The Tunisian Artemisia Essential Oil for Reducing Contamination of Stored Cereals by Tribolium castaneum

Esencijalna ulja triju vrsta roda Artemisia (A. absinthium L., A. campestris L. i A. herba-alba (Asso)) ispitana su spregnutom tehnikom plinske kromatografije i masene spektrometrije (GC-MS), te je utvrđen njihov mogući insekticidni i repelentni učinak na skladišnog štetnika žitarica Tribolium castaneum (Herbst). Provedeni su in vitro pokusi ispitivanja fumigacijskog i repelentnog učinka. Kemijska karakterizacija esencijalnih ulja pokazala je da u pelinovom ulju prevladavaju biciklični monoterpeni. Ulje pravog pelina (A. absinthium) sadržavalo je najviše bicikličnih monoterpena, bicikloheptana, naftalena i cikloalkena, a ono vrste A. campestris najviše seskviterpena i acikličnih monoterpena. Bijeli pelin (A. herba-alba) imao je najviše p-mentan tipa monoterpena, tetrahidropirana, kumena, tetrahidrofurana, ketona, benzenoidnih spojeva i monocikličnih monoterpena. Ispitivanje fumigacijskog učinka pokazalo je da su tri zasebno primijenjena ulja prouzročila veliki mortalitet štetnika. Najmanju srednju smrtnu dozu (LC50=142,8 μL/L) imalo je ulje bijelog pelina. Ulje vrste A. absinthium imalo je jači i brži repelentni učinak od ostalih vrsta. Mješavina esencijalnih ulja triju vrsta pelina imala je antagonistički učinak u svim ispitanim kombinacijama. Ovaj rad naglašava važnost moguće primjene esencijalnih ulja pelina, naročito vrsta A. herba-alba (bijelog pelina) i A. absinthium, na suzbijanje štetnika na uskladištenim proizvodima.Essential oils of three species of Artemisia genus (A. absinthium L., A. campestris L. and A. herba-alba (Asso)) were analyzed by gas chromatography–mass spectrometry (GC-MS) and their potential insecticidal and repellent activities against the stored grain insect Tribolium castaneum (Herbst) was investigated. Fumigant and repellent activity bioassays were investigated in vitro. Chemical characterisation of essential oils showed that the bicyclic monoterpenes were predominant in all Artemisia essential oils, A. absinthium essential oil having the highest content of bicyclic monoterpenes, bicycloheptanes, naphthalenes and cycloalkenes. A. campestris had the highest content of sesquiterpenoids and acyclic monoterpenoids. A. herba-alba was characterised by the highest amounts of menthane monoterpenoids, oxanes, cumenes, oxolanes, ketones, benzenoids and monocyclic monoterpenes. Fumigant bioassay demonstrated that the three types of oil applied separately caused significant insect mortality. The lowest median lethal dose, LC50=142.8 μL/L, was observed with A. herba-alba. In repellency test, essential oil of A. absinthium was more potent with more rapid action than all other species. The mixture of Artemisia sp. essential oils showed an antagonistic effect in all the tested combinations. This study highlighted an important potential of Artemisia sp. especially A. herba-alba and A. absinthium in the control of the pests of stored products

Toxicity of the active fraction of Pergularia tomentosa and the aggregation pheromone phenylacetonitrile on Schistocerca gregaria fourth-instar nymph: effects on behavior and acetylcholinesterase activity

Chemical insecticides remain the most used approach in locust control although they present a serious menace to human health and the environment. The search for alternative control methods, efficient and environmentally friendly, has become indispensable. The aim of this work is to study the effect of the aggregation pheromone, phenylacetonitrile, alone or in combination with the active fraction of Pergularia tomentosa on Schistocerca gregaria fourth-instar nymph. Toxicity bioassays showed that the combination of phenylacetonitrile with the active fraction of P. tomentosa significantly increased nymph mortality. Results also showed that the aggregation pheromone caused significant mortality especially after 6 hours of exposure. The pheromone also caused neurotoxic effects on S. gregaria nymph due to the disturbance of the acetylcholinesterase activity. We also noted the presence of cannibalism phenomenon. Phenylacetonitrile seems to have an effect on phase ployphenism of S. gregaria imagos that exhibit specific traits to the solitarious phase

Antifeedant and insecticidal properties of Solanum elaeagnifolium extracts on the African Cotton Leafworm

Antifeedant, malformations, and growth inhibition induced by leaves and seeds methanolic extracts of Solanum elaeagnifolium against Spodoptera littoralis were investigated. Seeds and leaves extracts were added to an artificial diet which was found to have an inhibitory effect on the growth of the larvae. The highest growth inhibition was recorded on larvae treated with seeds extract (59.68%) compared to leaves extract (45.17%). The toxicity was demonstrated by a reduction of the weight do to the anti-feeding activity, an elongation of the larval stadiums until development stopping and larval mortality. The seeds extract shows strong antifeedant activity (28.50%) as compared to leaves extract tested (6.64%). The larval mortality was caused by seeds extract (100%) in response to exuviation difficulties. While, the leaves extract caused various degrees of morphogenesis abnormalities in pupae, with mortality rate around 80%. Our results suggest that seeds methanolic extract of S. elaeagnifolium shows an effective insect growth inhibiting and exhibits great promise in suppressing the population of S. littoralis

Fumigant activities of essential oils and their mixtures from cultivated aromatic plants against Spodopteralittoralis (Boisduval, 1833)

The objective of the present study was to investigate the insecticidal activity of essential oils from cultivated aromatic plants and their combinations against larvae of Spodoptera littoralis. Essential oils from Salvia officinalis, Mentha longifolia and Origanum majorana and their mixtures were tested by fumigation. The ability to kill more than 80% was observed in all tested essential oils at 200µL/Lair. In the case of individual essential oils, the LC50 were ranged from the most toxic to the least as fellow: M. longifolia (31.66 μL/L) followed by S. officinalis (42.70 μL/L) and O. majorana (58.28 μL/L). Moreover, the combination of S. officinalis with M. longifolia and with O. majorana might be the two most effectives in controlling the insect than individuals essential oils and the other combinations. The investigation of the efficiency of each essential oil and combination allow us to create potent combinations for the development of powerful eco-friendly control agents

Evaluation of repellent activity and toxicity of three essential oils against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) using a mixture design

Economic damages caused by pest infestation during storage is a major problem in developed and developing countries. Synthetic pesticides have been mainly used to control stored product pests since 1960. Nowadays, appearance of resistance and human health’s risks underline the alternative research needs. Plants essentials oils are recognized as a safe alternative for insecticide applications. The present study was conducted to investigate the insecticidal activity of a number of essential oils from cultivated aromatic plants and their combinations against Tribolium castaneum. Three essential oils and their mixtures were evaluated by fumigation and repellent effectiveness tests against Tribolium castaneum. Bioassays indicated that M. longifolia EO has the most important insecticidal potential as fumigant and repellent. Our results indicated that fumigant and repellent activities of essential oils mixtures can be improved by synergistic and Additive effect. Whereas, some combination exhibited a low insect mortality and repellency regenerated by the antagonistic effect. In our study we underlined the insecticide potential of the essential oils mixture but other studies should be elaborated for a new pesticide elaboration

Insecticidal Activities of Fruit Peel Extracts of Pomegranate (Punica granatum) against the red flour beetle Tribolium castaneum

Aqueous, ethanol and methanol fruit peel extracts of Punica granatum were tested under laboratory conditions for their insecticidal activities against larvae and adults of the red flour beetle, Tribolium castaneum. The beetles were exposed to the different extracts by topical application and ingestion treatment. Highest mortalities were recorded on larvae treated with ethanol extract with mortalities of 72 and 56% for topical application and ingestion treatment respectively. The three extracts exhibited anti-feeding effects (70% > AFI ≥ 50%) against T. castaneum larvae whereas only methanol extract exhibited a low anti-feeding activity (50% > AFI ≥ 20%) against adults. Additionally, only ethanol extract showed repellent activity. Results suggested the presence of toxic active components in the ethanol fruit peel extract acting by mainly ingestion and topical application. The treatment with this botanical insecticide may be promising in protecting stored grains from coleopteran pest infections

Effect of olive leaf extracts on the feeding, growth and metabolism of Spodoptera littoralis. Ben Hamouda, A., Boussadia, O., Bedis, K., Chaieb, I., Laarif, A., and Braham, M. (Tunisia)

In the present study, methanol and acetone crude extracts of olive leaf were investigated for their antifeedant activity, growth and metabolism inhibitory against the cotton leaf worm, Spodoptera littoralis under laboratory conditions. Two feeding tests: leaf discs and artificial diet at three concentrations (0.1, 1 and 10%) of each extract, were implemented in the experiment. Results revealed that the leaf discs bioassay was more effective than the artificial diet bioassay for the antifeedant activity and the weight loss of S. littoralis larvae. Acetone and methanol extracts caused strong antifeedant activity at 10% with 68.33 and 61.44%, respectively. Tests performed on growth generated a very pronounced inhibition of growth gain using leaf disc test for the two extracts and at all tested concentrations. Data indicated that the lowest relative consumption rate (RCR) and the relative growth rate (RGR) were recorded using acetone extract at 10% for leaf discs bioassay (5.88 ± 0.75 and 0.07 ± 0.05 mg/mg/day, respectively). The efficiency of the conversion of ingested food (ECI) and the efficiency of conversion of digested food (ECD) were significantly lowered using methanol extract at 10% in artificial diet bioassay (2.5 ± 0.58 and 2.55 ± 0.6%, respectively). The highest approximate digestibility (AD) of S. littoralis larvae was found in both extracts for the artificial diet bioassay. Moreover, larvae exposed to 10% methanol extract in artificial diet test exhibited a delayed growth rate by 17.7 days, relative to control at the same concentration, compared to 5.7 days noted using acetone extract in leaf disc test. The antifeedant activity, growth and metabolism parameters are appropriate tools in feeding tests and extracts’ activity evaluation. They could provide profound understanding of the choice of the best plant extracts that could be proposed as bioinsecticides in a more environmentfriendly approach

Chemical composition and insecticidal effects of Citrus aurantium essential oil and its powdery formulation against Tuta absoluta. Zarrad, K., Chaieb, I., Ben Hamouda, A., Bouslama, T., and Laarif, A. (Tunisia)

The aim of this research was to investigate the chemical composition and to evaluate the insecticidal activities of the bitter orange Citrus aurantium essential oil and its major compound pure limonene against adults and larvae of the tomato miner Tuta absoluta using contact and fumigation bioassays. Results of chemical analysis of the essential oil using gas chromatography/mass spectrometry (GC-MS) revealed the presence of limonene (87.52%), β-myrcene (1.62%), α-pinene (0.56%) ß-ocimene (0.81%) and ß-pinene (0.61%) as major components. For bioassays, results indicated that both the oil and its major compound were found to be toxic to larvae and adults. In the fumigant assays, median lethal concentrations (LC50) were 10.65 and 37.36 µl/l air respectively for C. aurantium essential oil and pure limonene. In contact toxicity assay, the tomato miner adults were more susceptible to the oil than to its major compound even at the lowest concentration: LD50 values obtained after 48 h were respectively 0.21 and 0.73 µl. When insects were treated with the essential oil and its aromatized clay powder, significant differences in insect mortality were recorded depending on exposure time. The aromatized clay powder was more toxic (LT50 = 101.8 h) than the pure essential oil (LT50 = 146.32 h). Hence, bitter essential oil was found to be toxic for T. absoluta, and the clay powder could be used to stabilize the essential oil to increase its efficacy and possibly will be used as source of new eco-friendly insecticidal compounds