الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
The most significant commercial pest in Egypt is the Egyptian cotton leafworm, Spodoptera littoralis (Boisd.). This insect pest considered as a significant cotton-damaging polyphagous lepidopterous insect pest that seriously reduces yield quality and quantity. The larvae feed on about 80 host plant related to different groups, many of them are very important economically.
Both the need for improved output and the increasing stress brought on by plant pests have an impact on modern agriculture. Currently, information regarding pest populations that are present or projected to emerge is provided via variable rate applications using geographic information systems (GIS) and global positioning systems (GPS).
The daily maximum and minimum air temperatures were determined from satellite photos using remote sensing technologies. We used the Advanced Research WRF Version 3 (ARW) modelling system to gather the data. WRFV3 output files contain temperatures for the entire day and 24 hours at Kelvin temperatures, which are then converted to Celsius temperatures by simulation using the formula °C = °K - 273 to determine the maximum and minimum temperatures, which are then converted to degree-days to forecast the frequency and timing of this insect pest’s yearly generations under field circumstances.
The present study aimed to introduce a detailed study in the laboratory and field on S. littoralis. The laboratory studies discuss the biological aspects of determining the needed requirements of heat units for (eggs, larval, pupal, adult stages) to S. littoralis. The field study focused on use sex pheromone traps to monitor the population changes and predict the adult generations in relation to heat unit’s accumulations needed for the growth of S. littoralis throughout three cotton growing seasons (2017, 2018, and 2019). Both of laboratory and field studies are important to for further studies to establish an IPM program for its control.
1- Laboratory studies
a. Developmental stages of S. littoralis
In order to determine distinct temperature constants for each developmental stage, in addition to the pre-oviposition phase and generation, the insect was raised under four constant temperature degrees (17, 22, 27, 32°C ± 1°C).
1. Egg stage
• The mean incubation period dropped steadily from 17 to 32°C, with values of 6.14, 4.56, 2.91, and 1.87 days at these temperatures, respectively.
• The egg development threshold (t0) was 11.8°C.
• The average number of thermal units needed to complete these stages under successful development was 40.1 degree-days (DD’s).
2. Larval stage
• At 17, 22, 27, and 32 °C, respectively, the averages of larval duration was 30.65, 18.70, 15.22, and 11.45 days.
• The lower threshold of development (t0) was 7.56°C.
• The average number of thermal units needed for larva to reach maturity was 283.76 (DD’s).
3. Pupal stage
• Between 17 and 32 °C, there was a negative correlation between the pupal stage and temperature, with the average pupal period varying between 31.64, 15.36, 10.14, and 7.57 days at 17, 22, 27, and 32 °C respectively.
• The lower threshold of development (t0) was 12.27°C.
• The average number of thermal units needed for this stage to mature within the tested temperature range was 149.5 (DD’s).
4. Adult stage
a. Female longevity
1. Pre-oviposition period
• As the temperature rose, it took less time for the ovaries to mature and begin laying eggs. These times were measured as 5.0, 2.6, 1.8, and 1.2 days, respectively, at 17, 22, 27, and 32°C.
• The lower threshold of development (t0) was 12.58 °C.
• The average number of thermal units required for S. littoralis ovaries to mature and begin producing eggs was 23.96 (DD’s).
5. The completion of generation
• At 17, 22, 27, and 32°C, the mean times for S. littoralis generation were 73.43, 41.22, 30.07, and 22.07 days, respectively.
• The lower threshold development (t0) was 10.50°C.
• The generation took an average of 480.6 DD’s of thermal units to complete.
2. Field study
a. Males of S. littoralis moth population fluctuations were monitored by pheromone traps.
The main goal of this point is to use sex pheromone traps at a rate of four traps for experiment area = (seven feddans) in the shape of letter Z in Assuit Governorate, Egypt, to monitor the changes in population changes of S. littoralis over three cotton growing seasons (2017, 2018 and 2019).
The findings showed that over the three seasons under study (2017, 2018 and 2019), there were seven major peaks of male moths, with a few minor peaks that varied in quantity and revealed the flying activity pattern for each season.
b. Prediction possibility of adult S. littoralis generations in relation to heat units accumulations
The ideal time for control was determined by calculating degree days for peak prediction using satellite remote sensing and male moths caught in pheromone traps to identify the dates of observed peaks and matching thermal units to estimate the number of observed and forecast generations. The information revealed that in addition to the overwintering generation, this insect pest had seven annual generations.
The estimated number of thermal units needed to complete the overwintering generation of S. littoralis was used as a starting point to determine when the overwintering generation will really peak between 2018 and 2021.
The overwintering generation:
It is the generation that emerges from the larvae during the winter and spring seasons, which reaches its peak during the second week of May moths reached their real (observed) and (expected) peaks at the same time, during 2017, 2018 and 2019 seasons respectively.
The 1st generation:
The peak of this generation for an expected peak has been occurred during 29, 5, and 31 May throughout 2017, 2018, and 2019 seasons, respectively for (expected and observed) peaks dates according to thermal requirements as the same in 2017 and 2019 years but expected peak was early by one day of the observed peak in 2018.
The 2nd generation:
The peak of this generation for an expected peak has been in 22, 26, and 18 June for 2017, 2018, and 2019 seasons respectively, while the required accumulation thermal units for the expected peak deviated with observed peak early in 2017 by 2 days, in the same time with the observed peak in 2018, but later with the observed peak in 2019 by 1 day.
The 3rd generation:
The peak of this generation for an expected peak has been in 13, 17, and 15 July for 2017, 2018, and 2019 seasons respectively, while the required accumulation thermal units for expected peak deviated with an observed peak early by 1 day to 2017 and 2019 and by 2 days to 2018.
The 4th generation:
The peak of this generation has been to expected peak in 31 July for 2017, but in 10 and 5 August for 2018 & 2019 seasons respectively, while the required accumulation thermal units for expected peak deviated with observed peak later by 2 days to 2017, but early by 1 day to 2018, and in the same time to 2019.
The 5th generation:
The peak of this generation for an expected peak has been in 24, 31, and 26 August for 2017, 2018, and 2019 seasons respectively, while the required accumulation thermal units the for expected peak deviated with the observed peak in the same time to 2017, but later by 1 day to 2018, and early by 1 day to 2019.
The 6th generation:
The peak of this generation for an expected peak has been in 17, 27, and 22 August for 2017, 2018, and 2019 season respectively, while the required accumulation thermal units for expected peak deviated with the observed peak in later by 1 day to 2017, but in the same day to 2018, and early by 1 day to 2019.