The inappropriate application of imidacloprid destroys the ability of predatory natural enemies to control pests in the food chain: A case study of the feeding behavior of Orius similis on Frankliniella occidentalis.

Insecticides are an indispensable and important tool for agricultural production. However, the inappropriate application of insecticides can cause damage to the food chain and ecosystem. Orius similis is an important predatory and natural enemy of Frankliniella occidentalis. Imidacloprid is widely used to control pests, but will inevitably exert adverse effects on O. similis. In order to determine the effect of different imidacloprid treatments on the ability of O. similis to prey on the 2nd-instar nymphs of F. occidentalis, we determined the toxicity and predation of imidacloprid on different stages of O. similis under contact and ingestion treatments. In addition, we used the Holling disc equation to evaluate the ability of O. similis to search and exhibit predatory activity following contact and ingestion treatments. Analysis showed that the highest LC10 and LC20 values for imidacloprid contact and ingestion toxicity treatment were 17.06 mg/L and 23.74 mg/L, respectively. Both imidacloprid treatments led toa reduction in the predatory of O. similis on prey. The functional responses of the 3rd to 5th instar nymphs, along with female and male O. similis adults to the 2nd-instar nymphs of F. occidentalis were consistent with the Holling type II response following contact and ingestion with imidacloprid. However, following imidacloprid treatment, the handing time (Th) of O. similis with single F. occidentalis was prolonged and the instantaneous attack rate (a) was reduced after imidacloprid treatment. The predatory capacity (a/Th) of female O. similis adults when treated with the LC10 concentration of imidacloprid by ingestion was 52.85; this was lower than that of the LC10 concentration of imidacloprid in the contact treatment (57.67). The extent of predation of O. similis on the 2nd-instar nymphs of F. occidentalis was positively correlated with prey density, although the search effect was negatively correlated with prey density. The most extensive search effect was exhibited by adult O. similis females. Simulations with the Hessell-Varley interference model showed that an increase in the number of O. similis would reduce search efficiency regardless of whether they were treated with imidacloprid or not. Thus, O. similis, especially female adults, exhibited strong potential for controlling the 2nd-instar nymphs of F. occidentalis. The toxicity of ingestion following treatment with the same concentration of imidacloprid in O. similis was greater than that of contact treatment. When using O. similis to control F. occidentalis in the field, we should increase the number of female adults released, and prolong the interval between imidacloprid treatment and O. similis exposure. This strategy will improve the control ability of O. similis, coordinate both chemical and biological control, reduce the impact of pesticides on the environment, and improve the efficiency of agricultural production.

Role of odorant binding protein C12 in the response of Tribolium castaneum to chemical agents.

Tribolium castaneum is a worldwide pest of stored grain that mainly damages flour, and not only causes serious loss of flour quality but also leads to deterioration of flour quality. Chemical detection plays a key role in insect behavior, and the role of odorant-binding proteins (OBPs) in insect chemical detection has been widely studied. OBPs can interact with small molecule compounds and thereby modulate variation in insecticide susceptibility in insects. In this study, a total of 65 small molecule compounds are selected to investigate the bound effect with TcOBP C12. The molecular docking results showed that ß-caryophyllene, (-)-catechin, butylated hydroxytoluene, diphenyl phthalate and quercetin were the top five compounds, with docking binding energies of -6.11, -5.25, -5.09, -5.05, and - 5.03 Kcal/mol, respectively. Molecular dynamics analysis indicated that odorant binding protein C12 (TcOBP C12) exhibited high binding affinity to all five tested chemical ligands, evidenced by fluorescence quenching assay in vitro. In addition, the contact toxicity assay results suggested that these chemical agents caused a dose-dependent increase in mortality rate for T. castaneum adults. The TcOBP C12 gene was upregulated >2 times after a 24-h exposure, indicating that OBP C12 may play an important role for T. castaneum in response to these chemical agents. In conclusion, our results provide a theoretical basis for future insecticide experiments and pest management.

Phytochemical Characterization, Fumigant And Contact Toxicity Activities Of Four Essential Oils Against Eriophyid Gall Mite, Aceria pongamiae Keifer (Acarina: Eriophyidae).

Plant-derived essential oils (EO) offer natural alternative to chemical pesticides for eco-friendly pest control approaches. Aceria pongamiae Keifer, a notorious pest that affects Pongamia pinnata (L.) Pierre has mainly been controlled using synthetic acaricides leading to resistance development and environmental issues. EOs provide natural biodegradable option for pest control with unique mode of action. Study evaluates acaricidal efficacy of EOs-eucalyptus Eucalyptus maculata Hook (EEO), lavender Lavandula angustifola L. (LEO), peppermint Mentha piperita L. (PEO) and black pepper Piper nigrum L. (BPEO) against A. pongamiae for the first time. Biological activity of EOs using fumigation and contact toxicity assays at concentrations ranging from 0.1 to 1% and 0.6 to 0.9% respectively, overexposure periods of 24, 48 and 72h was investigated. Chemical characterization was performed using GC-MS analysis. Eucalyptol (62.88%), linalyl acetate (39.11%), menthol (44.35%) and caryophyllene (32.77%) were the main components of EEO, LEO, PEO and BPEO respectively. After 24h observation, EEO (LC50=1.01%) and after 48 and 72h, PEO had the highest fumigant toxicity (LC50=0.71 and 0.29% respectively). The BPEO showed the most contact toxicity after 24, 48 and 72h (LC50=0.92, 0.68 and 0.46% respectively). This work reinforces the selection of adequate essential oils for implementation in future pest control strategies.

Contact Toxicity and Repellent Effects of Essential Oils from Toddalia asiatica against Two Stored-Product Insects.

Insect infestations continually endanger stored goods, underscoring the significance of discovering eco-friendly insecticides for pest management. Essential oils (EOs) from different parts of Toddalia asiatica (leaf, fruit and branch) were extracted by hydrodistillation and analyzed by GC-MS. Carvene, p-cymene and muurolene are the principal compounds of T. asiatica leaf (TAL), T. asiatica fruit (TAF) and T. asiatica branch (TAB) EO respectively. Our work aimed to assess the contact toxicity and repellent effects of EOs on two storage pests, Tribolium castaneum and Lasioderma serricorne. All tested EOs exhibited obvious contact toxicity, especially, TAL EO against T. castaneum (33.48 µg/adult) and TAF EO against L. serricorne (16.42 µg/adult). Repellency tests revealed that TAL and TAF EOs, at a concentration of 78.63 nL/cm2, achieved nearing 100% efficiency against T. castaneum. These results suggest that EOs of T. asiatica could be used as effective botanical insecticides for managing stored-product insects.

Extraction, Chemical Composition and Insecticidal Activities of Lantana camara Linn. Leaf Essential Oils against Tribolium castaneum, Lasioderma serricorne and Callosobruchus chinensis.

Storage pests and the food spoilage they cause are problems of great concern. Using essential oil obtained from different plants as an insecticide against these storage pests can be considered an environmentally friendly pest management option. Lantana camara Linn. (family Verbenaceae) is a flowering species, and is also a noxious weed that can proliferate well in nearly all geographical habitats. A biopesticide derived from the essential oil extracted from this plant can offer an effective solution for controlling storage pests. The goal of this study is to extract and analyse the chemical composition of essential oil obtained from L. camara leaves, and assess its effectiveness as a bioactive substance against three storage pests: Tribolium castaneum, Lasioderma serricorne, and Callosobruchus chinensis. The yield of essential oil extracted from L. camara leaves was about 0.24 ± 0.014%. By employing the GC-MS technique, the major phytochemicals contained in L. camara leaf essential oil were identified as caryophyllene (69.96%), isoledene (12%), and ɑ-copaene (4.11%). The essential oil exhibited excellent fumigant toxicity (LC50 of 16.70 mg/L air for T. castaneum, 4.141 mg/L air for L. serricorne and 6.245 mg/L air for C. chinensis at 24 h), contact toxicity (LC50 of 8.93 mg/cm2 for T. castaneum, 4.82 mg/cm2 for L. serricorne and 6.24 mg/cm2 for C. chinensis after 24 h) along with effective repellent activity towards the test insects. In addition, the oil showed no significant phytotoxicity on the germination of paddy seeds. This presents the potential to utilize a weed in developing a biopesticide for effectively managing stored product insects because of its strong bioactivity.

Antioxidant, insecticidal, antifeedant, and repellent activities of oregano (Origanum vulgare).

This study aimed to assess the antioxidant capacity, the insecticidal, feeding deterrence, repellent effects against Tribolium confusum of the essential oil (EO) and the organic extracts (ME) of Origanum vulgare. The chemical composition of the EO revealed the presence thirty-nine components dominated by carvacrol (81%). With respect to the EO, the ME acted as a potent free radical scavenger with IC50 values of 0.127 and 0.058 mg/mL, respectively. The EO exhibited the most significant toxicity compared to the ME with a mortality of 62 and 20% at 0.08 µL/insect after 24h whereas the EO expressed the highest repellency compared to the ME with a PR of 70 and 38% after 24h. As for feeding deterrence, both samples influenced all nutritional indexes. The findings found in this work might help in the promotion of oregano as natural antioxidant, antifeedant, repellent and insecticide as an alternative to conventional harmful ones.

Assessment of Contact Toxicity and Repellent Effects of Essential Oils from Piper Plants Piper yunnanense and Piper boehmeriifolium against Three Stored-Product Insects.

Storage is a crucial part during grain production for the massive spoilage caused by stored product insects. Essential oils (EOs) of plant origin have been highly recommended to combating insects which are biodegradable and safe mode of action. Hence, to make the fullest use of natural resources, essential oils of different parts from Piper yunnanense (the whole part, PYW; fruits, PYF; leaves, PYL) and Piper boehmeriifolium (leaves, PBL) were extracted by steam distillation method in the present study. Gas chromatography-mass spectrometry (GC-MS) characterization revealed bicyclogermacrene (PYW), γ-muurolene (PYF), δ-cadinene (PYL) and methyl 4,7,10,13,16,19-docosahexaenoate (PBL) as the principal compound of each essential oil. Sesquiterpene hydrocarbons were also recognized as the richest class accounting for 56.3 %-94.9 % of the total oil. Three storage pests, Tribolium castaneum, Lasioderma serricorne and Liposceis bostrychophila, were exposed to different concentrations of EOs to determine their insecticidal effects. All tested samples performed modest contact toxicity in contrast to a bioactive ingredient pyrethrin, among which the most substantial effects were observed in PYF EOs against T. castaneum (35.84 µg/adult), PBL EOs against L. serricorne (15.76 µg/adult) and PYW EOs against L. bostrychophila (57.70 µg/cm2 ). In terms of repellency tests, essential oils of PYF at 78.63 nL/cm2 demonstrated to have a remarkable repellence against T. castaneum at 2h and 4h post-exposure. The investigations indicate diverse variations in the chemical profiles and insecticidal efficacies of P. yunnanense and P. boehmeriifolium EOs, providing more experimental evidence for the use of the Piper plants.

Acaricidal activities of paeonol from Moutan Cortex, dried bark of Paeonia × suffruticosa, against the grain pest mite Aleuroglyphus ovatus (Acari: Acaridae).

Aleuroglyphus ovatus (Acari: Acaridae) is a major pest mite of stored grains that is distributed worldwide. Paeonol, a phenolic component of the essential oil extracted from the Chinese herb Paeonia moutan, possesses a range of biological activities, including antiviral, antifungal and acaricidal activity. This study investigated the bioactivity of paeonol against A. ovatus and its effect on the activity of detoxification enzymes. The bioactivity of paeonol against A. ovatus was determined by contact, fumigation and repellency bioassays, and the mechanism was preliminarily explored via morphological observation of the color changes of mite epidermis and determination of the changing trend of some important enzymes associated with acaricidal efficacy in the mites. The results showed that the median lethal concentration (LC50) in the contact and fumigation bioassays was 9.832 µg/cm2 and 14.827 µg/cm3, respectively, and the acaricidal activity of paeonol was higher under direct contact than under fumigation. Dynamic symptomatology studies registered typical neurotoxicity symptoms including excitation, convulsion and paralysis in A. ovatus treated with paeonol. The enzyme activity of catalase (CAT), nitric oxide synthase (NOS) and glutathione-S-transferase (GST) was higher, whereas the activity of superoxide dismutase (SOD) and acetylcholinesterase (AChE) was lower, compared to the control group. CAT, NOS and GST were activated, whereas SOD and AChE activities were inhibited after paeonol intervention. Our findings suggest paeonol has potent acaricidal activity against A. ovatus and thus may be used as an agent to control the stored-product mite A. ovatus.

Biological activities and gene expression of detoxifying enzymes in Tribolium castaneum induced by Moutan cortex essential oil.

Tribolium castaneum is one of the most harmful storage pests in the world. The aim of this study was to determine the chemical composition, repellent, and contact activities of Moutan cortex essential oil against this insect pest. In addition, the effects of Moutan cortex were examined on the expressions of three major detoxifying enzyme genes in T. castaneum. Four components were identified in this essential oil by gas chromatography-mass spectrometry (GC-MS), which was predominantly paeonol (99.13%). Paeonol exerted significant repellent activity against T. castaneum, which was more potent than the positive control N.N-diethyl-meta-toluamide (DEET). The most significant contact toxicity was observed at 24 h after exposure to paeonol. Further, quantitative real-time PCR (qRT-PCR) was used to assess expression changes in three detoxification enzyme genes in T. castaneum, including carboxylesterase (CarE), glutathione S-transferase (Gst) and cytochrome P4506BQ8 (Cyp6bq8). Among these, Gst was most highly up-regulated after treatment with paeonol with the highest expression level of 4.9-fold (Rps18 as internal reference gene) greater than control at 24 h following treatment. Data indicated that Gst might play a critical role in metabolic detoxification of toxic xenobiotics. Taken together, our findings might lay a foundation for development of paeonol as a potential natural repellent or pesticide to control storage pests.

A direct contact bioassay using immobilized microalgal balls to evaluate the toxicity of contaminated field soils.

The present study used a bioassay of immobilized microalgae (Chlorella vulgaris) via direct contact to assess the toxicity of eleven uncontaminated (reference) and five field contaminated soils with various physicochemical properties and contamination. Photosynthetic oxygen concentration in the headspace of the test kit by Chlorella vulgaris in the reference soils ranged between 12.93% and 14.80% and only 2.54%-7.14% in the contaminated soils, respectively. Inherent test variability (CVi) values ranged between 2.90% and 9.04%; variation due to soil natural properties (CVrs) ranged between 0.33% and 13.0%; and minimal detectable difference (MDD) values ranged from 4.69% to 11.6%. A computed toxicity threshold of 15% was established for microalgae soil toxicity tests based on calculations of the maximal tolerable inhibition (MTI). All contaminated soils were considered toxic to microalgae because their levels of inhibition ranged between 39.5% and 82.9%, exceeding the 15% toxicity threshold. It can be concluded that the elevated concentrations of heavy metals and organic contaminants in the contaminated soils induced the higher inhibitory levels. Overall, direct contact soil toxicity tests using immobilized microalgae provided coherent and repeatable data and can be utilized as a simple and suitable tool for the toxicity testing of contaminated field soils.

Synthesis and Insecticidal Activity of Fire Ant Venom Alkaloid-Based 2-Methyl-6-alkyl-Δ1,6-piperideines.

2,6-dialkylpiperideines found in the venom of Solenopsis (Hymenoptera, Formicidae) fire ants are a range of compounds possessing various biological activities. A series of racemic 2-methyl-6-alkyl-Δ1,6-piperideines were synthesized for chemical confirmation of the natural products found in fire ant venom, and the evaluation of their biological activity. Synthetic Δ1,6-piperideines and the natural compounds in the cis-alkaloid fraction of Solenopsis invicta had identical mass spectra and retention times. Their insecticidal activities against the third-instar larvae of cotton bollworm (Helicoverpa armigera) were evaluated by using injection and topical application methods. All three compounds exhibited no lethal effect at concentrations of 0.05-0.4 mol/L by topical treatment, but moderate lethal effect at 0.4 mol/L through injection treatment. Compound 6a showed significantly higher activity than the natural insecticide nicotine. The differences in activity among compounds 6b, 6c and nicotine were not significant. The elongation of the carbon chain at the 6-position of the piperideine ring appears to decrease insecticidal activity.

Insecticidal and Repellent Activity of Thymus quinquecostatus Celak. Essential Oil and Major Compositions against Three Stored-Product Insects.

Thymus quinquecostatus Celak. of the Lamiaceae family has a long history of dual use of medicine and food with high economic value, and has been proved to have good antioxidative, antimicrobial, and antidiabetic activities. Essential oil (EO) extracted from the aerial part of T. quinquecostatus was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC/MS) and GC. Totally 45 compounds were identified accounting for 98.5 % of the EO. The major constituents of the EO were linalool (52.003 %), borneol (10.911 %) and anethole (5.325 %). Fumigant, contact and repellent activity of T. quinquecostatus essential oil (EO) against Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma Serricorne (Coleoptera: Anobiidae), Liposcelis bostrychophila (Psocoptera: Liposcelididae) were evaluated in this work. T. quinquecostatus EO and three major constituents showed varying degrees of insecticidal and repellent activities to three stored-product insects. Anethole stated the best fumigant and contact activity than others did to all three insect species. EO and compounds showed general repellent activity against three target insects. This work suggests that the EO of T. quinquecostatus has promising potential to be developed into botanical pesticides and repellents controlling pest damage in warehouses and grain stores.

Phytochemistry and insecticidal activity of Annona mucosa leaf extracts against Sitophilus zeamais and Prostephanus truncatus.

A new oleanane type triterpene characterized as 3α, 24-diacetoxy-12-oleanene (1) together with known compounds 2-10, were isolated from Annona mucosa leaf extracts. Their structural elucidation was accomplished using physical and spectroscopic methods. The compounds showed weak to moderate insecticidal activities against stored maize insect pests Sitophilus zeamais and Prostephanus truncatus.[Formula: see text].

Bioactivity and efficacy of essential oils extracted from Artemisia annua against Tribolium casteneum (Herbst. 1797) (Coleoptera: Tenebrionidae): An eco-friendly approach.

Tribolium casteneum is a major stored grains pest causing huge loss by secreting toxic quinones' which make the grains unfit for human consumption. Increasing concern about the fast-growing resistance in T. casteneum against fumigants has evoked more intense research worldwide. Therefore, finding an eco-friendly alternative for the management of the pest is of great importance. In this study, the insecticidal activity of the essential oils (EOs) of Artemisia annua is evaluated. Chemical composition of the EOs eluted with methanol and petroleum ether was analysed through Gas chromatography-mass spectrometry (GC-MS). The result has reported a total of 13 & 16 compounds in the methanol and petroleum ether EOs respectively. In contact toxicity studies, adults were found more susceptible to the petroleum ether EOs (LD50 = 0.43 mg adult-1) than the methanolic EOs (LD50 = 1.87 mg adult-1). Petroleum ether EOs was also superior in fumigant assays against both the adults (0.81 mg L air-1) and larvae (0.65 mg L air-1). Moreover, the same was also recorded as a strong repellent. The bio-molecular studies conducted to gain an insight into the extent of metabolic disturbances inflicted in the treatment sets has shown a significant increase in Lipid peroxidase and decrease (p˂0.01) in protein, Acetylcholinesterase, Glutathione S Transferees, Reduced Glutathione level. This indicates the major signs of oxidative stress in the treatment sets. The Results ascertain the knowledge to develop natural insecticides from Artemisia annua using a potential solvent to be used in the future as an efficient management tool against T. casteneum.

Insecticidal Toxicities of Three Main Constituents Derived from Trachyspermum ammi (L.) Sprague ex Turrill Fruits against the Small Hive Beetles, Aethina tumida Murray.

Small hive beetle (Aethina tumida Murray), indigenous to Africa, has spread to other parts of the world where has become a threat to the honeybee industry. In the present study, insecticidal properties (contact, fumigant, and repellent toxicities) of three main constituents derived from Trachyspermum ammi (L.) Sprague ex Turrill fruits essential oil were evaluated against adult small hive beetles under laboratory conditions. The Hydrodistillation of T. ammi fruits, grown in Ethiopia, yielded a pale yellow essential oil (3.5% v/w) with a strong aromatic odor. Analyses by gas chromatography-mass spectrometry identified twenty-two compounds that accounted for 98.68% of the total essential oil. The essential oil was dominated by monoterpenoids, comprising -terpinene (32.72%), p-cymene (27.92%), and thymol (24.36%). The essential oil showed strong contact and fumigation toxicities against the small hive beetle adults, with a LD50 value of 66.64 µg/adult and a LC50 value of 89.03 mg/L air, respectively. Among the main constituents, thymol was the most toxic component found in both contact (LD50 = 41.79 µg/adult) and fumigation (LC50 = 52.66 mg/L air) toxicities. The other two components, -terpinene and p-cymene, were less effective in both contact and fumigant toxicities testing. The results showed that T. ammi essential oil and thymol could serve as potential alternatives to synthetic insecticides for the control of small hive beetle adults.

Insecticidal Activity and Insecticidal Mechanism of Total Saponins from Camellia oleifera.

Chemical pesticides are commonly used during the cultivation of agricultural products to control pests and diseases. Excessive use of traditional pesticides can cause environmental and human health risks. There are ongoing searches for new plant-derived pesticides to reduce the use of chemical pesticides. In this study, tea saponin extracts of different purities were extracted from Camellia oleifera seeds using AB-8 macroporous resin and gradient elution with ethanol. The insecticidal effects of the tea saponin extracts were evaluated by contact toxicity tests and stomach toxicity tests using the lepidopteran pest of tea plantation, Ectropis obliqua. The total saponins extracted using 70% ethanol showed strong contact toxicity (LC50 = 8.459 mg/L) and stomach toxicity (LC50 = 22.395 mg/L). In-depth mechanistic studies demonstrated that tea saponins can disrupt the waxy layer of the epidermis, causing serious loss of water, and can penetrate the inside of the intestine of E. obliqua. After consumption of the tea saponins, the intestinal villi were shortened and the cavities of the intestinal wall were disrupted, which resulted in larval death. This study highlights the potential of tea saponins as a natural, plant-derived pesticide for the management of plant pests.

Efficacy of Origanum syriacum Essential Oil against the Mosquito Vector Culex quinquefasciatus and the Gastrointestinal Parasite Anisakis simplex, with Insights on Acetylcholinesterase Inhibition.

Developing effective and eco-friendly antiparasitic drugs and insecticides is an issue of high importance nowadays. In this study, we evaluated the anthelminthic and insecticidal potential of the leaf essential oil obtained from Origanum syriacum against the L3 larvae of the parasitic nematode Anisakis simplex and larvae and adults of the mosquito Culex quinquefasciatus. Tests on A. simplex were performed by standard larvicidal and penetration assays, while mosquito toxicity was assessed relying on larvicidal, tarsal contact, and fumigation tests. To shed light on the possible mode of action, we analyzed the oil impact as acetylcholinesterase (AChE) inhibitor. This oil was particularly active on L3 larvae of A. simplex, showing a LC50 of 0.087 and 0.067 mg mL-1 after 24 and 48 h treatment, respectively. O. syriacum essential oil was highly effective on both larvae and adults of C. quinquefasciatus, showing LC50 values of 32.4 mg L-1 and 28.1 µg cm-2, respectively. Its main constituent, carvacrol, achieved larvicidal LC50(90) of 29.5 and 39.2 mg L-1, while contact toxicity assays on adults had an LC50(90) of 25.5 and 35.8 µg cm-2, respectively. In fumigation assays, the LC50 was 12.1 µL L-1 after 1 h and decreased to 1.3 µL L-1 in 24 h of exposure. Similarly, the fumigation LC50 of carvacrol was 8.2 µL L-1 after 1 h of exposure, strongly decreasing to 0.8 µL L-1 after 24 h of exposure. These results support the folk usage of Lebanese oregano as an antiparasitic agent, providing new insights about its utilization for developing new effective and eco-friendly nematocidal and insecticidal products.

Toxicity and repellency of essential oil from Evodia lenticellata Huang fruits and its major monoterpenes against three stored-product insects.

In this work, the essential oil (EO) was extracted from the fruits of Evodia lenticellata, and the fumigant toxicity, contact toxicity and repellency against three stored-product insect species were evaluated for the obtained EO and several of its chemical components. The target insects were the adults of Tribolium castaneum (Coleoptera: Tenebrionidae), Lasioderma serricorne (Coleoptera: Anobiidae) and Liposcelis bostrychophila (Psocoptera: Liposcelididae). The EO was obtained with hydrodistillation and its chemical components were analyzed with the gas chromatography-mass spectrometry (GC-MS). Twenty-seven compounds, accounting for 83.1% of the total amount of the oil, were identified from the EO sample. The main compounds included linalool (12.0%), ß-pinene (11.5%), 3-carene (9.6%), caryophyllene oxide (8.7%) and ß-caryophyllene (7.9%). Among them, the amounts of monoterpenes and sesquiterpenes were as high as 52.7% and 22.7% to the total amount of EO respectively. The results of bioactivity test showed that the EO and its testing compounds had interspecific toxicity and repellent activity. So that, it might be expected that the EO extracted from the fruits of E. lenticellata could be developed to a new type of eco-friendly natural insecticide or repellent for the control of stored-product insects.

Efficacy of Compounds Isolated from the Essential Oil of Artemisia lavandulaefolia in Control of the Cigarette Beetle, Lasioderma serricorne.

To develop natural product resources to control cigarette beetles (Lasioderma serricorne), the essential oil from Artemisia lavandulaefolia (Compositae) was investigated. Oil was extracted by hydrodistillation of the above-ground portion of A. lavandulaefolia and analyzed using gas chromatography-mass spectrometer (GC-MS). Extracted essential oil and three compounds isolated from the oil were then evaluated in laboratory assays to determine the fumigant, contact, and repellent efficacy against the stored-products' pest, L. serricorne. The bioactive constituents from the oil extracts were identified as chamazulene (40.4%), 1,8-cineole (16.0%), and ß-caryophyllene (11.5%). In the insecticidal activity assay, the adults of L. serricorne were susceptible to fumigant action of the essential oil and 1,8-cineole, with LC50 values of 31.81 and 5.18 mg/L air. The essential oil, 1,8-cineole, chamazulene, and ß-caryophyllene exhibited contact toxicity with LD50 values of 13.51, 15.58, 15.18 and 35.52 µg/adult, respectively. During the repellency test, the essential oil and chamazulene had repellency approximating the positive control. The results indicated that chamazulene was abundant in A. lavandulaefolia essential oil and was toxic to cigarette beetles.

Identification of Insecticidal Constituents from the Essential Oil from the Aerial Parts Stachys riederi var. japonica.

The essential oil of Stachys riederi var. japonica (Family: Lamiaceae) was extracted by hydrodistillation and determined by GC and GC-MS. A total of 40 components were identified, representing 96.01% of the total oil composition. The major compounds in the essential oil were acetanisole (15.43%), anisole (9.43%), 1,8-cineole (8.07%), geraniol (7.89%), eugenol (4.54%), caryophyllene oxide (4.47%), caryophyllene (4.21%) and linalool (4.07%). Five active constituents (acetanisole, anisole, 1,8-cineole, eugenol and geraniol) were identified by bioactivity-directed fractionation. The essential oil possessed fumigant toxicity against maize weevils (Sitophilus zeamais) and booklice (Liposcelis bostrychophila), with LC50 values of 15.0 mg/L and 0.7 mg/L, respectively. Eugenol and anisole exhibited stronger fumigant toxicity than the oil against booklice. 1,8-Cineole showed stronger toxicity, and anisole as well as eugenol exhibited the same level of fumigant toxicity as the essential oil against maize weevils. The essential oil also exhibited contact toxicity against S. zeamais adults and L. bostrychophila, with LC50 values of 21.8 µg/adult and 287.0 µg/cm², respectively. The results indicated that the essential oil of S. riederi var. japonica and its isolates show potential as fumigants, and for their contact toxicity against grain storage insects.