toxic properties of CrataBL may also be attributed to its capacity of binding to glycoproteins or glycosaminoglycans. Such binding interferes with larval metabolism, because CrataBL-FITC was found in the fat body, Malpighian tubules, and feces of larvae. These results demonstrate the potential of this protein for controlling larva development.

Clitocypin, a fungal cysteine protease inhibitor, exerts its insecticidal effect on Colorado potato beetle larvae by inhibiting their digestive cysteine proteases.

Colorado potato beetle (Leptinotarsa decemlineata Say, CPB) is a major potato pest that adapts readily to insecticides. Several types of protease inhibitors have previously been investigated as potential control agents, but with limited success. Recently, cysteine protease inhibitors from parasol mushroom, the macrocypins, were reported to inhibit growth of CPB larvae. To further investigate the insecticidal potential and mode of action of cysteine protease inhibitors of fungal origin, clitocypin, a cysteine protease inhibitor from clouded agaric (Clitocybe nebularis), was evaluated for its lethal effects on CPB larvae. Clitocypin isolated from fruiting bodies and recombinant clitocypin produced in Escherichia coli slowed growth and reduced survival of CPB larvae in a concentration dependent manner. Clitocypin was also expressed by transgenic potato, but only at low levels. Nevertheless, it reduced larval weight gain and delayed development. We have additionally shown that younger larvae are more susceptible to the action of clitocypin. The inhibition of digestive cysteine proteases, intestains, by clitocypin was shown to be the underlying mode of action. Protease inhibitors from mushrooms are confirmed as promising candidates for biopesticides.

Using ichthyotoxic plants as bioinsecticide: A literature review / Uso de plantas ictiotóxicas como bioinseticida: revisão de literatura

ABSTRACTSome ichthyotoxic plants are study object aiming to discover promising substances in the field of Biotechnology, in search of plant extracts which can be used or even transformed into natural insecticides. This paper presents a bibliographical survey in order to check the traditional use of ichthyotoxic plants as bioinsecticide. Among the plants identified as ichthyotoxic, the most cited in traditional use are those from the genera Derris, Serjania, Lonchocarpus, Magonia, and Tephrosia. The survey suggests that ichthyotoxic plant extracts can contain classes of chemical compounds such as isoflavonoids and tannins with a bioinsecticidal effect and, thus, they can be used in Biotechnology, contributing to reduce the use of synthetic insecticides that present a high toxicity level.

RESUMOUso de plantas ictiotóxicas como bioinseticida: revisão de literatura. Algumas plantas ictiotóxicas são objeto de estudos com a finalidade de descobrir substâncias promissoras no campo da Biotecnologia, na busca de extratos vegetais que possam ser usados ou mesmo transformados em inseticidas naturais. Esse artigo apresenta uma pesquisa bibliográfica sobre o uso tradicional de plantas ictiotóxicas como bioinseticida. Entre as plantas identificadas como ictiotóxicas, as mais citadas no uso tradicional são as dos gêneros Derris, Serjania, Lonchocarpus, Magonia e Tephrosia. A pesquisa sugere que extratos de plantas ictiotóxicas podem conter classes de compostos químicos, como isoflavonoides e taninos, com efeito bioinseticida e, assim, podem ser usados na Biotecnologia, contribuindo na redução do uso de inseticidas sintéticos que possuem alto nível de toxicidade.