Natural insecticides from native plants of the Mediterranean basin and their activity for the control of the date moth Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae)

The present work aims at evaluating the insecticidal activity of T. algeriensis and T. hyemalis (Lamiaceae) essential oils against different stages of Eceratoniae ceratoniae Zeller (Lepidoptera: Pyralidae) in controlled conditions. Essential oil vapours were isolated by hydrodistillation and analysed by gas chromatography-mass spectrometry technique (GC-MS). Camphor (37.29%), 1,8-cineole (11.12%), camphene (7.81%), myrcene (7.13%) and borneol (5.54%) were obtained as major compounds in the essential oil of T. algeriensis, while the main essential oil compounds of T. hyemalis were 1,8-cineole (34.17%), camphor (8.33%) and camphene (7.11%). Ovicidal activity of oils was studied by topical application, while the adulticidal and larvicidal activities were assessed by fumigation and ingestion. The results revealed that T. hyemalis oil was more effective as compared to T. algeriensis. The exposure to T. hyemalis vapour caused 0% of hatching rate at the concentration of 2.5 mg/ml, while at the same concentration, the hatching rate was 15% when eggs were exposed to T. algeriensis oil. The adulticidal activity of both oils decreased with the increase in concentration or exposure time. The corresponding LC50 values were found to be 0.11 and 0.19 mg/ml respectively for T. hyemalis and T. algeriensis. Young larvae L1 seemed to be more resistant to both essential oils in the antifeedant bioassay (LC50 = 2.75 mg/ml for T. hyemalis and 5.78 mg/ml for T. algeriensis). Overall, this work showed the efficacy of essential oils from plants of Mediterranean origin that could be used as an alternative to synthetic insecticides for the managing of E. ceratoniae

Investigation on combustion characteristics and emissions of biogas/hydrogen blends in gas turbine combustors

In the present work, numerical investigations are performed to study the combustion characteristics of biogas fuel blended with hydrogen at various compositions for a non-premixed swirling flame in a can-type gas turbine combustor. The amount of hydrogen enrichment varies from 0 to 50% by volume. A numerical approach using the non-premixed flamelet model, turbulent standard (k–ε) model, and P-1 radiation model was adopted for simulating the can-type combustor power at a fixed operating power of 60 kW. The steady laminar flamelet model was used to analyze the effect of hydrogen enrichment, global equivalence ratio with different swirl numbers on a stable flame operation, temperature distribution and contours, velocity streamline contours, NO emissions, and species concentrations. The results indicate that hydrogen enrichment and the variation of the equivalence ratio and the swirl numbers significantly impacted the flame macrostructure. Hydrogen enrichment in the fuel intensifi combustion, leading to higher flame temperature and wider flammability than bure biogas. Maximum NO emissions in the outlet chamber have been dropped by 43 and 78 (ppm @15 % by volume of O 2) for the biogas and biogas-50% H 2, respectively, due to the reduced flame temperature leading to reduction in thermal NOx formation with reduction equivalence ratio from 0.5 to 0.2. The flame temperature and NO emissions at ϕ=0.2 with a high rate of hydrogen (50% H 2) are close to the results of pure biogas (0% H 2) at the same equivalence ratio. The results show that CO and CO 2 emissions decrease with increasing hydrogen addition and decreasing the equivalence ratio; due to a decrease in the amount of carbon, the cooling effect, and an increase in the OH concentration