Chemical composition of Piper gaudichaudianum essential oil and its bioactivity against Lucilia cuprina (Diptera: Calliphoridae)

Synergistic effect of Balanites aegyptiaca essential oil and storage materials on cowpea seeds

The cowpea (Vigna unguiculata L.) is a legume produced and consumed all over Africa and especially in Nigeria. These beans are a major source of protein in the region. The cowpea weevil (Callosobruchus maculatus L.) is a major pest that affects cowpea seeds. Therefore, cowpea farmers need effective non-toxic pesticides to replace synthetic chemicals. The present research tested the effect of Balanites aegyptiaca L. essential oil on cowpea weevils. This research quantified weevil proliferation and cowpea seed qualities. The samples were treated with 5, 10, and 15 mL of B. aegyptiaca essential oil diluted in 1 mL of acetone and stored in five storage materials, i.e., jute bags, polythene bags, sacks, plastic containers, and glass bottles. The study featured a completely randomized design with three replications of each treatment: treatment time – 90 days, storage temperature – 30 ± 5°C, check – 0.125 g of aluminum phosphide, control – acetone. B. aegyptiaca essential oil proved to be an effective insecticide against cowpea weevils. The treatment achieved 100% mortality rate at 10 and 15 mL of B. aegyptiaca essential oil after 72 h of exposure in glass bottles, plastic containers, and jute bags. In addition, B. aegyptiaca essential oil demonstrated a potent activity against oviposition and survival of immature cowpea weevils. Cowpea seeds packaged in glass bottles, plastics containers, and jute bags showed significantly less damage than those stored in sacks and polythene bags. Glass bottles were the best storage material in terms of safety and shelf stability, followed by plastic containers and jute bags. B. aegeptica essential oil has potent insecticidal properties and can be used as pest control during grain storage.

Phenoplasticity of Essential Oils from Two Species of Piper (Piperaceae): Comparing Wild Specimens and Bi-Generational Monoclonal Cultivars

This study tested the hypothesis that “clonal chemical heritability is a crucial factor for the conservation of chemical uniformity of Piper essential oils in controlled monoclonal cultivation”. We asexually propagated first and second-generation clones of two medicinal and aromatic species, Piper gaudichaudianum Kunth and Piper mollicomum Kunth (Piperaceae), for use as experimental models since they show high chemical plasticity in the wild. Leaves from wild specimens of both species, and their respective cultivated specimens, were hydrodistilled in a Clevenger-type apparatus to produce essential oils (EOs). EOs were chemically characterised by GC-MS and GC-FID. The analysis identified 63 compounds in EO of P. mollicomum, which were predominantly monoterpenes, and 59 in EO of P. gaudichaudianum, which were predominantly sesquiterpenes. Evaluation of chemical diversity and oxi-reduction indices showed a loss of chemical homology across the intergenerational cline. Chemometric analysis indicated higher chemical plasticity between wild and intergenerational specimens of P. mollicomum, than for P. gaudichaudianum. EO compounds were significantly less oxidized throughout the generations in both species. Therefore, while clonal heritability is crucial to chemical homology, significant chemical plasticity is likely to occur when cultivated from wild specimens.

Advanced Chemophenetic Analysis of Essential Oil from Leaves of Piper gaudichaudianum Kunth (Piperaceae) Using a New Reduction-Oxidation Index to Explore Seasonal and Circadian Rhythms

The aromatic species Piper gaudichaudianum Kunth (Piperaceae) is widely used in Brazil for medicinal and ritualistic applications. In the current study, chemophenetic patterns were realized across season and circadian rhythm based on the chemical profile of essential oils (EOs) from leaves. Hydrodistilled essential oils were analyzed by GC-MS and GC-FID, and a new calculation of metabolite oxidation level, averaged for each individual molecule component of the EO, was used to explore the patterns of metabolism/biosynthesis. This new index used an intermediate calculation, the 'weighted average redox standard' (S_RO), to enable a value for mixtures of metabolites to be generated, the 'general mixture redox index' (GM_OR). The indices were subjected to a proof-of-concept approach by making comparison to outcomes from multivariate analyses, i.e., PCA and HCA. Chemical analysis demonstrated that the essential oils were dominated by sesquiterpenes, constructed of 15 classes of compound (C-skeletons), and 4 C-skeletons were recognized in the monoterpene group, giving a total of 19. The variation of chemical profiles was distinct at different phenological stages, but stronger chemical variation was evident between day and night as compared to season. Furthermore, due to comprehensive sampling across different regions, nine chemotypes were recognized, including those previously reported. The S_RO and GM_RO indices demonstrate that phenological variation of chemistry is mainly an outcome of redox fluctuations in terpene biosynthesis, changing from day to night. These indices also corroborate that chemical diversity is increased with oxidative metabolism. Lastly, the current study demonstrates pronounced phenotypic plasticity in P. gaudichaudianum, which makes it a suitable candidate to help further our understanding of chemophenetics and chemical ecology.

Nanobiopesticides: development and inseticidal activity of nanoemulsions containing lemongrass or eucalyptus oils

The bioinsecticides, like essential oils, are a promising alternative in pest control. However, these oils have some limitations, such as instability and low solubility. These limitations can be circumvented through nanotechnology, with the nanoemulsification of these compounds. Therefore, the objective of this study was to prepare, characterize and explore the insecticidal activity against adult flies of nanoemulsions containing essential oil of lemongrass or eucalyptus. The nanoemulsions were prepared by the high-energy method and presented droplet size smaller than 125 nm, with polydispersity index of 0.2, pH acid and spherical morphology. The insecticidal activity was evaluated by the Topical Application Method and Exposure Impregnated Paper Exposure, where it was possible to demonstrate a potential insecticidal effect of lemongrass oil in the concentrations of 10, 30 and 50 µL/mL against Musca domestica and Lucilia cuprina and the potentiation of this effect when nanoemulsified this oil against L. cuprina.

Topical Toxicity Profiles of Some Aliphatic and Aromatic Essential Oil Components Against Insecticide-Susceptible and Resistant Strains of German Cockroach (Blattodea: Ectobiidae)

Toxicity profiles of four aliphatic (α-pinene, cyclononanone, limonene, nerolidol), four aromatic (β-thujaplicin, carvacrol, eugenol, tropolone) essential oil components (EOCs), and permethrin were investigated against three strains of German cockroach, Blattella germanica (L.). The strains include a susceptible strain (S), and two multi-resistant strains - strains D and E. Also, a synergism bioassay, using piperonyl butoxide (PBO) was conducted. The most toxic EOCs were aromatic EOCs carvacrol, eugenol, and tropolone, followed by aliphatic EOC limonene; all had LD50 values of <0.7 mg/µl. Four of the EOCs were equally toxic against all the strains, with carvacrol being the most toxic, followed by eugenol, tropolone, and α-pinene. The other four EOCs were more toxic against strain S than against the two resistant strains. Permethrin was significantly more toxic to strain S (LD50 = 0.056 µg/µl) compared with the resistant strains (D = 2.138 µg/µl, E = 1.730 µg/µl). Toxicity of aliphatic EOCs correlated positively with their molecular weight against strain E only, whereas both molecular weight and vapor pressure of aromatic EOCs correlated significantly with toxicity in all strains. Strain D exhibited the greatest resistance (RR of 6.7) to EOCs, and synergism to the aliphatic EOC cyclononanone. Clear synergism with PBO was observed in permethrin against resistant strains, but not in all of the EOCs, suggesting multiple resistance mechanisms in the resistant cockroaches. These findings give insight on the potential of EOCs to be incorporated as parts of an IPM approach to managing insecticide resistant German cockroaches.

Data of insecticide effects of natural compounds against third instar larvae of Cochliomyia macellaria

Morphological biomarkers can be used to establish a diagnosis of fly larvae structural damage and toxicity to target cells by biopesticide candidates. Insecticide activity of natural compounds such as Curcuma longa essential oil (CLLEO) extracted from leaves, and its major constituent α-phellandrene have proven to be a novel biopesticide candidate against third instar larvae (L3) of Cochliomyia macellaria. In this way, groups of 20 L3 were placed on filter paper impregnated with different concentrations of CLLEO, from 0.31 to 2.86 μL/cm² and α-phellandrene, from 0.29 to 1.47 μL/cm². The extracts were solubilized in ethanol. Data shown in this article is related to the research article “Can an overlooked by-product from turmeric industry be effective for myiasis control?” Chaaban et al., 2019. Data on L3 toxicity was observed after 6 and 24h of contact with both extracts, as well as a marked reduction of L3 movement, color changes in the cuticle and progressive darkening in their body. Major cuticle damage and L3 mortality were reported.

Synergistic Toxicity of Plant Essential Oils Combined with Pyrethroid Insecticides against Blow Flies and the House Fly

Blow flies (Diptera: Calliphoridae) and the house fly (Diptera: Muscidae) are filth flies of medical importance, and control of their population is needed. As insecticide applications have resulted in fly resistance, and the exploration of plant essential oils (EOs) has increased against filth flies, this study assessed the combination of EOs with pyrethoids to enhance toxic efficacy. The EOs of five effective plants were screened initially against the house fly (Musca domestica L.). Their chemical constituent was performed using gas chromatography-mass spectrometry (GC-MS) analysis. The main components of Boesenbergia rotunda (Zingiberaceae) rhizome, Curcuma longa (Zingiberaceae) rhizome, Citrus hystrix (Rutaceae) fruit peel, Ocimum gratissimum (Lamiaceae) seed, and Zanthoxylum limonella (Rutaceae) fruit were δ-3-caren (35.25%), β-turmerone (51.68%), β-pinene (26.56%), p-cumic aldehyde (58.21%), and dipentene (60.22%), respectively. The screening test revealed that the three most effective plant EOs were from B. rotunda, C. longa and O. gratissimum, which were selected for the combination with two pyrethroid insecticides (permethrin and deltamethrin), in order to enhance their synergistic efficacy against the blow flies, Chrysomya megacephala Fabricius, Chrysomya rufifacies Macquart, and Lucilia cuprina Wiedemann, and the house fly. Synergistic action was presented in almost all of the flies tested with permenthrin/deltamethrin/EOs mixtures. It was interesting that the combination of deltamethrin with three EOs showed a synergistic effect on all of the tested flies. However, an antagonistic effect was observed in C. megacephala and M. domestica treated with permethrin-B. rotunda and C. megacephala treated with permethrin-O. gratissimum. The LD50 of insecticides decreased when combined with plant EOs. This alternative strategy will be helpful in developing a formula for effective fly control management.

Effects of Tagetes minuta essencial oil on Lucilia cuprina third instar larvae

The activity of Tagetes minuta essential oil (TMEO) was tested against third instar larvae (L3) of the Australian blowfly Lucilia cuprina. We have determined the potential of the T. minuta EO as a new biopesticide candidate. To test this, groups of 20 L3 were placed on filter paper impregnated with ranging concentrations (from 0.19 to 6.36 μL/cm²) of TMEO, solubilized in acetone. Data show in this article is related to research article “Tissue damage and cytotoxic effects of Tagetes minuta essential oil against Lucilia cuprina” Chaaban et al., 2019. Thus, data of cuticle damage, color changes in L3 body and decrease in L3 motility were recorded 24 and 48 h after TMEO contact.

Tissue damage and cytotoxic effects of Tagetes minuta essential oil against Lucilia cuprina

The blowfly Lucilia cuprina has great medico-sanitary and veterinary importance due to the ability of its larval form to develop in decaying organic matter, parasitizing vertebrates. Fly eradication is challenging and the essential oil (EO) of Tagetes minuta (TMEO) have been reported to have therapeutic properties. This study aimed to determine the activity of EO from the aerial parts of T. minuta against third instar larvae (L3) of L. cuprina. Groups of 20 L3 were placed on filter paper, which were impregnated with varying concentrations (0.19; 0.39; 0.79; 1.59; 2.38; 3.18; 4.77; and 6.36 μL/cm²) of TMEO solubilized in acetone, ethanol or Tween 20. Histological tissue damage of TMEO was measured in L3 after 24, 48 and 96 h of exposure. Dihydrotagetone (67.64%), trans-ocimene (16.23%), trans-tagetone (10.14%) and verbenone (2.98%) were obtained as major compounds of TMEO. Lethal concentrations of 50%, 24 and 48 h after TMEO exposure were 1.02 and 0.73 μL/cm² for acetone; 3.37 and 1.75 μL/cm² for ethanol; and 7.46 and 6.11 μL/cm² for Tween 20, respectively. TMEO had a significant L3 mortality of 96.6% in acetone, 48 h after contact. Cuticle abnormalities were observed, as well as the loss of digestive tract architecture and vacuolization in fat bodies. TMEO presented time and concentration-dependent effects against L. cuprina. As our study demonstrated a strong insecticide activity of TMEO, we consider that it could be developed into an ecofriendly product against L. cuprina.

Insecticide activity of Curcuma longa (leaves) essential oil and its major compound α-phellandrene against Lucilia cuprina larvae (Diptera: Calliphoridae): Histological and ultrastructural biomarkers assessment

Lucilia cuprina, known as the Australian blowfly, is of high medico-sanitary and veterinary importance due to its ability to induce myiasis. Synthetic products are the most frequent form of fly control, but their indiscriminate use has selected for resistant populations and accounted for high levels of residues in animal products. This study aimed to assess the effect of essential oil from leaves of Curcuma longa (CLLEO), and its major compound α-phellandrene against L. cuprina L3. An additional goal was to determine the morphological alterations in target organs/tissues through ultrastructural assessment (SEM) and light microscopy, as well as macroscopic damage to cuticle induced by CLLEO. Groups of 20 L3 were placed on filter paper impregnated with increasing concentrations of CLLEO (0.15 to 2.86 μL/cm²) and α-phellandrene (0.29 to 1.47 μL/cm²). Efficacy was determined by quantifying L3 mortality 6, 24 and 48 h after contact with CLLEO and by measuring the structural damage to L3. CLLEO and α-phellandrene inhibited adult emergence by 96.22 and 100%, respectively. Macroscopic cuticle damage, appeared as diffuse pigment and darkening of larval body, was caused by both extracts. The SEM revealed dryness on the cuticle surface, distortion of the sensorial structures and general degeneration in treated L3. Furthermore, alterations in target organs (digestive tract, fat body and brain) were noticed and shall be used as biomarkers in future attempts to elucidate the mechanism of action of these compounds. The vacuolar degeneration and pyknotic profiles observed in the brain tissue of treated larvae with both extracts and the decreased motility within <6 h after treatment leads us to suggest a neurotoxic activity of the products. This work demonstrates the potential use of CLLEO and α-phellandrene as bioinsecticides to be used against L. cuprina, representing an ecofriendly alternative for myiasis control in humans and animals.

Cuticular damage of Lucilia cuprina larvae exposed to Curcuma longa leaves essential oil and its major compound α-phellandrene

Morphological biomarkers as the histopathological assessment and scanning electron microscopy can be used to establish a diagnosis of structure damage and intoxication of target cells by new biopesticide candidate. In this sense, cuticle damage caused by active substances in larvae exposed to biopesticides can help to elucidate the mode action. Thus, insecticide activity analysis of essential oil of Curcuma longa leaves and its major compound α-phellandrene have proven to be a new biopesticide candidate against third instar larvae (L3) of the Australian blowfly Lucilia cuprina. In this way, groups of 20 L3 were placed on filter paper, impregnated with ranging concentrations (from 0.15 to 2.86 μL/cm²) of C. longa leaves EO and (0.29–1.47 μL/cm²) to α-phellandrene. The extracts were solubilized in ethanol. Progressive darkening in the body of L3, marked reduction of movement, color changes in larval cuticle and dead were observed 6 and 24 h after contact with both extracts.