Search

Rhyzopertha dominica and Tribolium castaneum are two significant insect pests that affect the quality, quantity, and commercial value of stored products. The aim of this study was to assess the chemical composition, repellency, and insecticidal activity of Pinus halepensis leaf EO on adults of Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). The EO of P. halepensis Mill. was extracted using hydrodistillation and analyzed for its chemical composition by GC-MS. The major components identified were 1-nonadecene (25.51%), 1-hexadecene (20.79%), pimaric acid (16.71%), and palmitic acid (12.47%). The repellency test was determined by the area-preference method. P. halepensis EO exhibited significant repellent activity against T. castaneum and R. dominica. It showed high class IV repulsion rates, reaching 63.60% against T. castaneum and 66.50% against R. dominica. The repellent effect was most potent at the highest concentration tested (16 µL/mL), achieving a 100% efficacy against T. castaneum after 4 h and after 3 h against R. dominica. The contact toxicity test was carried out by impregnating filter paper disks with increasing doses of the EO studied. P. halepensis EO was the most toxic against R. dominica (LC50 = 17.11 µL/mL, LC90 = 30.02 µL/mL) and T. castaneum (LC50 = 20.92 µL/mL, LC90 = 32.18 µL/mL) after 96 h of exposure. The ability of P. halepensis EO to repel and eliminate insects suggests that it could be used as a new treatment to prevent insect infestations of R. dominica and T. castaneum. [ABSTRACT FROM AUTHOR]

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a major pest of various plants with a worldwide distribution. Extensive use of chemical pesticides has led to the development of resistance in this pest, making biological control agents a viable alternative for its management. The predatory mites, Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias–Henriot (Acari: Phytoseiidae) are the most important predators of the two-spotted spider mites. In this study, the toxicity of two acaricides chlorfenapyr and acequinocyl, on these predators was evaluated, and the walking behavior of predatory mites after exposure to residues of the pesticides was assessed using a video tracking system. Based on the results, the LC50 values of both acaricides was estimated to be higher than their field concentration, and chlorfenapyr was found to be five-fold more toxic than acequinocyl. In the behavioral assay, both acaricides significantly affected the distance and speed of walking, resting time, and frequency of stops of both predatory mites. In the escape assay, both compounds had an irritable effect on both predatory mites, as the mites avoided areas contaminated with pesticide residues and their presence in the untreated area was significantly longer than in the treated area (P < 0.05). However, the study found no correlation between toxicity and irritability. According to the results of this study, N. californicus and P. persimilis possess the ability to detect the presence of pesticide residues in their environment and try to avoid them. Moreover, both compounds are at low risk to these mites, but acequinocyl is much safer and is a suitable option for use in integrated pest management. [ABSTRACT FROM AUTHOR]

Various pure monoterpenes and essential oils, including limonene-free citrus oil (LFC), ocimene, dihydrotagetone, carvone, α-terpineol, terpenyl acetate, and linalool were tested for their toxicity and repellency against Sitophilus oryzae (rice weevil) and Lipaphis erysimi (mustard aphid). All the compounds showed varying degrees of toxicity on both the insect pests. LFC exhibited the highest repellent activity against L. erysimi (93.33%), followed by carvone (76.66%) and α-terpenyl acetate (73.33%). LFC and carvone also caused 100% aphid mortality within 12 h, with similar efficacy of linalool (90.0%) and α-terpenyl acetate (90.0%). For S. oryzae, ocimene, linalool, and dihydrotagetone produced 100% mortality after 15 days of the treatment of the stored grains. It is the first study to examine the toxicological effects of isolated pure monoterpenes, ocimene, dihydrotagetone, and a fraction of citrus oil LFC on rice weevils and mustard aphids. The strong effectiveness of LFC indicated that the insecticidal activity of citrus oil is not solely attributed to its main component, limonene; the minor compounds also play a crucial role in its insecticidal properties. [ABSTRACT FROM AUTHOR]

Abstract well known for its insecticidal, anti-inflammatory, antioxidant, anticancer, anti-rheumatic and antibiotic properties, Turmeric (Curcuma longa L.) Essential oil (EO), is effective in repelling and controlling many different pest species. The present study evaluates in vitro efficacy of turmeric EO against ectoparasitic tick, Rhipicephalus (Boophilus)annulatus collected from their natural host, domesticated cows. Repellency and toxicity of the EO on ectoparasitic ticks was analyzed with petri dish choice bioassay and AIT (Adult immersion test) against adult engorged females and nymphal stages of ticks. The Repellency Concentration (RC50) and Lethal Concentration (LC50) reproductive index, inhibition of oviposition and egg hatchability of treated ticks were estimated. GC-MS analysis identified Ar-turmerone as the major phytochemical, which induces adulticidal and repellant properties of EO. The nymphal stages of the ticks exhibited greater repellency on application of EO than the adult stage. Also, EO induced effective mortality in adult ticks. Further, this lethal concentration is capable of producing a decreased output in reproductive parameters namely, fecundity, % of oviposition and egg hatchability in surviving ticks thereby considerably reducing Rhipicephalus (Boophilus) R(B). annulatus population on its host. This study reveals the potency C. longa EO to be used as an effective pest control agent against R (B). annulatus infestation that can serve as an alternative to synthetic pesticides.

Citronella (Cymbopogon nardus) produces essential oil and has the potential to be developed as a botanical insecticide. However, in its development, botanical insecticides encountered several obstacles. Utilizing nanotechnology in nanoemulsion preparations is one method to overcome these challenges. This research aimed to determine the contents of the citronella oil nanoemulsion (CiONano) and citronella oil non-nano emulsion (CiONonNano) formulations and evaluate the toxicity, repellency, and prevention of oviposition against female adults of Callosobruchus maculatus. This was the first work to evaluate the nanoemulsion of citronella oil prepared from spontaneous emulsification against C. maculatus. Chemical content testing used the GCMS method. A toxicity test using the contact method (LC50), used a probit program, while testing for repellency and oviposition deterrence was carried out using the no-choice method. The highest chemical component of CiONonNano and CiONano was citronella (37.56 and 38.97%, respectively), followed by citronellol (17.71 and 18.99%, consecutively) and geraniol (14.78 and 15.38%, respectively). In general, the CiONano formulation showed higher repellency and toxicity than CiONonNano. The LC50 values of CiONano were 10.03%. These values were 4.49 times lower than the LC50 of CiONonNano. However, the results of the oviposition inhibition test showed different results, the CiONonNano formulation had a higher oviposition inhibition capacity for adult female C. maculatus than CiONano. As a result, it is necessary to optimize the CiONano formulation to obtain consistent results in controlling C. maculatus.

Background & objectives: At present, use of synthetic pesticides to manage insects and other arthropods creates a number of issues that are related to the environment and public health. The goal of the present study is to find repellent activity of Vitex negundo and Curcuma longa herbal extracts against the wild species Simulium (blackfly) bite. Methods: We have studied Simulium biting behavior and tested the repellency of herbal extract obtained from Vitex negundo L. (Lamiales: Lamiaceae) and Curcuma longa L. (Zingiberal: Zingiberaceae) along with their essential oils in three locations in Arunachal Pradesh, India on human volunteers’ resistance to Simulium (blackflies). The reported herbal extracts were incorporated to topical drug delivery vehicle as a cream and gel. Results: The methanolic extract of Vitex negundo cream and gel formulation showed >2 h safety at 5% concentration and >5 h safety at 10% concentration in all the testing sites followed by ethyl acetate extract. Whereas, chloroform extract of Curcuma longa cream and gel formulation provided >1 h safety at 5% concentration and >4 h safety at 10% concentration. Interpretation & conclusion: At an optimum concentration of 10%, the methanolic extract of Vitex negundo cream provided complete protection times (CPTs) 320.4, 358.6, and 346.4 min, respectively. These findings offer confirmation of the methanolic extract and chloroform extract potential for use in new blackfly repellents.

Piper crassinervium Kunth (Piperaceae) essential oil (EO) was evaluated for its toxicity and repellency against red imported fire ants (RIFA), Solenopsis invicta Buren, and a hybrid (HIFA) of red (S. invicta) and black (S. richteri Forel) imported fire ants. Through bioactivity-guided fractionation, two major components, elemicin and myristicin, were isolated from the EO. Removal of treated sand in a digging bioassay was used as the criterion for repellency. The EO showed significantly higher repellency at concentrations of 7.8 µg/g against RIFA and HIFA workers, as compared to the DEET (N,N-diethyl-meta-toluamide) or ethanol control. Elemicin exhibited repellency at 3.9 and 7.8 µg/g against RIFA and HIFA workers, respectively, whereas myristicin was active at 7.8 µg/g against both species. DEET failed at 31.25 µg/g against RIFA and 15.6 µg/g against HIFA. The EO showed LC50 values of 97.9 and 73.7 µg/g against RIFA and HIFA workers, respectively. Myristicin was more toxic against RIFA and HIFA with LC50 values of 54.3 and 35.3 µg/g, respectively. Elemicin showed 20–40% mortality at the highest screening dose of 125 µg/g. Fipronil exhibited the highest toxicity against RIFA and HIFA, with LC50 of 0.43 and 0.51 µg/g, respectively. Different formulations of these natural products should be evaluated to explore their use potential under natural field conditions. [ABSTRACT FROM AUTHOR]

well known for its insecticidal, anti-inflammatory, antioxidant, anticancer, anti-rheumatic and antibiotic properties, Turmeric (Curcuma longa L.) Essential oil (EO), is effective in repelling and controlling many different pest species. The present study evaluates in vitro efficacy of turmeric EO against ectoparasitic tick, Rhipicephalus (Boophilus)annulatus collected from their natural host, domesticated cows. Repellency and toxicity of the EO on ectoparasitic ticks was analyzed with petri dish choice bioassay and AIT (Adult immersion test) against adult engorged females and nymphal stages of ticks. The Repellency Concentration (RC50) and Lethal Concentration (LC50) reproductive index, inhibition of oviposition and egg hatchability of treated ticks were estimated. GC-MS analysis identified Ar-turmerone as the major phytochemical, which induces adulticidal and repellant properties of EO. The nymphal stages of the ticks exhibited greater repellency on application of EO than the adult stage. Also, EO induced effective mortality in adult ticks. Further, this lethal concentration is capable of producing a decreased output in reproductive parameters namely, fecundity, % of oviposition and egg hatchability in surviving ticks thereby considerably reducing Rhipicephalus (Boophilus) R(B). annulatus population on its host. This study reveals the potency C. longa EO to be used as an effective pest control agent against R (B). annulatus infestation that can serve as an alternative to synthetic pesticides. [ABSTRACT FROM AUTHOR]

The insecticidal and repellent activities of the four wild plant extracts: stinging nettle, Urtica dioica L., white henbane, Hyoscyamus albus L., camphorweeds, Pluchea dioscoridis L., and cocklebur, Xanthium strumarium L. were tested compared to the insecticide spirotetramat against the 3rd nymphal instar of Aphis gossypii Glover and adult females of Phenacoccus solenopsis Tinsley after 24 and 48 h of treatment. Their effects on acetylcholinesterase (AChE) and glutathione-S-transferase (GST) enzyme activities were also assessed to explore their possible mechanisms of action. The phenolic compounds of the plant extracts were investigated by high-performance liquid chromatography (HPLC) analysis. The most abundant compounds in the methanol extract from P. dioscoridis were gallic acid (14.45 µg/mL), and cinnamic acid (11.44 µg/mL); from U. dioica were caffeic acid (15.32 µg/mL) and syringic acid (13.47 µg/mL); from H. albus were syringic acid (7.12 µg/mL) and catechol (5.33 µg/mL); and from X. strumarium were p-coumaric acid (24.53 µg/mL) and pyrogallol (18.35 µg/mL). According to the LC50 values, the contact toxicity of U. dioica, H. albus, P. dioscoridis, and X. strumarium against A. gossypii was 40.3, 60.6, 56.2, and 32.3 mg/L, whereas, the contact toxicity against P. solenopsis was 56.4, 67.5, 64.3, and 36.2 mg/L, compared to the spirotetramat (17.2 and 24.5 mg/L), respectively, at 48 h of treatment. The highest repellency rates were observed with LC50 values for X. strumarium (63.2 and 60.3%), followed by U. dioica (46.2 and 43.5%), P. dioscoridis (45.3 and 42.8%), and H. albus extract (38.8 and 35.2%) compared to the spirotetramat (78.5 and 76.2%) against A. gossypii and P. solenopsis at 24 h, but decreased with time. The AChE and GST activities in pests were significantly inhibited, compared to control and spirotetramat, with dose and time-dependent effects. These findings indicate that tested wild extracts may be suggested as viable alternatives for aphids and mealybugs control. [ABSTRACT FROM AUTHOR]

Simple Summary: We tested (E/Z)-3-butylidenephthalide, a natural compound that was isolated from the ethanolic extract of Ligusticum porteri roots, for repellency and toxicity against workers of imported fire ants. In our digging bioassays, workers removed significantly less amount of sand from vials containing sand treated with (E/Z)-3-butylidenephthalide when compared to the ethanol control. Based on sand removal, red imported fire ant workers showed a digging suppression up to the lowest concentration of 0.6 µg/g in (E/Z)-3-butylidenephthalide as compared to the control solvent. Black imported fire ants showed repellency at the lowest concentration of 0.15 µg/g whereas hybrid imported fire ants showed repellency at the lowest concentration of 4.9 µg/g. In red and black imported fire ants, DEET was active up to the concentration of 62.5 µg/g, whereas the treatment failed at 15.6 µg/g in hybrid fire ants. (E/Z)-3-butylidenephthalide showed LC50 values of 11 and 16.4 µg/g against red and black imported fire ants, respectively, followed by an LC50 of 104.7 µg/g in hybrid fire ants. Fipronil with LC50 values of 0.49, 0.33, and 0.53 µg/g against red, black, and hybrid fire ants, respectively, proved to be more toxic. This study provides valuable biological information on this natural product against imported fire ants, emphasizing further testing under natural field conditions. Imported fire ants are pests of significant importance, especially in the southern United States. We tested (E/Z)-3-butylidenephthalide, a natural compound that was isolated from the ethanolic extract of Ligusticum porteri roots, as a repellent and toxicant against workers of imported fire ants. A series of serial concentrations, starting from 156 µg/g until failure, were tested using digging bioassays. Workers removed significantly less sand from the vials treated with (E/Z)-3-butylidenephthalide as compared to the ethanol control. Based on sand removal data, (E/Z)-3-butylidenephthalide treatment resulted in a more significant digging suppression against red imported fire ant workers at concentrations ranging between 19.5 and 0.6 µg/g than the solvent control whereas sand removal at 0.3 µg/g was similar with the solvent control. Black imported fire ants showed repellency at serial concentrations ranging between 19.5 and 0.15 µg/g whereas the hybrid imported fire ants showed repellency between 19.5 and 4.9 µg/g. In DEET treatments, red and black imported fire ants showed repellency at dosages of 125 to 62.5 µg/g, whereas the treatment failed at the dose of 15.6 µg/g in hybrid fire ants. (E/Z)-3-butylidenephthalide with LC50 values of 11 and 16.4 µg/g was toxic against red and black imported fire ants, respectively, followed by hybrid imported fire ants (LC50 = 104.7 µg/g). Fipronil with LC50 values of 0.49, 0.33, and 0.53 µg/g against red, black, and hybrid fire ants, respectively, was more toxic than (E/Z)-3-butylidenephthalide. In residual bioassay, toxic activity lasted for 3 weeks at dosages of 250 and 500 μg/g against HIFA. The high repellency and toxicity of (E/Z)-3-butylidenephthalide against imported fire ants makes it a natural compound of interest for further evaluation under natural field conditions. [ABSTRACT FROM AUTHOR]

Forest fires are a major global environmental problem, especially for forest ecosystems and specifically in Mediterranean climate zones. These fires can seriously impact hydrologic processes and soil erosion, which can cause water pollution and flooding. The aim of this work is to assess the effect of forest fire on the hydrologic processes in the soil, depending on soil properties. For this purpose, the infiltration rate has been measured by ring infiltration tester, and the hydrophobicity has been quantified by the "water drop penetration time" method in several soils of burnt and unburnt forest areas in the Mediterranean mountains. The infiltration rates obtained are higher in burnt than in unburnt soils (1130 and 891 mm·h−1, respectively), which contradicts most of the research in Mediterranean climates in southeast Spain with calcareous soils. Burnt soils show no hydrophobicity on the surface, but it is there when the soil is excavated by 1 cm. Additionally, burnt soils reveal a low frequency of hydrophobicity (in less than 30% of the samples) but more severe hydrophobicity (above 300 s); whereas, in unburnt soils, the frequency is higher (50%) but the values of hydrophobicity are lower. The results obtained clearly show the infiltration processes modified by fire, and these results may be useful for land managers, hydrologists, and those responsible for decision-making regarding the forest restoration of burnt land. [ABSTRACT FROM AUTHOR]

This study aimed to assess the efficiency of the use of α-pinene and essential oils of Gaultheria procumbens, Juniperus communis, Protium heptaphyllum, and Protium pallidum in treating corn seeds (Zea mays) under storage conditions for the management of Sitophilus zeamais. Contact toxicity, fumigation, repellency, persistence, and residual effects of the targeted essential oil and phytocompound on germination were performed. G. procumbens oil, high in methyl salicylate (96%), was the most toxic in contact tests, with an LC50 of 26.83 µL/20 g. P. heptaphyllum oil, containing 40.1% limonene, was the second most toxic with an LC50 of 45.78 μL/20 g. When test separately, α-pinene was more toxic than J. communis oil, which has 67% α-pinene. P. pallidum oil, with 31.17% o-cimene, also showed toxicity. In fumigation tests, the toxicity order was G. procumbens ≥ P. heptaphyllum > α-pinene > J. communis > P. pallidum. All products were repellent. G. procumbens had the longest persistence (71 days), while J. communis and α-pinene had shorter persistence. J. communis oil and α-pinene did not affect corn seed germination or vigor. The findings are crucial for managing S. zeamais in stored maize and determining the appropriate use of natural insecticides without affecting their ability to germinate and grow. [ABSTRACT FROM AUTHOR]

Simple Summary: Drosophila suzukii (Diptera: Drosophilidae) is an invasive pest that lays eggs in ripe fruits. The short generation time, high fertility, and wide host range allows this species to cause important yield losses. Essential oils, extracted from a number of plant species, have been studied for their attractiveness to and deterrence of D. suzukii. In this study, we found clary sage oil exhibited dose-dependent repellency against both D. suzukii adults and larvae. Also, we identified that linalyl acetate and linalool were two major constituents of clary sage oil by GC-MS. Furthermore, we detected that both linalyl acetate and linalool repelled D. suzukii adults and larvae. In addition, we examined the electroantennography (EAG) responses of D. suzukii to clary sage oil, linalyl acetate, and linalool. These results suggest clary sage oil and its constituents linalyl acetate and linalool could be potential repellents for the management of D. suzukii. Drosophila suzukii (Diptera: Drosophilidae), spotted-wing drosophila, poses a significant threat to soft-skinned fruit crops in the Americas, Europe, Africa, and Oceania, as well as in Asia. The application of chemical insecticides is the primary control strategy for D. suzukii; however, resistance has developed with the indiscriminate use of chemical insecticides. Essential oils, considered potential alternatives to pesticidal strategies, exhibit potent toxic and sublethal behavioral effects against numerous pests, including D. suzukii. Clary sage oil repels a variety of agricultural and household pests; however, whether it has a repellent effect against D. suzukii remains unknown. Here, we found that clary sage oil exhibited dose-dependent repellency against D. suzukii adults in a T-maze assay, a two-choice assay and a two-choice attraction assay. Also, clary sage oil showed a significant repellent effect against D. suzukii larvae. Next, we explored the chemical constituents of clary sage oil by GC-MS and identified two major constituents, linalyl acetate (40.03%) and linalool (23.02%). Furthermore, the behavioral assays of linalyl acetate and linalool showed that both compounds conferred comparable repellency against D. suzukii adults and larvae. Finally, we found clary sage oil, linalyl acetate, and linalool elicited EAG responses in D. suzukii, especially clary sage oil, suggesting the repellency was mediated by the olfactory system. These findings indicate that D. suzukii shows olfactory-based behavioral avoidance of clary sage oil, linalyl acetate, and linalool. Clary sage oil and its major constituents may be possible alternatives in the management of D. suzukii. [ABSTRACT FROM AUTHOR]

The sunn pest, Eurygaster integriceps Put. (Hem.: Scutelleridae) is one of the most important pests of wheat in Iran and the Middle East. At present, the control of this pest in the country is based on chemical control, which due to the limitation of using chemical pesticides, the use of other eco-friendly control methods, including the cultivation of companion plants is considered. Therefore, in this study, the effect of windbreakers, especially pine trees, around wheat fields, on the infestation of the sunn pest was investigated during 2019 and 2020. In this experiment, three treatments were considered in three replications, including three areas surrounded by pine trees, three areas surrounded by non-pine trees, and three areas without windbreakers. In each area, sampling of the mother's bug was performed several times by quadrate and insect net during an outbreak of pest in two consecutive years. Furthermore, the correlation of meteorological parameters with the pest density at sampling dates in different treatments was investigated. As well as, in the laboratory studies, the repellency of pine essential oils on the adult insect was tested in three concentrations, including LC10, LC25, LC50 by olfactometer and wind tunnel. The results of field sampling showed that the density of the pest in fields with windbreakers, especially pine windbreakers, was much lower than the farms without windbreakers in both years. Bioassay results showed that pine trees essential oils have a high lethal effect on adult bug, and the values of LC50, LC25 and LC10 were 362, 82 and 21 µl/l of air, respectively. The results also showed that increasing the concentration of essential oils increased the rate of repellency. The results of the correlation of meteorological parameters with adult bug density showed that in all treatments, there was a positive and significant correlation between sunn pest density and wind direction in both studied years. Therefore, based on this study's results, planting of pine trees around wheat fields can reduce infestation of sunn pest, and the repellency properties of the volatile compounds of this plant on the pest are probably adequate. [ABSTRACT FROM AUTHOR]

Deer species can cause serious damages to trees through browsing and antler rubbing, and these impacts can generate significant economic losses. As a tool to minimize damages to trees by deer, repellents based on odor, visual and/or taste stimulus have been developed and tested. Repellents vary greatly in terms of costs, forms of use, duration, and/or the local context. Thus, selection of the most-effective repellent to each situation should consider the local environmental and socioeconomic contexts. Pyrazine analogs have been recognized to induce avoidance and fear-related behaviors in deer. These compounds are also found in ordinary and daily-use products, such as coffee, which can be easily obtained. The marsh deer (Blastocerus dichotomus) is the largest native deer of South America. The southernmost population of this species is found in the lower Delta of the Paraná River in Argentina, a large wetland highly modified due to commercial afforestation of Salicaceae. Local forestry producers usually report damage to plantations attributed to marsh deer, with a minor fraction of these producers perceiving high levels of damage and economic losses. We tested an easy-to-install repellent system based on coffee grounds by conducting trials focused on four captive marsh deer. The trials consisted in offering pellets of grain and fiber to deer, dividing the overall ration into two identical factions separated by 15 meters within the enclosure. In the "repellent site", a subset of the regular food was placed on the ground and treated with the repellent, whereas the other subset, also located in the ground but not treated, was used as the "control site". Whereas deer individuals presented alert behavior (50-100% of the times) after approaching the repellent site, this behavior was never observed at the control site. Significant differences were found among individuals probably due to a dominance interaction inside the group. The weight of food remains in the repellent site was significantly higher than in the control site at the end of the study. A repellency system based on coffee grounds could be an economic solution to be used by forestry producers of the Paraná River delta or by anyone interested in diminish damages to particular resources. In addition, it is a biodegradable option with insignificant environmental impact and could be especially useful to be applied at small spatial scales, since it requires domestic materials and a relatively limited installation cost in terms of time spent to set up the system. [ABSTRACT FROM AUTHOR]

Essential oils (EOs) are volatile products derived from the secondary metabolism of plants with antioxidant, antimicrobial, and pesticidal properties. They have traditionally been used in medicine, cosmetics, and food additives. In agriculture, EOs stand out as natural alternatives for pest control, as they show biocidal, repellent, and antifeedant effects. However, they are highly volatile compounds and susceptible to oxidation, which has limited their use as pesticides. This has led to exploring micro- and nano-scale encapsulation to protect these compounds, improving their stability and allowing for a controlled release. Various encapsulation techniques exist, such as emulsification, ionic gelation, and complex coacervation. Nanoemulsions are useful in the food industry, while ionic gelation and complex coacervation offer high encapsulation efficiency. Materials such as chitosan, gelatin-gum-Arabic, and cyclodextrins are promising for agricultural applications, providing stability and the controlled release of EOs. Encapsulation technology is still under development but offers sustainable alternatives to conventional agrochemicals. This article reviews the potential of EOs in pest management and encapsulation techniques that enhance their efficacy. [ABSTRACT FROM AUTHOR]

Tribolium castaneum is a challenging pest of stored products, causing significant economic losses. The present study explored the efficacy of Coridothymus capitatus essential oil and its primary constituent, carvacrol, as eco-friendly alternatives for managing this pest. To evaluate their insecticidal potential, repellency, fumigant toxicity, and antifeedant properties, progeny inhibition assays were performed. Carvacrol exhibited superior repellency compared to the essential oil, achieving a 92% repellency rate at 2 mg/cm2. Both compounds demonstrated significant fumigant toxicity against T. castaneum, with LC50 values of 168.47 and 106.5 μL/L for the essential oil and carvacrol, respectively, after 24 h. Carvacrol also outperformed the essential oil in antifeedant activity, inducing an 80.7% feeding deterrence at 1.17 mg/g. Moreover, both treatments effectively suppressed the development of the pest's progeny. These results collectively underscore the potent insecticidal properties of C. capitatus essential oil and carvacrol, particularly carvacrol, as promising candidates for the sustainable management of T. castaneum in stored product protection. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the effectiveness of citronella essential oil as a repellency agent in controlling pest attacks on plants. The method used was systematic literature review with data collection through literature studies to collect various types of existing literature to be extracted according to the research title. The findings indicated that citronella essential oil has potential as an environmentally friendly and sustainable pest control method. However, several challenges such as the stability of the oil in the open and the need for periodic reapplication need to be addressed. With an integrated approach that takes into account relevant environmental and technical factors, the use of citronella essential oil can become an integral part of a more effective pest control strategy in agriculture. [ABSTRACT FROM AUTHOR]

Dermestes maculatus accounts for about 71.5% of dried fish infestation in most of the producing areas with a substantial loss in both dry weight and nutritional value. The study aimed to evaluate the repellent effect of oils extracted from Garlic (Allium sativum), Coconut (Cocos nucifera), Ginger (Zingiber officinale), Jatropha (Jatropha curcas), and Neema (Azadirachta indica) on Dermestes maculatus larvae in smoke-dried Protopterus annectens. The extracted oils from each plant were applied to the fish at varying concentrations of 0.001, 0.004, 0.016, 0.064, and 0.256 ml/g fish in triplicates. Late instar larvae of D. maculatus were introduced into Kilner jars containing fish treated with these oils and repellency was monitored for 24 hrs. Repellency was highest (87%) in A. sativum oil and lowest (59%) in A. indica oil at the highest concentration (0.256 ml/g of fish) within 24 hrs. of exposure. Furthermore, an increasing trend in repellency was observed with increasing concentrations of oils from all the plants used. The order of repellency performance was A. sativum > C. nucifera > Z. officinale > J. curcas > A. indica, starting with the highest to the lowest. Therefore, this study demonstrates the repellent properties of the oils in offering effective protection against infestation and damage by D. maculatus, suggesting that the oils can be utilized in post-harvest preservation of smoke-dried fish.

Abstract Encapsulation of essential oils (EOs) is an important strategy that can be applied to intensify the stability and efficiency of these compounds in integrated pest management. The present study aimed to investigate the sub-lethal activity of polymer-based EOs nanoparticles against red flour beetle, Tribolium castaneum adults as an important critical pest of stored products. Chitosan nanoparticles (CSNPs) containing garlic and cinnamon essential oils (GEO and CEO) prepared using the ionic cross-link technique. Stability of nano-formulations evaluated over temperature and storage time. The fumigant effect (LC10, LC20, LC30) and contact toxicity (LC10, LC15, LC25) determined. In addition, the contact toxicities of EOs and their nanoparticles on nutritional indices evaluated. An olfactometer used to assess the repellent activity of EOs and EOs loaded in CSNPs (EOs@CSNPs) in sub-lethal fumigant concentrations. Characterization results showed GEO loaded in CSNPs has particle size of 231.14 ± 7.55 nm, polydispersity index (PDI) value of 0.15 ± 0.02, encapsulation efficiency (EE) percentage of 76.77 ± 0.20 and zeta potential of − 18.82 ± 0.90 mV, in which these values for the CEO loaded in CSNPs (CEO@CSNPs) changed to 303.46 ± 0.00 nm, 0.20 ± 0.05, 86.81 ± 0.00% and − 20.16 ± 0.35 mV, respectively. A lower PDI value for both CSNPs showed an appropriate NPs size distribution. Furthermore, NPs size and encapsulation efficiency did not change in various temperatures and during four months which confirm good stability of the EOs@CSNPs. In LC30 of GEO@CSNPs, the maximum repellency was determined as 66.66 ± 3.33. Among nutritional indices, in LC25 of GEO@CSNPs, the relative growth rate (RGR) (0.011 ± 0.003 mg.mg−1.day−1), relative consumption rate (RCR) (0.075 ± 0.004 mg.mg−1.day−1) and feeding deterrence index (FDI) (54.662 ± 1.616%) were more affected, so GEO@CSNPs was more effective than CEO@CSNPs. The results of repellent and anti-dietary activities of EOs and EOs@CSNPs confirmed the higher repellency and adverse effectivity on nutritional indices of Tribolium castaneum pest treated with EOs@CSNPs compared to free EOs. In conclusion, the NPs form of GEO and CEO can be a novel and efficient carrier for improving the repellent and anti-nutritional activities of EOs.

Aphids are important pests of many crops. However, the use of chemical insecticides has provoked ecological and health problems, thus the valuation of natural products becomes an interesting alternative. Compost teas are organic products that are viewed as substitutes for common pesticides. The present study aims to screen the potential insecticidal effect of garden waste compost tea, through in vitro and in silico approaches. Five concentrations of a compost tea (20, 40, 60, 80 and 100%) were tested against Aphis craccivora, in comparison to negative and positive controls. The repellency and toxicity tests were conducted under laboratory conditions. Moreover, an evaluation of the inhibitor capacity of some compost compounds against acetylcholinesterase was carried out using molecular docking. Results revealed that compost had a very weak insecticidal effect against A. craccivora (where the corrected mortality did not exceed 24%) compared to the tested chemical pesticide. Furthermore, the repellency test showed that the compost had some repellency effect in comparison to the tested chemical pesticide which had an attractant effect. Concerning the results of the molecular docking, pirimicarb (active molecule of pesticides) recorded a better S score than the three compost compounds. [ABSTRACT FROM AUTHOR]

Copyright of Boletín Latinoamericano y del Caribe de Plantas Medicinales y Aromáticas is the property of Universidad de Santiago de Chile and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Rhyzopertha dominica and Tribolium castaneum are two significant insect pests that affect the quality, quantity, and commercial value of stored products. The aim of this study was to assess the chemical composition, repellency, and insecticidal activity of Pinus halepensis leaf EO on adults of Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). The EO of P. halepensis Mill. was extracted using hydrodistillation and analyzed for its chemical composition by GC-MS. The major components identified were 1-nonadecene (25.51%), 1-hexadecene (20.79%), pimaric acid (16.71%), and palmitic acid (12.47%). The repellency test was determined by the area-preference method. P. halepensis EO exhibited significant repellent activity against T. castaneum and R. dominica. It showed high class IV repulsion rates, reaching 63.60% against T. castaneum and 66.50% against R. dominica. The repellent effect was most potent at the highest concentration tested (16 µL/mL), achieving a 100% efficacy against T. castaneum after 4 h and after 3 h against R. dominica. The contact toxicity test was carried out by impregnating filter paper disks with increasing doses of the EO studied. P. halepensis EO was the most toxic against R. dominica (LC50 = 17.11 µL/mL, LC90 = 30.02 µL/mL) and T. castaneum (LC50 = 20.92 µL/mL, LC90 = 32.18 µL/mL) after 96 h of exposure. The ability of P. halepensis EO to repel and eliminate insects suggests that it could be used as a new treatment to prevent insect infestations of R. dominica and T. castaneum.

Soybean oil is a significant alternative to synthetic chemicals for environmentally friendly and sustainable pest control. This study evaluated soybean oil and its fatty acids (palmitic, oleic, and stearic acids; individually) for their acaricidal and repellent effects against Panonychus citri (Tetranychidae) and its predators [Neoseiulus californicus and Neoseiulus barkeri [Phytoseiidae]) using laboratory foliar dipping and topical spray methods. The LC50 (Lethal Concentration) values for palmitic, oleic, stearic acids, and soybean oil against P. citri were 0.86%, 0.95%, 0.56%, and 0.05% for LDM (Leaf-dipping Method) and 11.92%, 5.34%, 1.46%, and 0.07% for TSM (Topical Spray Method). Soybean oil has maximum attraction (46.67 ± 3.6%) and significantly higher acaricidal effectiveness (46.25 ± 0.98%) compared to acids except oleic acid (50.83 ± 1.22%) against P. citri. Soybean oil showed the least toxicity, with the highest LT50 (Lethal Time) values for N. californicus (LDM: 1.19 h, TSM: 1.27 h). While soybean oil caused a less significant reduction in fertility and lower lethal efficacy (0.83 ± 0.83%) on predatory mites compared to P. citri. Compared to soybean oil, oleic acid reduces fertility rate (27 ± 1.60%) and is an effective repellent (65-75%) against N. californicus and N. barkeri and reduces prey consumption (15-16%) and laying eggs (0.75 ± 0.47) on treated surfaces compared to other treatments. Palmitic acid increases prey consumption (27.5 ± 3.28%) and fertility rates (5.00 ± 0.71) of N. californicus. Palmitic acid, despite being less toxic to P. citri, effectively repels predators, while soybean oil and oleic acid have stronger repellent effects. Leaf dipping was less effective than topical spray. Soybean oil, with its lower mortality rates and sublethal effects on reproduction and behavior, is a strong candidate for integrated pest management strategies. Oleic and palmitic acids, though effective, have repellency to beneficial predators.

The repellent capacity against Sitophilus zeamais and the in vitro inhibition on AChE of 11 essential oils, isolated from six plants of the northern region of Colombia, were assessed using a modified tunnel-type device and the Ellman colorimetric method, respectively. The results were as follows: (i) the degree of repellency (DR) of the EOs against S. zeamais was 20–68% (2 h) and 28–74% (4 h); (ii) the IC50 values on AChE were 5–36 µg/mL; likewise, the %inh. on AChE (1 µg/cm3 per EO) did not show any effect in 91% of the EO tested; (iii) six EOs (Bursera graveolens—bark, B. graveolens—leaves, B. simaruba—bark, Peperomia pellucida—leaves, Piper holtonii (1b*)—leaves, and P. reticulatum—leaves) exhibited a DR (53–74%) ≥ C+ (chlorpyrifos—61%), while all EOs were less active (8–60-fold) on AChE compared to chlorpyrifos (IC50 of 0.59 µg/mL). Based on the ANOVA/linear regression and multivariate analysis of data, some differences/similarities could be established, as well as identifying the most active EOs (five: B. simaruba—bark, Pep. Pellucida—leaves, P. holtonii (1b*)—leaves, B. graveolens—bark, and B. graveolens—leaves). Finally, these EOs were constituted by spathulenol (24%)/β-selinene (18%)/caryophyllene oxide (10%)—B. simaruba; carotol (44%)/dillapiole (21%)—Pep. pellucida; dillapiole (81% confirmed by 1H-/13C-NMR)—P. holtonii; mint furanone derivative (14%)/mint furanone (14%)—B. graveolens—bark; limonene (17%)/carvone (10%)—B. graveolens—leaves. [ABSTRACT FROM AUTHOR]

The brown planthopper (Nilaparvata lugens, BPH), white-backed planthopper (Sogatella furcifera, WBPH) and small brown planthopper (Laodelphax striatellus, SBPH) are three serious pests in the rice cultivation of Asia. Using plant extracts or their derived compounds to control rice planthoppers could be sustainable, as they are reliable sources of bio-pesticide. In this study, we evaluated the repellency of eighteen plant ethanolic extracts and their derived compounds against these planthoppers. Our results indicated that ethanolic extracts from Litsea cubeba, Zanthoxylum bungeanum, Piper nigrum, Curcuma longa, and Cinnamomum camphora possessed repellency effects on female adults and nymphs of BPH. The petroleum ether fractions of L. cubeba, Z. bungeanum, and C. longa ethanolic extracts, the ethyl acetate fractions of P. nigrum ethanolic extracts were analyzed with GC–MS. Based on earlier reports and our GC–MS analysis, nine compounds derived from the above ethanolic extracts were selected to screen their repellency to BPH in H-tube olfactometer. Two effective compounds, 1-(2-hydroxy-4, 6-dimethoxyphenyl)-ethanone (xanthoxyline) and caryophyllene oxide, were chosen to investigate their repellency on three species of rice planthoppers. The two compounds showed significant repellency to BPH, WBPH and SBPH under laboratory and greenhouse conditions at 10–1000 ppm. Field experiments showed that the releasers which contained 1000 ppm xanthoxyline or caryophyllene oxide suppressed the planthoppers population significantly. Additionally, xanthoxyline and caryophyllene oxide showed no adverse effect on the predator, Cyrtorhinus lividipennis, in the laboratory and field conditions. These results may contribute to the IPM program for the development of green planthoppers repellents applied in the rice field. [ABSTRACT FROM AUTHOR]

The mosquito Aedes aegypti, known to transmit important arboviral diseases, including dengue, chikungunya, Zika and yellow fever. Given the importance of this disease vector, a number of control programs have been proposed involving the use of the sterile insect technique (SIT). However, the success of this technique hinges on having a good understanding of the biology and behavior of the male mosquito. Behavioral responses of Ae. aegypti male populations developed for SIT technology were tested under laboratory conditions against chemical and natural irritants and repellents using an excito-repellency (ER) chamber. The results showed that there were no significant behavioral escape responses in any of the radiation-sterilized maleAe. aegypti test populations when exposed to citronella, DEET, transfluthrin, and deltamethrin, suggesting that SIT did not suppress the expected irritancy and repellency (avoidance) behaviors. The type of information reported in the current study is vital in defining the effects of SIT on vector behavior and understanding how such behavior may influence the success of SIT technology with regard to other vector control interventions. [ABSTRACT FROM AUTHOR]

The effect of sporal and mycelial VOCs of entomopathogenic fungi of the genus Lecanicillium on primary behavioral responses of the predatory bug Orius laevigatus was studied in laboratory experiments. Free choice of adult Orius bugs between the sporulating mycelium and the nutrient medium without the fungus was evaluated in Petri dishes (24 h, in the presence of S. cerealella eggs and a bean leaf) and in 2-chamber olfactometers (1 h, without food). Repellent response in the bugs was caused by the mycelium of three strains: Lecanicillium lecanii strain Vl 29, L. dimorphum strain ARSEF 2332, and L. attenuatum strain Vit 71, with the index of aggregation IA ranging from −40.7 to −50 (P < 0.05). A significant attractive response with an IA value of +43.3 was caused by L. lecanii strain Vl 5. The response of O. laevigatus to VOCs of Lecanicillium fungi after 1 h in 2-chamber olfactometers was predominantly neutral, with pronounced repellency observed only for L. lecanii strain Vl 29 (IA = −72) and L. dimorphum strain ARSEF 8057 (IA = −36.8). [ABSTRACT FROM AUTHOR]

Chlorpyrifos is widely used in agricultural and building industries to control many insects including termites. However, its low aqueous solubility and tendency to decompose under sunlight results in decrease in its efficiency. In the present study, chlorpyrifos was encapsulated into nano-sized poly (styrene-co-maleic anhydrite) using a mini-emulsion in-situ polymerization method to improve the effective utilization rate. The termiticidal properties of nanocapsules at different concentrations (1 - 25 wt%) were tested against subterranean termite; Coptotermes curvignathus. Results of Choice bioassays shows that chlorpyrifos nanocapsules are strongly toxic to Coptotermes curvignathus. The filter paper feeding inhibition and repellent bioassay show a significant feeding inhibition (> 60 %) at lowest concentration of chlorpyrifos nanocapsules. The highest mortality rate of termites (90 %) after 24-h exposure was observed in the sample treated with the highest concentration of chlorpyrifos nanocapsules (25 wt%). Results obtained from this study show that chlorpyrifos nanocapsules have a strong termiticidal property against Coptotermes curvignathus. This indicates that the nanoencapsulation of biocides chlorpyrifos opens a real potential of new and advanced wood preservation technology.

Malaria, which is transmitted by the mosquito Anopheles gambiae, has long been a major public health concern in the tropics. Chemicals used to control A. gambiae have caused significant harm to the environmental and non-target organisms. Furthermore, these mosquitoes have demonstrated a high level of resistance. This study evaluated the adulticidal, ovicidal and repellent potencies of leaf extracts of Alchornea cordifolia against A. gambiae. It was observed that 5 mg/ml of the leaf extract induced about 94% mortality in the adult A. gambiae, 0.8 gm/cm3 of the leaf extract repelled 95% of the mosquitoes within 15 minutes and 0.6 mg/ml of the leaf extract completely inhibited hatching of mosquito ova. Evidently, A. cordifolia leaf extracts showed a good efficacy in the management of A. gambiae in this study. More research is needed to determine its mode of action, synergism with other products, and efficacy in actual field conditions.

Essential oils (EOs) are volatile products derived from the secondary metabolism of plants with antioxidant, antimicrobial, and pesticidal properties. They have traditionally been used in medicine, cosmetics, and food additives. In agriculture, EOs stand out as natural alternatives for pest control, as they show biocidal, repellent, and antifeedant effects. However, they are highly volatile compounds and susceptible to oxidation, which has limited their use as pesticides. This has led to exploring micro- and nano-scale encapsulation to protect these compounds, improving their stability and allowing for a controlled release. Various encapsulation techniques exist, such as emulsification, ionic gelation, and complex coacervation. Nanoemulsions are useful in the food industry, while ionic gelation and complex coacervation offer high encapsulation efficiency. Materials such as chitosan, gelatin-gum-Arabic, and cyclodextrins are promising for agricultural applications, providing stability and the controlled release of EOs. Encapsulation technology is still under development but offers sustainable alternatives to conventional agrochemicals. This article reviews the potential of EOs in pest management and encapsulation techniques that enhance their efficacy.

The mosquito Aedes aegypti, known to transmit important arboviral diseases, including dengue, chikungunya, Zika and yellow fever. Given the importance of this disease vector, a number of control programs have been proposed involving the use of the sterile insect technique (SIT). However, the success of this technique hinges on having a good understanding of the biology and behavior of the male mosquito. Behavioral responses of Ae. aegypti male populations developed for SIT technology were tested under laboratory conditions against chemical and natural irritants and repellents using an excito-repellency (ER) chamber. The results showed that there were no significant behavioral escape responses in any of the radiation-sterilized male Ae. aegypti test populations when exposed to citronella, DEET, transfluthrin, and deltamethrin, suggesting that SIT did not suppress the expected irritancy and repellency (avoidance) behaviors. The type of information reported in the current study is vital in defining the effects of SIT on vector behavior and understanding how such behavior may influence the success of SIT technology with regard to other vector control interventions.

Essential oils (EOs) obtained from plants have the potential to be environment-friendly alternatives to synthetic insecticides in agriculture. Tribolium castaneum (Herbst) is a cosmopolitan pest that causes the loss of a major proportion of stored crops. Therefore, we studied the insecticidal and repellent effects of EOs derived from the plants viz. Eucalyptus rudis, Eucalyptus crebra, and Melaleuca genistifolia against larvae and adults of T. castaneum. Essential oils were derived from the leaves of each plant using hydro-distillation. Gas chromatography-mass spectrometry (GC-MS) of the extracted EOs revealed that eucalyptol, viridiflorol, α-terpineol, and eugenol methyl comprised the major components of the EOs. However, the composition and quantity of the compounds varied across EOs. Specifically, EOs derived from E. rudis exhibited the highest fumigation toxicity against adult and larval T. castaneum, followed by M. genistifolia and E. crebra. In the presence of wheat grains, fumigation toxicity against T. castaneum declined by nearly threefold. Contact toxicity assays revealed that EOs from E. rudis were overall the most effective against the pest (LC50: 0.392 μL/cm2 for adult; LC50: 0.471 μL/cm2 for larva) followed by M. genistifolia (LC50: 0.424 μL/cm2 for adult; LC50: 0.478 μL/cm2 for larva) and E. crebra (LC50: 0.471 μL/cm2 for adult; LC50: 0.515 μL/cm2 for larva). The LC50 value of each EO was up to five times lower in adults than in larvae. Melaleuca genistifolia was the most effective repellent against T. castaneum adults; however, its effectiveness decreased with increasing exposure time. In conclusion, the EOs of E. rudis, E. crebra, and M. genistifolia were all viable green biopesticide alternatives to synthetic insecticides. [ABSTRACT FROM AUTHOR]

BACKGROUND: An important component of the biological activity of pyrethroids, when used in disease vector control, is excito‐repellency. In this study, behavioral differences between insecticide susceptible (Orlando) and pyrethroid resistant (Puerto Rican) strains of Aedes aegypti were explored in a round glass arena using fabrics treated with permethrin, etofenprox, deltamethrin, or DDT. Repellency was evaluated across several variables, including the time to first flight (TFF), number of landings (NOL), total flight time (TFT), and maximum surface contact (MSC), all by video analysis. RESULTS: Results from the Orlando strain indicated they were less likely than the Puerto Rican strain to tolerate tarsal contact with the treated fabrics. All four response variables indicated that the mosquito flight and landing behavior was most affected by pyrethroid resistance [knockdown resistance (kdr)] status. In other experiments, mosquitoes were surgically altered, with antennae ablated bilaterally, and these mosquitoes were more likely to stay on the treated surfaces for longer periods of time, irrespective of any chemical exposure. There were also differences in the responses to antennal ablation between the two strains of mosquitoes, indicating that resistance factors, probably kdr, influence the reactivity of mosquitoes to pyrethroid and DDT treatments, and that it was not completely negated by antennal ablation. CONCLUSIONS: These findings confirm the role of antennal olfactory components in the expression of excito‐repellent behaviors, and also support the hypothesis that excito‐repellency from pyrethroid/DDT exposure is probably due to a combination of sublethal neurotoxic excitation and interactions with the olfactory system. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

BACKGROUND: Pyrethroids are synthetic insecticides with low mammalian toxicity and broad‐spectrum activity across insects. One major challenge with pyrethroids is their perceived repellency. This perception can influence decisions made by pest control operators, especially when insecticides are used to reduce insect entry into or movement within structures. One major indoor pest that has been repeatedly shown to be repelled by some pyrethroids is the German cockroach, Blattella germanica. However, most experiments evaluating pyrethroid repellency in the German cockroach have used end‐point assays, which do not provide information on the movement that led to the final position. Therefore, we evaluated the kinetic behavioral response of field‐collected German cockroaches to five pyrethroid‐based products and their active ingredients (A.I.) in open behavioral arenas using advanced video tracking software. In addition, in an effort to compare our free‐moving experiments with end‐point assays, we evaluated sheltering behavior using two‐choice harborage arrestment assays where German cockroaches were provided a choice between pyrethroid‐treated and untreated shelters. RESULTS: All pyrethroid‐formulated products and their respective A.I.'s failed to affect field‐collected German cockroach movement behavior in free‐moving assays, while positive controls (DEET, corn mint oil) resulted in reduced time spent by German cockroaches in treated areas. However, despite their willingness to move over pyrethroids‐treated surfaces, field‐collected German cockroaches displayed a reduced propensity to arrest on pyrethroids treated tents. CONCLUSION: While most pyrethroids/pyrethroid‐formulated products affected German cockroach arrestment, pyrethroids and pyrethroid‐formulated products failed to change German cockroach movement behavior in free‐moving assays. These results indicate the pyrethroids tested act as contact irritants rather than true‐spatial repellents on field‐collected German cockroaches. This distinction is critical to refining pest management strategies involving pyrethroids. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Trogoderma granarium is a very destructive pest of stored grain and cereals in hot and dry climates of the world. A wide range of hard chemistries and selective fumigants are in use to control this destructive pest, but the residual effects of these chemicals have serious health issues. The current investigation was carried out at the Grain Research, Training, and Storage Management Cell in the Integrated Pest Management Entomology laboratory in the College of Agriculture at Bahauddin Zakariya University, Bahadur Sub Campus Layyah. The study was conducted during the period of 2017-2018, to assess the insecticidal mortality and repellency properties of various plant extracts against the larvae (grub) of T. granarium.. Three plants viz; Nigella sativa (kalonji), Curcuma longa (turmeric) and Peganum harmala (hermal) were used with three different concentrations 3%, 6% and 12%. These plants are considered safer for the environment and have no mammalian toxicity. The post-treatment data regarding mortality and repellency was recorded at an interval of 24, 48, 72, 96 and 120 hours. The results showed that N. sativa extract was more effective in the mortality of T. granarium grubs, followed by C. longa and P. harmala having mortality of 46.67±3.33, 39.0±1.00 and 35.0±4.00 %, respectively. Percentage mortality was recorded after 96 hours, was 13±3.33, 20±0.00, and 43±3.33 % at the concentration of 3%, 6% and 12% respectively. The minimum corrected mortality was recorded at the lowest time period after 24 hours in all the plant extracts. In comparison among extracts, kalonji showed maximum mortality followed by turmeric and hermal respectively. The overall results showed that corrected mortality increases with an increase in concentration and time interval. The maximum repellent effect was recorded in kalonji extract while minimum repellency was observed in hermal extract. This information is useful for the successful management of T. granarium. [ABSTRACT FROM AUTHOR]

Anticarsia gemmatalis is the most important soybean pest in various countries of America controlled mainly with synthetic insecticides. Effective management alternatives to control and avoid of insecticide resistance are needed against this pest. The toxicity, behavioral response, and respiration of A. gemmatalis larvae exposed to lemongrass essential oil (LEO) and its components were investigated. The principal components of LEO were neral, citral, and geranyl acetate with 31.5%, 26.1%, and 2.27% abundance, respectively. Larvae contact toxicity was found 36 h after exposure with LEO (LD50= 14.7 µg insect−1), citral (LD50= 4.56 µg insect−1), and geranyl acetate (LD50= 15.9 µg insect−1). Insects exposed to LEO and its components reduced locomotion and orientation to treated surfaces. Also, A. gemmatalis larvae reduced their respiration after treatment with LEO and components. These results demonstrate that LEO, citral, and geranyl acetate cause toxic and repellent effects on A. gemmatalis, indicating their potential to control this soybean pest. [ABSTRACT FROM AUTHOR]

A study was conducted to assess the persistence and repellency potentials of seed oils of desert date (Balanites aegyptiaca) and neem (Azadirachta indica) against the tropical warehouse moth (Ephestia cautella walker), Dichlorvos (DDVP) was used as a positive control. Different concentrations of neem and desert date oils (10, 15, 20, and 25 ml/l) and DDVP (10 ml/l) were used to treat 100 g of maize grains, while repellency of the insect to the oils on treated filter paper was also assessed at the same dose rates, arranged in a completely randomized design with three replications. The data were analyzed using analysis of variance (ANOVA), and means were separated using the New Duncan Multiple Range Test (NDMRT) at 0.05 %. Results showed that Dichlorvos, desert date and neem seed oils caused 100 % mortality, and repellency of 33.33, 86.67 and 66.67 %, respectively after 72 hours. The oils remain effective for 12 weeks with percent mean damage (80.71 % and 92.36 %) and weight loss (29.76 % and 59.79 %) when treated with a high dose (25ml/l) and longer duration of 12 weeks, respectively while, the control has 81.18 and 34.36 % of grain damage and weight loss, respectively. The positive control (DDVP) has 63.89 % and 21.49 % of grain damage and weight loss. It is, therefore, concluded that desert date and neem seed oils significantly caused E. cautella mortality. This has proven that desert date and neem seed oils provide good protection to maize grains and could be considered as a substitute to Dichlorvos. [ABSTRACT FROM AUTHOR]

Chlorpyrifos is widely used in agricultural and building industries to control many insects including termites. However, its low aqueous solubility and tendency to decompose under sunlight results in decrease in its efficiency. In the present study, chlorpyrifos was encapsulated into nano-sized poly (styrene-co-maleic anhydrite) using a mini-emulsion in-situ polymerization method to improve the effective utilization rate. The termiticidal properties of nanocapsules at different concentrations (1 - 25 wt%) were tested against subterranean termite; Coptotermes curvignathus. Results of Choice bioassays shows that chlorpyrifos nanocapsules are strongly toxic to Coptotermes curvignathus. The filter paper feeding inhibition and repellent bioassay show a significant feeding inhibition (> 60 %) at lowest concentration of chlorpyrifos nanocapsules. The highest mortality rate of termites (90 %) after 24-h exposure was observed in the sample treated with the highest concentration of chlorpyrifos nanocapsules (25 wt%). Results obtained from this study show that chlorpyrifos nanocapsules have a strong termiticidal property against Coptotermes curvignathus. This indicates that the nanoencapsulation of biocides chlorpyrifos opens a real potential of new and advanced wood preservation technology. [ABSTRACT FROM AUTHOR]

Abstract Despite its beneficial properties and the efficiency of essential oil in controlling mosquitoes and other hematopoietic insects, this biocontrol agent has several significant limitations, ranging from its chemical instability to its short protection time and sensitivity to oxidation. This research aimed to address these limitations by altering the surface functionality using encapsulated Vitex negundo essential oil (VnEO). The VnEO was extracted by hydrodistilation and analysed by GC–MS. The oil was β-cyclodextrin (β-CD) encapsulated and monochlorotriazine (MCT) modified to improve its fabric interaction and stability, while histological and immunohistochemical examinations were conducted to determine its safety. The fabrics were subjected to FT-IR, SEM, XRD, TGA, fiberometric, and Zeta potential analysis, while the repellency study was conducted in an olfactometer. Insecticidal monoterpenes and sesquiterpenes were confirmed by GC–MS, and an entrapment efficiency of 94.3% was achieved. The repellent interaction with the fabric was confirmed by the formation of two intense bands at 3277 (O–H) and 1710 cm−1 (C=O), broad diffraction peaks at 17.30° and 38.30–57.10° about a 4.70% increase in average fibre size and a 18.8% decrease in pore size, and lower fibre thermal stability. The surface of the fabric is negatively charged, causing an enhancement in the adsorption and affinity of VnEO by grafting of β-CD/MCT. The dermatological investigation suggests that the oil has no significant toxic effects. In conclusion, the encapsulation and fabric grafting employed are effective and safe for the preparation of a long-lasting repellent fabric.

Abstract Background Numerous bioassay methods have been used to test the efficacy of repellents for ticks, but the comparability of results across different methods has only been evaluated in a single study. Of particular interest are comparisons between bioassays that use artificial containers (in vitro) with those conducted on a human subject (in vivo) for efficacy testing of new potential unregistered active ingredients, which most commonly use in vitro methods. Methods We compared four different bioassay methods and evaluated three ingredients (DEET [N,N-Diethyl-meta-toluamide], peppermint oil and rosemary oil) and a negative control (ethanol) over a 6-h period. Two of the methods tested were in vivo bioassay methods in which the active ingredient was applied to human skin (finger and forearm bioassays), and the other two methods were in vitro methods using artificial containers (jar and petri dish bioassays). All four bioassays were conducted using Ixodes scapularis nymphs. We compared the results using nymphs from two different tick colonies that were derived from I. scapularis collected in the US states of Connecticut and Rhode Island (northern origin) and Oklahoma (southern origin), expecting that ticks of different origin would display differences in host-seeking behavior. Results The results between bioassay methods did not differ significantly, even when comparing those that provide the stimulus of human skin with those that do not. We also found that tick colony source can impact the outcome of repellency bioassays due to differences in movement speed; behavioral differences were incorporated into the assay screening. DEET effectively repelled nymphs for the full 6-h duration of the study. Peppermint oil showed a similar repellent efficacy to DEET during the first hour, but it decreased sharply afterwards. Rosemary oil did not effectively repel nymphs across any of the time points. Conclusions The repellency results did not differ significantly between the four bioassay methods tested. The results also highlight the need to consider the geographic origin of ticks used in repellency bioassays in addition to species and life stage. Finally, our results indicate a limited repellent efficacy of the two essential oils tested, which highlights the need for further studies on the duration of repellency for similar botanically derived active ingredients and for evaluation of formulated products. Graphical Abstract

The repellency of solvent extracts of Calpurnia aurea leaves was evaluated on the maize weevils and the red flour beetles. Nine-cm Whatman number 1 filter paper that is partitioned into treatment, neutral and non-treatment portions was used for the experiment. Each solvent extract treatment was applied at 2.5, 5 and 10% rates. Insects were released in the neutral portion, while the untreated part served as a control. A choice bioassay experimental method that is laid down in a completely randomized design within three replications was used. 5 and 10% rates of the polar solvent extracts of Calpurnia aurea leaves induced significantly (p

Simple Summary: Both field and laboratory studies showed that 0.0125% fipronil bait is repellent against S. invicta workers; therefore, higher concentrations of fipronil should be avoided in fire ant bait production. In future studies evaluating the effectiveness of fire ant baits, we suggest considering the effect of active ingredients and their concentrations on bait acceptance. The red imported fire ant, Solenopsis invicta Buren, is a severe pest with agricultural, ecological, and medical significance. The baiting treatment is one of the main methods to control S. invicta. However, few studies have evaluated the acceptance of fire ant bait. Here, field and laboratory studies were conducted to investigate the foraging behaviors of S. invicta responding to fire ant baits containing different concentrations of active ingredients (fipronil, abamectin, or indoxacarb). Field studies showed that S. invicta transported significantly less 0.0125% fipronil bait than control bait (without toxicant) and 0.0001% fipronil bait. The number of foraging ants significantly decreased with an increase in fipronil concentration. Our previous study showed that S. invicta usually buries the food treated with repellent chemicals, and interestingly, significantly more soil particles were transported into tubes containing 0.0001% fipronil bait than tubes containing control bait or 0.0125% fipronil bait. In addition, S. invicta transported significantly less 0.0005% abamectin bait than control bait, and significantly fewer ants were found in tubes containing 0.0125% abamectin bait than control bait. However, there was no significant difference in bait transport, number of foraging ants, and weight of soil particles relocated in tubes containing different concentrations of indoxacarb bait. In addition, laboratory studies showed that S. invicta transported significantly less 0.0125% fipronil bait than control bait and bait containing abamectin (0.0025% or 0.0125%) or indoxacarb (0.0125% or 0.0625%). In addition, the transport speed for the 0.0125% fipronil bait was the slowest. These results show that specific concentrations of some active ingredients may negatively affect bait acceptance for S. invicta, and should be avoided in fire ant bait production. [ABSTRACT FROM AUTHOR]

Different plant part extracts of cherry laurel [Prunus laurocerasus (Rosaceae)] were investigated for the acaricidal and repellent activity against Polyphagotarsonemus latus (Prostigmata: Tarsonemidae). The leaf, flower, and seed aqueous extracts of cherry laurel were prepared for efficacy bioassays. The tested concentrations of each extract were 1% (volume/volume, v/v), 5% (v/v), 10% (v/v), 20% (v/v) and 30% (weight/volume, w/v). Distilled water and a mixed formulation of 228.6 g/L spiromesifen + 11.4 g/L abamectin were used as negative and positive controls, respectively. It can be concluded that the flower and leaf extract of P. laurocerasus at 30% concentration and the seed extract at 10% or greater concentrations have the potential to control P. latus in the egg stage. Although spiromesifen+abamectin caused extremely low egg mortality (9.5%), all larvae died shortly after hatching (indirect ovicidal effect). In contrast, all adult mites died within 20 hours after spraying. Moreover, the adult mortalities (92%-98%) associated with seed extract at 30% during the experimental period, and the leaf (93.78%) and flower (91.11%) extract at 30% 72-h after exposure were statistically similar to that of spiromesifen+abamectin (100%) application. All extracts at 20% and seed extract at 10% or greater concentrations may also have a great potential for repelling P. latus. [ABSTRACT FROM AUTHOR]