Toxicity and sublethal effects of emamectin benzoate, novaluron and diflubenzuron were evaluated against the 2 nd instar larvae of cotton leafworm (CLW). The joint toxic action of emamectin benzoate with novaluron or diflubenzuron was carried out. Emamectin benzoate (LC 50 = 0.014 mg L-1) was 264.3 and 5707.1 times more toxic than novaluron (LC 50 = 3.7 mg L-1) and diflubenzuron (LC 50 = 79.9 mg L-1), respectively. Novaluron was approximately 21.6 times more toxic than diflubenzuron. After 24 hrs of exposure, all mixtures of emamectin benzoate (at LC 10 or LC 25) with novaluron or diflubenzuron (at LC 10 or LC 25) resulted in antagonistic effects with co-toxicity factors (CTFs) ranged between-25 to-700 except the mixture of emamectin benzoate at LC 10 with novaluron at LC 10 (CTF = 60). Mixtures of emamectin benzoate at LC 10 with novaluron at LC 10 and emamectin benzoate at LC 25 with novaluron at LC 25 resulted in potentiating effects after 48, 72 and 96 hrs of exposure. On the other hand, all mixtures of emamectin benzoate with diflubenzuron resulted in antagonistic effects. Emamectin benzoate, novaluron and diflubenzuron at the two sublethal concentrations reduced average larval weight, average time to the pupation, %pupation, pupal mean weight and %adult emergence compared to control. Results of this study verified the lethal and sublethal effects of emamectin benzoate, novaluron and diflubenzuron on the larval stage of S. littoralis, which negatively affect some biological parameters and insect population can be negatively affected. Emamectin benzoate, novaluron and diflubenzuron can be used for S. littoralis control and in resistance management programs, because their mode of action is different from pyrethroid, carbamate and organophosphate insecticides.
Field studies were conducted during 2015 and 2016 cotton growing seasons, at AbouElmatameer, El-Behira Governorate to evaluate certain insecticide sequences in controlling two cotton bollworms pink bollworm (PBW), Pectinophora gossypiella, (Saund) and spiny bollworm (SPW), Earias insulana, (Boisd.) The side effects of all insecticide sequences on the lady beetle, Coccinella undecimpunctata was also determined. During 2015 season, sequence 2 (Dursban ® , Rado-X ® , Radiant ® , Cothrin ®) and sequence 6 (Dursban ® , Rado-X ® , Radiant ® , Proclaim ®) achieved the highest efficacy against PBW, gave general mean reduction percentages 81.4 and 83.5%, respectively. In season 2016, sequence 6 revealed the highest efficacy where the general mean reduction percentage was 83.3%. Sequences 6 induced the highest reduction percentages in cotton bolls infested by SBW in 2015 and 2016 seasons, with general mean reduction percentages 84.0 and 82.3%, respectively. Sequence 4 (Cothrin ® , Radiant ® , Rado-X ® , Dursban ®) achieved the least efficacy against PBW and SBW in both seasons 2015 and 2016. Sequence 6 proved to be the least toxic on C. undecimpunctata. On the other hand, all other sequences were comparable in there effects on C. undecimpunctata in both seasons.
This study was carried out during the two consecutive seasons of 2012 and 2013 in shade house for Plant Production Dept. Fac. Environ. Agri. Sci. Suez Canal Univ. Egypt. Two citrus six-month-old uniform seedling citrus rootstocks namely: Sour orange and Volkamer lemon transferred into black plastic tube PVC (15 cm diameter x 40 cm depth) filled with 2kg growth media mixture of sand soil and peat moss (4:1 by volume) and irrigated using the tap water at 14 days before run treatments. These seedlings were subjected to three different irrigation saline water levels (tap water 700 "control", 2000, and 3000 ppm) to determine the effects of water salt level on growth parameters, chemical compositions, leaf total pigments and proline. The results obtained showed that Volkamer lemon seedlings had the greatest leaf and root biomass, photosynthetic pigments, proline, leaf k content and area of root vascular bundle and had the lowest values leaf N, Cl and Na content, thickness of root cortex, thickness of mesophyll tissue and leaf blade, while Sour orange seedlings were on the contrary. On the other hand, irrigation with the saline water caused decrease the all vegetative growth parameters, plant photosynthetic pigments and area of root vascular cylinder, while increased the leaf N, Cl and Na content, leaf proline concentration and thickness of root cortex, thickness of mesophyll tissue and leaf blade. Finally, vegetative growth parameters, leaf mineral and leaf total pigments analysis and anatomy features for root and leaf blade indicated that Volkamer lemon rootstock is more tolerant to salinity of irrigation water.
Insecticidal activity and sublethal effects of white kidney bean and soybean lectins compared to Bacillus thuringiensis var. kurstaki were evaluated against pink bollworm (PBW), Pectinophora gossypiella (Saunders). The in vivo effects of these lectins on the total proteases and αamylase activities of PBW were also carried out. Results revealed that, B. thuringiensis (LC50 = 61.7 and 36.1 µg / g diet) was approximately 4.7 and 4.8 times more toxic than kidney bean lectins (LC50 = 289.2 and 175.0 µg / g diet) and 2.2 times more toxic than soybean lectins (LC50 = 134.3 and 81.2 µg / g diet) after 5 and 6 days of treatment on the 2 nd instar larvae. The LC25 equivalent concentration of B. thuringiensis and soybean lectins achieved the highest reduction of larval weight (11.9 and 13.0 mg / larva compared to 27.1 mg / larva in control) after 9 days of treatment. While kidney bean and soybean lectins at LC10 and LC25 increased the average time to pupation of PBW, B. thuringiensis at LC25 decreased the average time to pupation compared to control. All treatments significantly decreased the pupal mean weight and adult emergence rates compared to control. Kidney bean lectins, soybean lectins and B. thuringiensis at LC25 reduced the average number of eggs laid / female (fecundity) to 35.2, 31.5 and 34.5, respectively, compared to 89.0 in control. In addition, %egg hatch (fertility) significantly decreased to 53.8, 51.7 and 49.1% in kidney bean lectins, soybean lectins and B. thuringiensis LC25 treatments compared to 93.0% in control. Kidney bean and soybean lectins inhibited the activity of total proteases and α-amylase. Results of the present study suggest that kidney bean and soybean lectins can be used as suitable alternatives for B. thuringiensis in integrated management programs of pink bollworm.
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