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1

Effect of sowing dates on the populations of three major insect pests and associated natural enemies throughout the growth stages of maize plants

100%
Mahmoud H. H., Abd El-Rahman S. F., Naroz M. H., Ahmed S. S.
Polish Journal of Entomology
|
2021
|
tom 90
|
nr 3
In Egypt, maize is an important crop that is attacked by various pests. In the present study, the effect of maize planting dates on the populations of insect pests and their natural enemies were investigated throughout the growth stages of maize plants. The maize planting dates were at the beginning of May, Jun, and July in the 2019 season and were repeated in the 2020 season. Samples were collected weekly to determine the populations of the insect pests, Limothrips cerealium (Haliday, 1836), Rhopalosiphum maidis (Fitch, 1856), and Sesamia cretica Lederer, 1857 and their natural predators. For the first sowing date, the infestation percentage of L. cerealium and S. cretica were most substantial, especially in the seedling and precorn formation stages. For the third sowing date, the number of R. maidis was most substantial, especially in the corn formation stage. Three predators were associated with these insect species; of these predators, Coccinella undecimpunctata (Linnaeus, 1758), Scymnus interruptus (Goeze, 1777), and Chrysoperla carnea (Stephens, 1836) were observed at the highest numbers during all sowing dates. A highly significant correlation existed between populations of S. interruptus and the three insects across the two seasons. Data suggest that the percentage of thrips, aphids, and stem borers infestations can be minimized by planting maize varieties in June.
2

Toxicological, biological and biochemical effects of two nanocomposites on cotton leaf worm, Spodoptera littoralis (Boisduval, 1833)

100%
Abd El-Rahman S. F., Ahmed S. S., Abdel Kader M.
Polish Journal of Entomology
|
2020
|
tom 89
|
nr 2
Cotton leaf worm, Spodoptera littoralis (Boisduval, 1833), is one of the most dangerous pests in Egypt, causing economically significant losses of different crops. The present study was aimed to evaluate toxicological, biological and biochemical effects of two nanocomposites, Silver (Ag) and graphene oxide (GO) nanomaterials over magnesium chlorophillin (Mg-Chl/Ag and Mg-Chl/GO) at three concentrations (1, 10, 100 ml/L) against 2nd instar larvae of S. littoralis. The results showed that larval mortality rate was positively correlated with the increase of concentrations of the tested nanocomposites and time after exposure. The mortality rate in nanographene oxide composite were higher than nano silver. LC50 (lethal concentration of 50% of a group of test larvae) values were 10.27 and 16.14 mg/L at Mg-Chl/Ag and Mg-Chl/GO compound at 2 h exposure to light. Some biological aspects of S. littoralis resulted from the treated 2nd instars larvae with two nanocomposites were recorded. Larval, pupal durations, pupation, adult emergence rate and pupal weight were significantly lower in all concentrations compared to untreated larvae. All tested samples showed decrease in total carbohydrates, total proteins and total lipids. Obtained results suggest that using silver and graphene oxide nanomaterials over the magnesium chlorophillin would be a useful component for controlling S. littoralis.
3

Seasonal abundance of the most important insect pests of maize and their natural enemies in Egypt

100%
Mahmoud H. H., Abd El-Rahman S. F., Abd El-Moez Mahbob M., Ahmed S. S.
Polish Journal of Entomology
|
2021
|
tom 90
|
nr 1
The experiment was conducted to study the seasonal abundance of the most important insect pests of maize and its relation with natural enemies and weather factors in Assiut governorate during 2019 and 2020 seasons.The samples were examined from June to September to determine the population of Limothrips cerealium (Haliday, 1836), Rhopalosiphum maidis (Fitch, 1856) and Sesamia cretica Lederer, 1857 and its the associated predators. The population of L. cerealium recorded a peak in the 4th week of July 2019 and the 1st week of August 2020. The highest population of R. maidis occurred in 1st week of September at both seasons. The simple correlation and regression between L. cerealium population and three weather factors were insignificant in both seasons while S. cretica population were found to be significant with R.H%. The population of R. maidis in the 1st season was insignificant negative with temperatures but was significant in the 2nd season. The plant age was more effective than the weather factors on the population of the three insect pests. The common predators were Orius albidipennis (Reuter, 1884) and Scymnus interruptus (Goeze, 1777)which were highly significant with all three insect pests.
4

Toxicological and biochemical effects of some safe compounds on fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

100%
Abd El-Rahman S. F., Haron E. N., Gaber N. M.
Polish Journal of Entomology
|
2025
|
tom 94
The fall armyworm, Spodoptera frugiperda, is known as one of the most important insect pests in Egypt, depending on the wide host range and quick adaptation to climatic factors. The current study aimed to evaluate the toxic and biochemical effects of photosensitizer (magnesium chlorophillin (Mg-Chl), nanocomposites (graphene oxide (GO) nanomaterial over magnesium chlorophillin (Mg-Chl/GO), and essential oil of lemongrass (Cymbopogon citratus) against the second instar larvae of S. frugiperda. Four concentrations of three compounds were tested. Thereafter, some biochemical aspects of the surviving second instar larvae of S. frugiperda after each treatment were recorded. The findings indicated that the larval mortality rate exhibited a positive correlation with increasing both the concentration of tested compounds and exposure duration. The mortality percentage of the Mg-Chl/GO composite was higher than magnesium chlorophillin (Mg-Chl) and essential oil of lemongrass. According to LC50 values, Mg-Chl/GO (LC50=0.0005 ml/ l) as more effective than Mg-Chl (LC50=0.227 ml/ l) and C. citratus essential oil (LC50=7.5 ml/ l). Also, according to LT50 values, the Mg-Chl/GO nanocomposite had higher time-response effectiveness on S. frugiperda larval mortality % than the photosensitizing Mg-Chl treatments. At the exposure of 1 hour of light, LT50 there was 2.306 and 2.578 days at Mg-Chl/GO (10-2) and Mg-Chl (10-2), respectively. The three tested compounds demonstrated a markedly significant reduction in total protein levels when compared to the control group. Detoxification enzyme activity in treated larvae indicated a significant effect on acetylcholinesterase (AchE), GST, and CaE compared control.
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