الفهرس 
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Abstract
VIII. SUMMARY
Many pests attack the cotton (Gossypium barbadense L.) crop, but the spiny bollworm, Earias insulana (Boisduval), (Lepidoptera: Noctuidae), is the most devastating enemy. It not only causes significant crop loss but also has an impact on the quality of the lint. Chemical control is extremely difficult, because the insect spends most of its time inside the fruiting bodies and is not directly exposed to chemical spray.
The goal of the current study was to build a forecasting system for establishing an IPM program for the control of the tested insect pest. This occurs by studying some biological features of the pest as a principal and primary step to determine its necessary heat unit’s requirements.
Remote sensing technologies were used in the current study in order to predict the number and time of seasonal generations of this insect pest under field conditions. Remote sensing technologies also were used as advanced technique for detecting if the pest is present in its host or not without exposing the host to loss.
The obtained results are summarized as follows:
1. Laboratory Studies:
The insect was reared on an artificial diet under three constant temperatures (20, 25, 30ºC), to estimate the effect of different constant temperatures on the duration length and the rate of development of each developmental stage of the spiny bollworm and its generation. In addition, for detecting lower threshold of development (t0) and accumulation heat units.
1.1. Egg stage:
- The average of incubation period decreased gradually as the temperature increased from 20 to 30ºC, being ≈ 5.36, 4.02 and 2.67days at 20, 25 and 30 ºC, respectively.
- The threshold of egg development (t0) was 10.64 oC.
- The average of thermal units needed for the completion of the development of this stage were ≈ 53.19 dd’s.
1.2. Larval stage:
- Means of E. insulana larval duration were ≈ 22.78, 15.55 and 12.74 days at 20, 25 and 30 ºC, respectively.
- The lower threshold of larval development (t0) was 6.97 ºC.
- The average of thermal units needed for completing the larval development period was 290.19 dd’s.
1.3. Pupal stage:
- The average of duration length of pupal stage of E. insulana at temperatures range from 20 to 30ºC, were ≈ 16.44, 10.83 and 7.28 days, respectively.
- The lower threshold of development (t0) was 12.34 ºC.
- The average number of thermal units needed for this stage to develop within the tested temperatures range was 130.53dd’s.
1.4. Pre-oviposition period:
- The pre-oviposition duration was negatively correlated with temperature at the 20–30 oC range, and it was 3.81, 2.11, and 1.90 days at 20, 25 and 30 oC, respectively.
- The lower threshold of development (t0) was 9.05 ºC.
- The mean of thermal units needed for the E. insulana ovaries development to start depositing eggs was 38.38 dd’s.
1.5. The complete generation:
- The mean durations of E. insulana generation was ≈48.39, 32.51 and 24.59 days at 20, 25 and 30ºC, respectively.
- The lower threshold of development (t0) was 9.68ºC.
- The average of thermal units needed to complete the E. insulana generation was 499.03dd’s.
2. Determination of observed seasonal generations of spiny bollworm male moths by using sex pheromone traps in cotton plants in Field Trials:
This section of the current investigation was dedicated to study the fluctuation in the population density and detect the number of observed seasonal generations of E. insulana, throughout three successive cotton seasons (2020, 2021 and 2022) during the period from the 1st week of May to the 1st week of October. Five sex pheromone baited traps were used for achieving this purpose at the rate of one trap / Feddan at Qaha Farm, which located in Qaha, Qaluobiya Governorate, Egypt.
Results indicated high population fluctuations during different months of the three cotton seasons. There were four observed generations in addition to the overwintering generation for the SBW in the field during each season.
3. Prediction possibility of E. insulana generations in relation to heat unit’s accumulations:
Satellite remote sensing technology and using the heat unit summation method was used to expect the emergence, population density of E. insulana and their population peaks to help reduce monitoring time and timing of control measures in cotton fields.
The data showed that this insect pest had 4 expected generations on cotton plants during the period extended from the 1st of May to the 31st of September at Qaluobiya Governorates under studies, in addition to the overwintering generation from which males reached their peak during the second half of May at Governorate under study.
The expected peaks of generations could be detected when the accumulation thermal units reached 499.03 dd’s.
For the first season (2020), there were 4 generations in addition to the overwintering generation for the SBW in the field (observed and expected), the observed peaks for the overwintering, the first, the second, the third and the fourth generation were at 25th May, 21th June, 18th July, 14th August and 10th September, respectively, when the average number of male moths per trap each day was 16, 26, 44, 46 and 23 male moths, respectively. On the other hand, the expected peaks for the same generations were at 25th May, 24th June, 19th July, 12th August and 5th September for the overwintering, the first, the second, the third and the fourth generation, respectively, at 503.4, 505.4, 497.3, 506.2 and 498.1 dd’s, respectively, with average deviation intervals -3 days earlier than the actual peaks.
For the second season (2021), there were 4 generations in addition the overwintering generation for the SBW in the field (observed and expected), for the overwintering, the first, the second, the third and the fourth generation, the observed peaks were at 31th May, 27th June, 21th July, 17th August and 10th September, respectively, when the average number of male moths per trap each day 33, 54, 33, 61 and 31 male moths, respectively. While the expected peaks for the same generations were in 31th May, 28th June, 21th July, 13th August and 6th September, respectively, at 492.7, 509.4, 493.0, 504.5 and 495.1 dd’s, respectively. With deviation intervals -7 days earlier than the actual peaks.
For the third season (2022), there were 4 generations in addition the overwintering generation for the SBW in the field (observed and expected), for the overwintering, the first, the second, the third and the fourth generation, the observed peaks were at 28th May, 24th June, 18th July, 11th August and 7th September, respectively, when the average number of male moths per trap each day 23, 55, 59, 44 and 31 male moths, respectively. Alternatively, the expected peaks for the same season were in 28th May, 23th June, 18th July, 11th August and 4th September, respectively, at 503.7, 503.8, 495.3, 498.7 and 495.7 dd’s, respectively with deviation intervals -4 days earlier than the actual peak.
In general, there were a positive period between the prediction and the actual observations, and the period is also as short as possible for a successful forecast to occur and get a good accuracy of prediction which occurring according to the population patterns dd’s of SBW. The earlier knowing of the insect abundance has a great importance in early preparation of pest control materials and could be helpful when IPM control tactics are considered.
4. Using another applications of remote sensing for detection the spiny bollworm:
4.1. Spectral measurements:
By using a specroradiometer, it found that, the reflectance of healthy cotton bolls was higher than that of all other infected cotton bolls. Along the whole spectrum, the reflectance of moderately infected bolls is higher than the reflectance of severely infected bolls. ANOVA and Tukey’s HSD test was done to determine which spectral zone is more efficient in distinguishing between healthy and infected cotton bolls. Results revealed that the blue spectral zone was found to be the best for spectrally identifying infection in cotton bolls, i.e., distinguishing between healthy and infested bolls.
4.2. Vegetation Indices calculation:
Calculation of spectral vegetation indices (MCARI, TCARI, NPCI, NDVI, NDWI, WBI) from reflectance values carried out, in order to detect the best indices affected by pest infection. The results showed that there was a significant difference between “NPCI” values of health and different degree of infestation samples. The study found that in the visible region of the spectrum, infected cotton bolls reflected more energy than healthy ones.
4.3. Thermal imaging:
By imaging the cotton bolls abnormal warmth and wetness were observed; our results showed that the maximum temperature difference (MTD) between healthy bolls and bolls with different degrees of infection was found in the range of 20.9 °C to 21.9 °C. The temperature of diseased bolls was 1 °C higher than that of healthy bolls on average. These findings were also illustrated by histogram adjustments to highlight the temperature variables inside the boll.