الفهرس 
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Abstract
The palm is infested with many insect pests that affect different parts of the palm, whether leaves, fruits, trunk or roots, and the most dangerous of these pests is Rhynchophorus ferrugineus, which feeds internally on palm tissue, so the infestation cannot be detected until its last stages, as the infested palm was severely damaged due to difficulty acting in time to control this insect as no visual symptoms of infection appear. Because of the date palm importance to Egypt, where the production of dates in Egypt reaches 17 million tons annually, and its production represents 17.7% globally, 24.4% of the production of the Arab world (FAO, 2020). The study plan has been drawn up to conduct some field and laboratory studies on the insect to know the times of its spread and the environmental conditions that lead to its reproduction and spread, and then find environmentally safe ways to combat it.
The trials included the following:
5.1. Ecological studies:
5.1.1. Population fluctuation of the R. ferrugineus on date palm farms
The results showed that the adult of R. ferrugineus, existed and fluctuated all over the year with four peaks .
5.1.1.1. Population fluctuation of the R. ferrugineus on date palm farms during, 2016:
The first peak at the first week of Mar with 6.13 adults / trap. The second peak at the second week of May with 4.60 adults / trap. The third peak recorded 2.60 adults / trap at the last week of June. While the fourth peak was 7.07 adults / trap recorded at the first week of October at the first year 2016.
5.1.1.2. Population fluctuation of the R. ferrugineus on date palm farms during, 2017:
The second year 2017 first peak recorded at the first week of Mar with 9.53 adults / trap. The second peak at the second week of April with 8.00 adults/ trap. The third peak recorded 2.87 adults / trap at the last week of May. While the fourth peak was 11.53 adults / trap at the last week of September.
5.2. Laboratory studies :
5.2.1. Some biological studies of the R. ferrugineus
Under laboratory conditions the insect had three generations per year. The results concerning the durations of different stages as well as the insect rate of reproduction throughout these annual generations can be summarized as follows :
5.2.1.1. Duration of egg stage (Incubation period):
The shortest incubation period of egg stage was 2.53±0.18 days was recorded in the second generation .whereas the longest duration of 6.02±0.56 days was obtained with insects of the third generation Temperature had a highly significant negative effect on the incubation period of eggs in the first generation, whereas in the second and the third generation, this effect proved to be statistically non-significant positive in the 2nd generation and negative in the 3rd one. Concerning the effect of relative humidity , it was found that, it was not constant and varied from generation to another .
5.2.1.2. Number and durations larval instars:
The longest larval period of 120.60±2 days was recorded with insects reared in the third generation. Raising temperature and lowering atmospheric relative humidity in the 2nd and 1st generations caused a considerable shortage of larval duration recording means of 98.03±4.32 and 46.06±1.46 days, respectively. As regards the response of larval development to variations of temperature and relative humidity, It is obvious that larval period high significantly influenced, but this effect appeared to be negative for temperature and positive for relative humidity in both 1st and 2nd generation. Contrarily, in the 3rd generation the opposite case was obtained. The obtained results clearly indicated that this insect had from 9 to 12 larval instars. The death of some larvae was observed and it was noticed that the percentage of death differed greatly according to the larval age, but in general it was found that the death percentage in the last larval ages from the 9th to the 12th was higher than that found in the first ages.