Origanum genus belonging to the Lamiaceae family is aromatic and medicinal plant. It has been used in many countries for medicinal and pharmaceutical purpose. Aerial part of the Origanum syriacum L. was dried at shade. The essential oil was generated by steam distillation and compounds were identified by GC-MS analysis. γ-terpinene (26.7%), thymol (26.6%) and carvacrol (22.9%) was detected as the mail constituents. The essential oil was tested for insecticidal activity against adult of Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) using fumigation method. Essential oil revealed the excellent fumigant effect on R. dominica adults with a median lethal concentration (LC50) value of 0.124 µl/insect and 0.107 µl/insect for 48 h and 72 h respectively. LC50 values of S. oryzae were found as 0.173 µl/insect and 0.135 µl/insect for 48 h and 72 h respectively. As a result, essential oil of O. syriacum has a potency to be a natural insecticide.

The search for new plant natural products with insecticidal properties to control insect pests in agriculture has gained relevance in the past decades. The aim of the study was to investigate the insecticidal activity of extracts derived from flower, leaf, and stem of three Hypericum species (Hypericum heterophyllum, Hypericum perforatum, Hypericum scabrum) against the adults of three important stored grain insect pests namely; Sitophilus oryzae (Curculionidae), Rhyzopertha dominica (Bostrichidae) and Tribolium confusum (Tenebrionidae). The insects were incubated with the food under 10% concentration of Hypericum extracts and the mortality was recorded after 24, 48 and 72 h of exposure. The extracts of the Hypericum species and exposure time were found to have statistically significant effective against the three insect pests. After 72 h exposure, the mortality ranged from 4.3 to 94.1 % for all insects. Among tested insects, R. dominica was more susceptible than T. confusum and S. oryzae. Although desirable insecticidal effect against the insects were recorded from all the three Hypericum species, the leaf extract of H. perforatum was more effective on R. dominica, while the flower and stem of H. scabrum displayed high toxic effect on T. confusum and S. oryzae, respectively. The leaf extracts, of H. perforatum, in particular, may be used as source of new potential botanical insecticides against R. dominica in stored grains.

The insecticidal potential of tea tree oil formulations was tested for contact and stomach poison toxicities against various stages of the Spodoptera littoralis ((Boisduval, 1883) (Lepidoptera: Noctuidae) larvae under laboratory conditions. The study was carried out at Yozgat Bozok University Faculty of Agriculture between 2020 and 2021. In the contact toxicity test, the formulations were tested at different stages of larvae by topical application. Among the tested formulations, TTO (100%), F14 (91.72%), and F15 (89.20%) formulations caused the highest mortality in the S. littoralis 3rd stage larvae after 72 h. Dose-response bioassay with the most promising formulations (TTO, F14 and F15) revealed that LD50 values were 0.016, 0.046, and 0.076 μg/larvae for TTO, F14, and F15, respectively. The stomach poison effects of the formulations were tested by applying a 0.16 μg/cm$^{2}$ dose to lettuce leaf discs. The F17 and F18 formulations produced the highest mortality with mortality rates of 75% and 65% after 10 days of incubation, respectively. The calculated LC$_{50}$ values for these formulations were 0.027 and 0.042 μg/cm$^{2}$ for F17 and F18 formulations after 10 days of incubation, respectively. These results revealed that tea tree oil and its main components containing formulations have the potential in controlling this destructive lepidopteran pest species.

Bu çalışmada, biberiye (Rosmarinus officinalis L.) ekstraktlarının depolanmış önemli bir tahıl olan buğday (Triticum aestivum L.) tohumlarının çimlenmesi üzerindeki fitotoksik etkisi ve tahıl zararlıları olan Sitophilus oryzae (L.) ve Rhyzopertha dominica (F.) türleri üzerindeki insektisidal aktiviteleri araştırılmıştır. Biberiye bitkisinin yaprak kısımlarından ekstrakt elde edilmesi için farklı çözücüler (etanol, metanol ve aseton) kullanılmış ve en yüksek ekstrakt verimi %10.5 ile aseton çözücüsünden elde edilmiştir. Aseton ekstraktının 250 µg/ml (A250) ve 500 (A500) µg/ml konsantrasyonları buğday tohumlarının çimlenmesinde en yüksek değere (sırasıyla %96.7 ve %95.6) sahip olurken, kontrol (%98.9) uygulamaları ile aralarında istatistiki fark olmadığı tespit edilmiştir. Hatta A250 ekstraktı (85±0.6 mg) ile kontrol1 (92±0.6 mg) uygulamalarında istatistiki olarak en yüksek bitki taze ağırlığı saptanmıştır. Tüm ekstraktlar buğday bitkisinin radikula ve plumula uzunlukları üzerinde negatif etkiye sahip olmuştur. Biberiye ekstraktlarının artan konsantrasyonları tüm parametrelerde negatif etkiyi artırmıştır. Ayrıca ekstrakların depo tahıl zararlısı türler üzerindeki insektisidal etkisi incelendiğinde, 72 saat sonunda en yüksek değer R. dominca için aseton ekstrakında (%68.33), S. oryzae için ise etanol ekstrakında (%58.33) bulunmuştur. Sonuç olarak, biberiye ekstraklarının depolanmış tahıl zararlılarının mücadelesinde kullanılabileceği tartışılmıştır.

Medicinal and aromatic plants have popular recently to investigate their usability as natural resources in many areas due to their superior biological activity properties. Hypericum genus contained important medicinal plant species known worldwide. In this study, the ethanol extracts from different plant parts (flower, leaf and stem) of three Hypericum perforatum, Hypericum heterophyllum, Hypericum scabrum were screened for their toxicity against adults of Rhyzopertha dominica (Coleoptera: Bostrichidae), an important insect of stored grains in many regions of the world. Insecticidal activity was analysed at 10 % concentration of ethanol extracts, and measurements were taken at three different exposure times (24, 48 and 72 hours). Considering the factors analyzed on this insect, Hypericum species, plant part, exposure time as well as the interaction of Hypericum species and plant part displayed a statistically significant effect. The mortality values of extracts from H. perforatum, H. heterophyllum and H. scabrum varied from 44.8 % to 88.9 %, 26.0 to 78.8 %, 26.1 % to 50.3 % for adult of R. dominca, respectively, after 72 h. H. perforatum showed a stronger effect than other species. Among plant parts, the leaf showed superior mortality on this insect. In addition, the mortality rate increased with increasing exposure time. According to the interaction between Hypericum species and the plant part, the leaf of H. perforatum (79.4 %) displayed the strongest mortality, followed by the leaf of H. heterophyllum (70.6 %). After 72 hours, the highest mortality was recorded in the leaf parts of H. perforatum. The current results showed that the extracts, in particular, the leaf extracts of H. perforatum and H. heterophyllum, may be evaluated as a new natural potential product of plant-derived insecticide because of its high mortality impact against R. dominica.

Bu çalışmada, Reseda lutea L. (Resedaceae), Salvia absconditiflora Greuter & Burdet. (Lamiaceae), Thymus leucostomus Hausskn. & Velen. (Lamiaceae), Chorispora purpurascens (Banks & Sol.) Eig (Brassicaceae), Isatis floribunda Boiss. ex Bornm. (Brassicaceae), Linum tenuifolium L. (Linaceae) bitkilerinden elde edilen methanol ekstraktlarının Tribolium confusum Duv. (Col.: Tenebrionidae) ve Rhyzopertha dominica F. (Col.: Bostrichidae) üzerindeki toksik etkileri laboratuvar koşullarında test edilmiştir. Bitkilerden elde edilen methanol ekstraktları zararlıların erginlerine micro-aplicator yardımıyla uygulanmıştır. Yapılan tek doz (%10 (w/v)) etki çalışması sonucunda T. confusum (%23,17) ve R. dominica (%18,35)‘ya karşı en yüksek kontakt toksisiteyi C. purpurascens bitkisinden elde edilen ekstrakt göstermiştir.