Effect of Biopesticides Applied Separately or Together on Nutritional Indices of the Rice Leaffolder Cnaphalocrocis medinalis (original) (raw)
Related papers
Insects
In the present work, we evaluated the insecticidal activity of Bacillus thuringiensis (Bt) strains on Euprosterna elaeasa as an alternative for the organophosphate insecticide use in oil palm plantations in the Americas. The toxic effects of four Bt-strains (HD-1 var. kurstaki, SA-12 var. kurstaki, ABTS-1857 var. aizawai, and GC-91 var. aizawai) were evaluated against E. elaeasa caterpillars for toxicity, survival, anti-feeding, and mortality in field-controlled conditions. The Bt-strains, ABTS-1857 var. aizawai (LC50 = 0.84 mg mL−1), GC-91 var. aizawai (LC50 = 1.13 mg mL−1), and HD-1 var. kurstaki (LC50 = 1.25 mg mL−1), were the most toxic to E. elaeasa. The caterpillar survival was 99% without exposure to Bt-strains, and decreased to 52–23% in insects treated with the LC50 and 10–1% in insects exposed to LC90 after 48 h. Furthermore, Bt-strains decreased significantly the consumption of oil palm leaves of E. elaeasa 3 h after exposure. Mortality of E. elaeasa caterpillars caused b...
Egyptian clover (Trifolium alexandrinum) is one of the most important crops in Egypt and consider as one of the major sources of food for domestic animals and birds. This crop attacked by many pests all over its life stage especially cotton leafworm, Spodoptera littoralis (Boisd.) which is a predominant and serious pest. The larval stage is the major enemy that is because it acts as the main notorious defoliator that attack not only Egyptian clover but also several field crops, vegetables and deciduous fruits. Occurrence of tolerant and resistant strains of insect pests have been developed as a result of continued use of synthetic insecticides. Considerable efforts are being made worldwide to find safer, biodegradable substitutes for these synthetic insecticides. Bioinsecticides received a great attention as a hope for the future of insect control that gave a promising effect against S. littoralis (Sannino et al., 2001 and Raslan, 2002) with low toxicity to mammals and some predators (Duffie et al., 1998). Also, entomopathogenic fungi, Metarhizium anisopliae (Metsch.) Sorok, is known to possess insecticidal and antifeedant properties against some lepidopteran pests (Kim et al., 2002). Carbohydrates are of vital importance since they can be utilized by the insect body for production of energy or conversion to lipids or proteins. Metabolism of carbohydrates is controlled mainly by trehalase, amylase and invertase enzymes that play a principle role in the digestion and utilization of carbohydrates by insects (Wyatt, 1967 and Wigglesworth, 1972). The objective of this work was planned to evaluate the toxicity of three bioinsecticides (two bactericide and a fungicide) as well as a mineral oil KZ oil against S. littoralis under laboratory and field conditions. Further studies were made to estimate their biological and biochemical changes in S. littoralis larvae as affected by the precedent treatments.
Diamondback moth (DBM), Plutella xylostella (L.), remains a major pest of brassica crops worldwide. Chemical control of this pest remains difficult due to the rapid development of resistance to insecticides and to their effect on natural enemies. The objective of this study was to assess the toxicity of Bacillus thuringiensis (Bt), neem oil and methamidophos on larvae of P. xylostella under laboratory conditions. Leaf-dip bioassay for DBM larvae was used to assess mortality. For each treatment, three doses (low, medium and high) were applied on cabbage leaves and presented to third instar larvae. Larval mortality was performed every 24 hours for a period of eight days. The application of the three dosages of Biobit was more effective against P. xylostella larvae when compared to the other treatments. However, there was no significant difference in larval mortality when all three doses of Biobit were tested compared to the control. Methamidophos was the least toxic treatments with hi...
TOXIC EFFECT OF FOUR PLANTS AT THREE DIFFERENT FORMULATIONS AGAINST SOME STORED GRAIN INSECTS
In the present study, four plants namely, cinnamon, thyme, mint and ginger prepared in the three different formulation forms, powders, oils and extracts compared with the malathion insecticide 1% dust which included in this study as a standard reference. The main aims of this study was to compare the efficiency of the formulation forms for protecting maize grains against rice weevil Sitphilus oryzae (L.) and red flour beetle Tribolium castaneum (Herbst) adults . The results showed that the mortality percentages increased with increasing the concentration and period of exposure with all formulation forms used and insecticide against the two tested insects. The results revealed that the number of emerged offspring decreased with increasing the concentration with all formulation forms used and insecticide (malathion dust 1% w/w). In general, the plant extracts were the most effective formulation forms on the two tested insects specially the plant petroleum-ether extracts followed by plant oils and powders. The plant extracts gave results nearly equal that of chemical insecticide (malathion) with the study criteria, mortality percentages, reduction in F1 progeny and the grain loss of weight. All treatments had significantly desired effects on the percentages of maize grain weight loss compared to the untreated. Results also indicated that T. castaneum was less sensitive for all treatments used than S. oryzae. It could be recommended to use these plant formulations as protects stored maize grain against insects infesting specially plant extracts used at the highest concentrations.