Comparative studies of semi-artificial diets on the biology and the bionomics of the European corn borer, Ostrinia nubilalis Hübner (Or.: Lepidoptera, Fam. : Pyralidae)

Comparative studies of two semi-artificial diets (S.A.1 and S.A.2) as well as a natural corn diet were studied on the biology and bionomics of the European corn borer, Ostrinia nubilalis under laboratory conditions. The insect was successfully mass reared for ten successive generations at the conditions of 27 +/- 2 degrees C, 60-80% R.H. in addition of photoperiod of 6:18 (L: D) for larvae and 12:12 (L: D) for the other stages, respectively. Along ten successive generations, there were no significant differences between the larval periods for both artificial diets. The S.A.1 induced the shortest larval period (22.5 days) compared to the artificial diet S.A.2 (24 days) and the natural diet (25 days). Meanwhile, the rearing larvae on the natural diet revealed means of pre-pupal and pupal periods of 2 and 8 days which decreased to 2 and 6.5 days in both artificial diets (S.A.1 and S.A.2), respectively. However, the pupal weight and length were insignificantly increased in S.A.1 (121.7 g and 1.7 cm) than that in the natural diet (115.5 g and 1.8 cm) and were in the artificial diet S.A.2 (101.2 g and 1.7 cm), respectively. Moth longevity (pre-oviposition, oviposition and post-oviposition periods), was affected to a certain extent by the larval diets. The maximal moth longevity was recorded (15 days) for larva reared on the natural diets. On the other hand, the shortest period was observed (10.5 days) for the moth longevity in S.A.1. The artificial diet S.A.2 showed the moth longevity (13 days). The longest oviposition period was recorded (10 days) in the natural diet, while it was only (6.5 days) in the artificial diet S.A.1 compared with (8 days) in the artificial diet S.A.2. The number of the deposited eggs/female throughout the 10 successive generations was (400) in the natural diet, while the artificial diet S.A.1 revealed the least number (304.4) versus (358.2) in the artificial diet S.A.2. On the other hand, the number of hatched eggs/female were (320) in the natural diet, versus (310.9 and 256.5) in the artificial diet S.A.2 and S.A.1, consequently. The highest mean of hatchability percent was 86.93% resulted in the artificial diet S.A.2 compared to. 83.92% in the artificial diet S.A.1 and 80% in the natural diet. It was observed that the shortest total generation period found (41.5) days in the artificial diet S.A.1 while it was (50 and 45.5)days in the natural diet and the artificial diet S.A.2, consequently. The results declared that the artificial diet S.A.1 is a suitable artificial diet as it is considered mass rearing of the European corn borer, Ostrinia nubilalis Hub.

Biological performance of quercetin on the cotton leaf-worm larvae, Spodoptera littoralis Boisd. (Lep., Noctuidae) and prevailing natural enemies in the Egyptian cotton fields

The Egyptian cotton (Gossypium barbadense L.) accounts for 65 % of the world production of long stable cultivars. Taking into consideration the competition of other cotton producing countries, it should be of great importance to control pests, which attack the cotton plants to improve the yield and its quality. The main objective of this study is to develop new approaches for the management of the cotton leafworm Spodoptera littoralis Boisd. within an IPM program, that include synthetic insecticides rationalization, and maximiziation the role of the biological control agents. Sunflower plants Helianthus annuus (Asterales: Asteraceae) raised in rows surrounding plots of cotton were used as trap plants to attract some biological agents, which subsequently lead to check the build-up of the cotton leafworm population. This scientific phenomenon was attributed to the main chemical constituent of sunflower plants, which has been proved to be the polyhydroxy flavone "quercetin". Field data of the two successive seasons 2004 and 2005 revealed that: (a) the total number of insect predators, Coccinella undecimpunctata, Paederus alfierli, Chrysopa vulgaris, Orius laevigatus, Scymnus synacus, and true spiders in the cotton plots surrounded by either one or two rows of sunflower plants significantly exceeded the corresponding numbers in the cotton plots without sunflower plants., (b) the least number of cotton leafworm Spodoptera littorolis larvae infestation was recorded simultaneously in the cotton plots surrounded by sunflower plants. Moreover, laboratory studies assured the antifeeding properties of quercetin against the 4th instar larvae of Spodoptera littoralis. Quercetin at a concentration rate of 4000 ppm, showed abnormal behaviour represented in feeding stop, growth inhibition and development retardation. Deformation of pupae, moths, and reduction up to 50% in egg laying was also noticed after quercetin application to the larvae.

Joint action of quercetin with four insecticides on the cotton leaf-worm larvae, Spodoptera littoralis Boisd. (Lep. : Noctuidae) in Egypt

The naturally occurring phytoncidal chemical component of some plant- species are responsible for controlling and/or repelling insects from host plants. The use of natural products, readily available in the environment, to control the cotton leafworm, could be of help in reducing the need for applying the synthetic conventional insecticides . Moreover, crude vegetable oils application is quite safer to the non targets and the environment. The use of sex attractant pheromones as predicative tools to forecast pest population and their potential damage levels in specific crops, has significantly been limited because sex attractants are usually directed to one sex only. Thus, identification of plant constituents that attract S. littoralis Boisd. adults, especially females, and that directly affect their feeding or reproductive behaviour, would greatly expand opportunities for manipulation of the biological and environmental events that prevent the establishment, development, and dispersal of the insect-pest under study. Extracted Volatiles from certain parts of cotton plants, attracted both sexes of the cotton leafworm moths instead of attracting one sex only as the pheromones do. Plant flavonoids have been shown by many investigators to have an effect on insect behaviour, growth, and development. Quercetin is one of many bioflavonoids that exists in several fruits and vegetables. The Aim of the present work is to study in vivo the biochemical mode of action of quercetin as a synergist in combination with insecticides. The present results proved the synergistic effect of quercetin when combined with four insecticides, namely, profenofos (organophosphates), deltamethrin (pyrethroid), and tebufenozide et hexaflumuron as insect growth regulators against the studied insect-pest. Quercetin role as a synergist might be attributed to its ability to inhibit certain active oxidases, which may be responsible for in vivo detoxification of the intact insecticides when applied to insect larvae, through glutathione-S-transferase.

Abamectin, pymetrozine and azadirachtin sequence as a unique solution to control the leafminer Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) infesting garden beans (Phaseolus vulgaris L.) in Egypt

Field trails were conducted to determine the performance of three different sequences as a unique solution for the control of the leaf miner Liriomyza trifolii (Burgess) (Diptera: Agromyzidae) infesting garden beans (Phaseolus vulgaris L.) during the two successive seasons of 2004 and 2005. Furthermore, during the evaluation period, the side effect against the ectoparasite Diglyphus isaea (Walker) (Hymenoptera: Eulophidae) was put into consideration. Meanwhile, the comparative evaluation of the pesticides alone showed that abamectin and azadirachtin were highly effective against Liriomyza trifolii, while carbosulfan, pymetrozine and thiamethoxam provided to be of a moderate effect. Moreover, carbosulfan showed harmful effect to the larvae of the ectoparasite Diglyphus isaea (Walker), while abamectin and azadirachtin gave a moderate effect. Thiamethoxam and the the detergent (Masrol 410) had slight effect in this respect. The highly effective sequence among the sequences was abamectin, pymetrozine and azadirachtin, against Liriomyza trifolii (Burgess), with slight harmful effect on Diglyphus isaea (Walker). However the sequence of azadirachtin, pymetrozine and abamectin had a moderate effect on Liriomyza trifolii (Burgess) and exhibited a slight toxic effect on Diglyphus isaea (Walker). In contrast, the sequence of carbosulfan, thiamethoxam and pymetrozine was the least effective and represented a slight effect on Diglyphus isaea (Walker). From this study, it was concluded that abamectin, pymetrozine and azadirachtin sequence has proved to be a unique solution for the control of the leaf miner Liriomyza trifolii (Burgess) infesting garden beans (Phaseolus vulgaris L.) in Egypt.