Evaluation of the Toxicity of Satureja intermedia C. A. Mey Essential Oil to Storage and Greenhouse Insect Pests and a Predator Ladybird

Insecticidal Activity of Some Major Essential Oil Components against Metopolophium dirhodum and Its Predators

Essential oils (EOs) are plant metabolites with important insecticidal effects. Nevertheless, information on the efficacy of the major substances on aphids and their natural enemies is still missing. The objective of this paper is, therefore, to identify the efficacy of selected EO majority substances-β-citronellol, carvacrol, isoeugenol, and linalool, including their binary mixtures-on the mortality and fertility of the aphid Metopolophium dirhodum, an important cereal pest. The best efficacy was proven for the binary mixture of β-citronellol and linalool (1:1 ratio), for which the estimated LC50(90) is 0.56(1.58) mL L-1. This binary mixture applied in sublethal concentrations significantly reduced aphid fertility. It was found that the phenomenon can be attributed to β-citronellol, as the females treated with LC30 laid 45.9% fewer nymphs, on average, compared to the control. Although β-citronellol and linalool, including their 1:1 mixture, showed very good efficacy on aphid mortality, they were, on the other hand, very friendly to the larvae of Aphidoletes aphidimyza and Chrysoperla carnea, which are important aphid predators. Based on our results, the newly discovered synergically acting binary mixture β-citronellol/linalool can be recommended as an efficient substance suitable for the further development of botanical insecticides used against aphids.

A new endophytic Penicillium oxalicum with aphicidal activity and its infection mechanism

BACKGROUND

Aphid infestation adversely affects the yield and quality of crops. Rapid reproduction and insecticidal resistance have made controlling aphids in the field challenging. Therefore, the present study investigated the insecticidal property of Penicillium oxalicum (QLhf-1) and its mechanism of action against aphids, Hyalopterus arundimis Fabricius.

RESULTS

Bioassay revealed that the control efficacy of the spores against aphids (86.30% and 89.05% on the third day and fifth day after infection, respectively) were higher than other components, such as the mycelium. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that QLhf-1 invaded the aphid cuticle through spores and used the aphid tissues as a nutrient source for growth and reproduction, causing stiffness and atrophy and a final death. Three extracellular enzymes, lipase, protease, and chitinase had a synergistic effect with spores, and they acted together to complete the infection process by degrading the aphid body wall and accelerating the infection process.

CONCLUSION

The newly discovered endophytic penicillin strain P. oxalicum 'QLhf-1' can effectively kill aphids. The results provided strong evidence for the biological control of aphids, and lay a foundation for the development and utilization of QLhf-1. © 2024 Society of Chemical Industry.

Potential of Thuja occidentalis L. Essential Oil and Water Extracts against Field Crop Pests

Thuja occidentalis L. essential oil (EOTO) and its compounds, such as terpinyl acetate, bornyl acetate, and β-thujone, are claimed to be highly effective against some storage pests, sanitary insects, or pests of fruit trees, while data about its use in protecting field crops are very scarce. There is also a lack of information in the literature about the insecticidal value of water extracts from T. occidentalis (WETOs). Both essential oils (EOs) and water extracts (WEs) from various plants have advantages and disadvantages in terms of their use as insecticides. EOs are generally more effective, but their preparation is more complicated and quite expensive. In turn, WEs are simple to prepare and cheap, but they often have limited effectiveness. Moreover, significant differences in responses exist depending on the species of the donor plant, the method of preparing the extract, its concentration, the species of the pest being controlled, the developmental stage, and even the gender of the pest. The goals of the research were to assess the effect of EOTO and WETOs prepared from dry and fresh matter on the mortality, feeding, and body mass changes of important crop pests, i.e., the black bean aphid, pea leaf weevil, and Colorado potato beetle (CPB), respectively, as well as on the mortality and voracity of non-target organism Asian lady beetle young larvae. EOTO showed significant aphicidal activity with LC50 = 0.8267% and 0.2453% after 42 h of the experiment for nymphs and wingless females of black bean aphid, respectively. Adults of CPB were more resistant to EOTO than aphids, with LC50 values for females equal to 1.5327% and 1.3113% after 48 h and after 72 h of the experiment. There was no significant effect of EOTO on CPB foraging. Calculated LC50 values for pea leaf weevil adults were lower than those for CPB (0.9638% and 0.8573% for males after 12 h and 24 h, respectively). In the case of this pest, a clear reduction in foraging was obtained, with higher concentrations of EOTO resulting in more pronounced reductions in foraging behavior. Concentrations of EOTO above 0.5%, which showed efficacy against the aphid, were lethal to 3-day-old larvae of the Asian lady beetle. WETOs, in turn, showed significant potential in inhibiting adult pea leaf weevil feeding, with very low or no effectiveness in reducing A. fabae and CPB, respectively.

Effects of Seven Plant Essential Oils on the Growth, Development and Feeding Behavior of the Wingless Aphis gossypii Glover

Cotton aphid Aphis gossypii Glover damages plants such as cotton directly by feeding on leaves and indirectly by transmitting viruses and excreting honeydew, which interferes with photosynthesis. The control of A. gossypii is still dominated by the frequent use of insecticides, which leads to a gradual increase in pesticide resistance in A. gossypii. Research is therefore needed on non-pesticide controls. In this study, seven plant essential oils (EOs) of Ocimum sanctum L., Ocimum basilicum L., Ocimum gratissimum L., Mentha piperita L., Mentha arvensis L., Tagetes erecta L., and Lavandula angustifolia Mill. were examined as potential controls for A. gossypii. We used life tables and electrical penetration graphs (EPG) to explore the effects of these EOs on the growth, development, and feeding behavior of A. gossypii, followed by a study of effects of the EOs on honeydew secretion by A. gossypii as a measure of their antifeedant activity. We found that the EOs of O. sanctum, M. piperita, M. arvensis and T. erecta significantly extended the pre-adult developmental period. Also, adult longevity, number of oviposition days, and total fecundity of A. gossypii treated with the EOs of M. arvensis or T. erecta were all significantly reduced. Aphids treated with the EOs of O. sanctum, M. piperita, or L. angustifolia showed significant reductions in their net reproductive rate (R0), intrinsic rate of increase (rm), and finite rate of increase (λ), and significant increases in mean generation time (T). In terms of their effects on the feeding behavior of A. gossypii, all seven EOs significantly reduced the total duration of phloem feeding (E2 waves), the number of phloem-feeding bouts, and the proportion of time spent in secretion of saliva into phloem sieve elements (E1 waves) and phloem feeding (E2). The total duration and number of E1 waves (saliva secretion) were significantly reduced by the EOs of O. sanctum, O. gratissimum, and M. arvensis. For C waves (probing in non-vascular tissues), the total duration spent in this behavior was significantly increased by the EOs of O. gratissimum, M. piperita, and L. angustifolia, but the number of such probing events was increased only by L. angustifolia EO. The EOs of O. basilicum, M. arvensis, and T. erecta significantly increased the total duration of ingestion of xylem sap (G waves), while the total time of mechanical difficulty in stylet penetration (F waves) was increased by M. arvensis. The total duration and number of the non-probing events (Np waves) were significantly increased by EOs of O. sanctum and O. basilicum. After treatment with all seven of these EOs, the area covered by honeydew was significantly reduced compared with the control. Studies have analyzed that EOs of O. sanctum, M. piperita, and T. erecta were most effective, followed by the EOs of M. arvensis and L. angustifolia, and finally the EOs of O. basilicum and O. gratissimum. In the present study, the EOs of O. sanctum, M. piperita, and T. erecta were found to have potential for the development as antifeedants of A. gossypii, and these data provide a basis for future research on non-pesticide chemical control of A. gossypii.

Detection of Specific Volatile Organic Compounds in Tribolium castaneum (Herbst) by Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a major storage pest that could lead to a wide range of damage. Its secretions have a significant impact on the quality of stored grain and food, leading to serious food safety problems such as grain spoilage and food carcinogenesis. This study investigates new detection techniques for grain storage pests to improve grain insect detection in China. The primary volatile organic chemicals (VOCs) in these secretions are identified using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The specific VOCs that are unique to T. castaneum are selected as criteria for determining the presence of T. castaneum in the granary. To obtain more specific VOCs, experiments were designed for the analysis of T. castaneum samples under different extraction times, two types of SPME fibers and two GC-MS devices of different manufacturers. The experimental results showed that 12 VOCs were detected at relatively high levels, seven of which were common and which were not detected in other grains and grain insects. The seven compounds are 1-pentadecene, 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone, 1-hexadecene, cis-9-tetradecen-1-ol, m-cresol and paeonol. These seven compounds can be used as volatile markers to identify the presence of T. castaneum, which could serve as a research foundation for the creation of new techniques for T. castaneum monitoring.

Chemical Profiles and Insecticidal Potential of Essential Oils Isolated from Four Thymus Species against Rhyzopertha dominica (F.)

Although chemical pesticides have been efficiently used to manage insect pest, their overuse has led to environmental contamination and threats to human health, enticing researchers to introduce eco-friendly and effective agents. In this study, the insecticidal effectiveness of essential oils isolated from Thymus species, including T. eriocalyx, T. kotschyanus, T. fallax, and T. vulgaris, was evaluated against the adults of Rhyzopertha dominica. The terpenes p-cymene, 1,8-cineole, linalool, α-terpineol, and carvacrol were the prominent compounds in the hydrodistilled essential oils. All essential oils produced significant fumigant at 24, 48, and 72-exposure times. The energy reserves protein by all essential oils, glycogen by T. kotschyanus and T. vulgaris, and lipid by T. fallax and T. vulgaris were significantly decreased compared to control. All essential oils except T. vulgaris affected the amylolytic and proteolytic activity of the pest. The pest increased the α- and β-esterase enzyme activity in response to the essential oils. Nutritional indices of adults were also affected by essential oils, in which feeding deterrence index was calculated from 20.41% to 61.11%. Accordingly, based on lethal and extensive sub-lethal insecticidal activities, T. eriocalyx, T. kotschyanus, T. fallax, and T. vulgaris essential oils can be considered as efficient agents for R. dominica management.

Toxicity, Deterrent and Repellent Activities of Four Essential Oils on Aphis punicae (Hemiptera: Aphididae)

Chemical insecticides have many harmful effects, including as foodborne residues and environmental contaminants, as well as side effects on natural enemies and serious risks for human health. The use of plant-derived essential oils (EOs) as effective bio-agents has become an essential component of integrated pest management. In this study, the contact toxicity, deterrent, and repellent activities were evaluated for essential oils obtained from Mentha piperita, Mentha longifolia, Salvia officinalis, and Salvia rosmarinus, grown at high altitudes in the Taif region, KSA, on Aphis punicae. Furthermore, the toxicity of these EOs against the predator Coccinella undecimpunctata was estimated. A total of 17, 14, 16, and 26 compounds were identified in the EOs of M. piperita, M. longifolia, S. officinalis, and S. rosmarinus, respectively. They showed a variation in the major compounds: M. piperita (Carvone, 61.16%), M. longifolia (Pulegone, 48.6%), S. officinalis (Eucalyptol, 33.52%), and S. rosmarinus (α-pinene, 36.65%). A contact toxicity test on A. punicae imago and C. undecimpunctata larvae showed that LC₅₀ were approximately four-fold greater for all tested EOs towards aphids compared to towards the predator, while the two species of Salvia sp. were more effective than the other two species of Mentha sp. The LC₅₀ values on A. punicae ranged from 1.57 to 2.97 µg/mL, while on C. undecimpunctata larvae, they ranged from 5.96 to 10.33 µg/mL. Furthermore, the EOs of two species of Salvia sp. showed excellent repellence and deterrence against A. punicae. In conclusion, the tested EOs, especially those from Salvia sp., have been shown to be promising natural aphicides, repellent, and deterrent against A. punicae, and they are safe for important insect predators.

Susceptibility of Tribolium castaneum (Coleoptera: Tenebrionidae) to the Fumigation of Two Essential Satureja Oils: Optimization and Modeling

Due to the numerous side effects of synthetic pesticides, including environmental pollution, threats to human health, harmful effects on non-target organisms and pest resistance, the use of alternative healthy, available and efficient agents in pest management strategies is necessary. In this paper, the susceptibility of the cosmopolitan, polyphagous, stored-product pest Tribolium castaneum (red flour beetle) to the fumigation of the essential oils of two important medicinal and food additive plants, Satureja hortensis and S. intermedia, was investigated. The insecticidal properties of the essential oils were modeled and optimized using response surface methodology. It was found that a maximum significant mortality of 94.72% and 92.97% could be achieved within 72 h with the applications of 55.15 µL/L of S. hortensis (with the linear model) and 58.82 µL/L of S. intermedia (with the quadratic model), respectively. There were insecticidal terpenes and phenylpropanoids in both essential oils, including thymol (50.8%), carvacrol (11.2%) and p-cymene (13.4%), in the S. intermedia and estragole (68.0%) and methyl eugenol (5.6%) in the S. hortensis. It was suggested that the essential oils of S. hortensis and S. intermedia could be offered as promising pesticidal agents against T. castaneum for further studies in the management of such pests instead of detrimental synthetic pesticides.

Acaricidal, Insecticidal, and Nematicidal Efficiency of Essential Oils Isolated from the Satureja Genus

The overuse of synthetic pesticides in plant protection strategies has resulted in numerous side effects, including environmental contamination, food staff residues, and a threat to non-target organisms. Several studies have been performed to assess the pesticidal effects of plant-derived essential oils and their components, as partially safe and effective agents, on economically important pests. The essential oils isolated from Satureja species are being used in medicinal, cosmetic, and food industries. Their great potential in pest management is promising, which is related to high amounts of terpenes presented in this genus. This review is focused on the acute and chronic acaricidal, insecticidal, and nematicidal effects of Satureja essential oil and their main components. The effects of eighteen Satureja species are documented, considering lethality, repellency, developmental inhibitory, and adverse effects on the feeding, life cycle, oviposition, and egg hatching. Further, the biochemical impairment, including impairments in esterases, acetylcholinesterase, and cytochrome P450 monooxygenases functions, are also considered. Finally, encapsulation and emulsification methods, based on controlled-release techniques, are suggested to overcome the low persistence and water solubility restrictions of these biopesticides. The present review offers Satureja essential oils and their major components as valuable alternatives to synthetic pesticides in the future of pest management.

Analysis of the Essential Oils of Eucalyptus camaldulensis Dehnh. and E. viminalis Labill. as a Contribution to Fortify Their Insecticidal Application

The use of synthetic chemicals, with harmful effects on the environment and human health, is the principal strategy in the management of stored-product insect pests such as Oryzaephilus surinamensis and Sitophilus oryzae. Various studies in recent years have highlighted the possibility of using plant essential oils as available and low-risk factors in insect pest management. Therefore, in the present study, the possibility of controlling O. surinamensis and S. oryzae was investigated using Eucalyptus camaldulensis and Eucalyptus viminalis leaf essential oils. The essential oils were obtained by hydrodistillation of the leaves of the 2 Eucalyptus species, and the chemical compositions were determined by gas chromatographic-mass spectral analysis. The essential oil of E. camaldulensis was dominated by p-cymene (24.8%), cryptone (18.9%), and spathulenol (12.4%), while the major components in E. viminalis essential oil were 1,8-cineole (51.6%) and α-pinene (15.8%). The essential oils displayed promising fumigant toxicity against insect pests, which was positively dependent on utilized concentrations and exposure times. Oryzaephilus surinamensis, with low median lethal concentrations, was more susceptible than S. oryzae to the essential oils after 24, 48, and 72 hours. Also, E. viminalis essential oil, with a high level of insecticidal monoterpenes such as 1,8-cineole and α-pinene, was more toxic to insect pests than E. camaldulensis oil. According to the results of the current study, E. camaldulensis and E. viminalis essential oils, rich in insecticidal terpenes, can be alternative candidates to synthetic chemicals in the management of O. surinamensis and S. oryzae.