Comparative Bioefficacy of Different Citrus Peel Extracts as Grain Protectant Against Callosobruchus chinensis, Trogoderma granarium and Tribolium castaneum
2 Abstract: Efficacy of essential oils extracted from peel of various citrus species; Citrus reticulata, Citrus sinensis, Citrus paradisi and Citrus grandis were determined against the adults of Callosobruchus chinensis and Tribolium castaneum as well as against the larvae of Trogoderma granarium in order to find out safe alternatives of high toxics. Four concentrations of each oil; 2%, 4%, 6% and 8% were assayed for their insecticidal activity after exposure durations of 24, 48, 120 and 168 h. The results revealed that the essential oil vapors showed variable toxicity to insects depending on concentration and exposure duration. Efficacy increased as the exposure time and concentration were increased for all insects. All the oils were found to be very successful against adults of C. chinensis. Out of which, the oil of C. sinensis was the best against C. chinensis even at lower concentrations; LD , LD and LD values were 3.49%, 4.70% and 5.91% after 72-h 50 70 90
Insecticidal properties of citrus oils against Culex pipiens and Musca domestica.
Peel oils of lemon, grapefruit and navel orange were tested for insecticidal activities against larvae and adults of Culex pipiens and Musca domestica. Lemon peel oil was the most effective against larvae and adults of C. pipiens. Grapefruit peel oil was more toxic to adults of M. domestica while lemon oil, was more toxic Musca larvae. On the other hand, the orange peel oil was the least effective against larvae and adults of both species. The toxicity of oils applied to larval stages was extended to pupal and adult stages. C. pipiens adults appeared with paralyzed legs, while M domestica adults appeared normal. The weights of pupae treated as larvae were generally less than that of the control. All oils produced deleterious effects on fecundity of survivors of sublethal doses. The effect was obviously recorded in treated adults. Treatment of Culex & Musca with oils caused serious latent effect.
Effect of cutting management and nitrogen levels on biomass production and proximate quality of barley (Hordeum vulgare) in saline soil
A field experiment was conducted during the winter (rabi) seasons of 1997–1998 to 1999–2000 on an alluvial loamy sand saline soil at Hisar, to find out the effect of cutting management and nitrogen levels on biomass production and proximate quality of barley (Hordeum vulgare L). Dry forage yield of barley was 6.3% higher when harvested once at 50% heading compared with 2 cuttings at 60 days of growth and 50% heading. The total biomass was 3.8% higher when harvested for grain purpose compared to the treatment in which the crop was first harvested for forage at 60 days and subsequently left for grain purpose. However, no significant differences were observed in the yield equivalents of barley grown for grain purpose or green forage and grain. Application of N significantly increased the yield from 22.5 q/ha with 60 kg N/ha to 29.3 q/ha with 80 kg N/ha. The protein and mineral matter contents were higher in grains (9.2 and 4.7%) and fodder (5.3 and 10.3%) harvested at the early stages than 9.0 and 4.6% in grain; and 4.9 and 9.8% in fodder at the late stage. However, the fibre and lignin contents were more in fodder harvested at later stages. With increasing levels of N application, the mineral matter remained unaffected, while the crude protein and lignin contents increased and fibre decreased in both fodder as well as grain.