الفهرس 
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Abstract
The purple lined borer, Chilo agamemnon Bles. is considered as one of the major pest problems in sugarcane cultivation areas in Middle and Upper Egypt. This pest causes serious damage to sugarcane plantations resulting in great losses in cane and sugar yields. During the last few years, Trichogramma evanescens is mass reared and released in large numbers on sugarcane fields in Middle and Upper Egypt for controlling this insect. The present study, however, aimed to add new knowledge and informations concerning increase benefits of this important parasitoid for control of this serious pest. This, of course will avoid the use of pesticides entirely and keep the crop and the environment clean from pollution. The present study includes laboratory experiments concerning the parasitoid and its hosts that could be bred on successfully and economically. The best conditions of storage of the egg host parasitized or not parasitized in order to use it for releasing in the proper time were also studied and investigated. However, in the field experiments, a new technique for releasing the parasitoids was applied in order to increase the parasitoid efficiency. However, the scope of the present study included the following points:
A- laboratory Studies:
1. laboratory rearing of hosts of the parasitoid T. evanescens.
In order to obtain eggs of hosts that are well known to be parasitized by Trichogramma three hosts were used. These are, the angoumous grain moth Sitotroga cerealella (Olivier), the mediterranean flour moth, Ephestia kuehniella Zell. and the rice bran moth, Corcyra cephalonica Staint. This was carried out in order to evaluate :
1- The host preference of the parasitoid :
Two trials were designed to determine the acceptance and preference of the three forementioned lepidopterous hosts to be parasitized by T. evanescens females which had been collected and reared from parasitized egg-masses of the purple lined borer C. agamemnon.
In the first trial, eggs of S. cerealella, E. kuehniella and C. cephalonica were exposed, separately, to T. evanescens female to determine fecundity of Trichogramma female, total developmental period, rate of parasitoid’s emergence, sex ratio and longevity. In the second trial, eggs of the same three insects were exposed, collectively to parasitoid females and the same parameters were estimated for each host.
The results of the two trials showed that the eggs of the three hosts are acceptable for parasitization by the adult parasitoid with insignificant difference in the rate of preference among the tested egg hosts. However, eggs of the C. cephalonica and E. kuehniella were more preferable than that of the S. cerealella concerning the average number of parasitized eggs/ female, rate of emergence, sex ratio, total developmental period and longevities for both male and female.
Although, the eggs of the S. cerealella as a laboratory breading host was the less in the concerned tested parameters in comparison to the other two hosts, but the easy, simple and cheap use of it, encourage using of this host for laboratory breading and releasing in the fields
2-Effect of different temperatures and relative humidities on some biological parameters of T. evanescens reared on S. cerealella eggs:
To determine the optimum hygrothermal condition for mass rearing of T. evanescens five degrees of temperatures (18, 22, 26, 30 and 32 ºC), each combined with three degrees of relative humidity (45, 75 and 90 ± 5% R.H), were tested to estimate : total number of parasitized eggs per female, adult emergence rate, longevity of both sexes, sex ratio and the total developmental period of the parasitoid.
The results indicated that the optimum combination for mass-rearing of T. evanescens was 26 ± 2ºC combined with 75 ±5% relative humidity, since this combination resulted in the highest values of the number of parasitized eggs per female, adult emergence rate, sex ratio and longevity of females and males.
3- Effect of different food sources on some biological parameters of the parasitoid adults T. evanescens::
The experiment was conducted to obtain more progeny during the laboratory mass- rearing of T. evanescens. The lowest average of total progeny/female of T. evanescens was produced by the starved females. On the other hand, the highest total number of progeny was produced when females were fed on 20% sugar solution or 20% honey solution plus dry yeast.
The productivity per female was averaged 31.8, 54.2, 74.6, 103.8, 104.7 and 105.3 eggs, when the females were starved, fed on water, 10% sugar solution, 20% sugar solution, 20% sugar solution + dry yeast and 20% honey solution + dry yeast, respectively. Where as the longevity of females were averaged 2.1, 2.7, 3.4, 9.8, 10.3 and 10.3 days respectively. Meanwhile the respective longevity of males were averaged 1.6, 1.9, 2.0, 4.9, 5.2 and 5.5 days, respectively. However, the use of different nutrient sources has led to a difference in the sex ratio but it was always in the favour of the females ratio what ever the source of food. Therefore it is recommended to feed the adults of the parasitoid on 20% sugar solution or 20% honey solution plus dry yeast.
4- Storage of S. cerealella eggs as a laboratory host :-
This part of study aimed to determine the procedure which could enable us to store the host’s eggs to a maximum period for using when it is needed. This study was divided into two sets of experiments.
In the first set, newly deposited Sitotroga eggs were kept in freezer (-5°C) for 1 or 4 hours after that eggs were kept at the optimum hygrothermal conditions of 26 ± 2°C and 75 ± 5% R.H. to be exposed daily to T. evanescens. The results showed that the maximum period for storing Sitotroga eggs was 15 days after which the eggs were not parasitized by the parasitoid female, the differences between the two freezing periods were insignificant
In the second set of experiments, Sitotroga eggs were put in the freezer (-5°C) for one hour only then were transferred to the refrigerator (5°C). The eggs were exposed weekly to T. evanescens for 7 successive weeks. The maximum period of storing Sitotroga eggs in the refrigerator (5°C) was found to be 6 weeks. On the 7th week, the eggs become unsuitable for parasitization.
5- Storage of the S. cerealella parasitized eggs by the Trichogramma parasitoid.
This part of study aimed to demonstrate the most suitable stage of the developing parasitoid to be stored and the maximum period of storage at this stage. The results indicated that the egg stage of the parasitoid was the most suitable stage for storing since it showed the maximum rates of adult emergence compared to the other stages of the parasitoid (larvae or pupae) during all the storage periods (6 weeks).
B. Field experiments.
Improvement of releasing technique of T. evanescens against C. agamemnon in sugarcane fields.
The common method which has been used for long time concerning the release of T. evanescens in the sugar cane fields by using the conventional device, may allow certain types of predators to attack the parasitized eggs of S. cerealella that glued onto the pieces of carton inside the device. This, however could make a mistake in evaluating the efficiency and activity of the parasitoid. Therefore, a new technique for improvement of releasing efficiency of the parasitoid was adopted in comparison to the conventional device and the check. This was carried out in sugar cane field during 2004 and 2005 seasons.
The field results indicated that the new releasing device was significantly superior in comparison to the conventional releasing method and the check. By using the two releasing methods in the first year during May till November, the average monthly numbers of egg-masses of C. agamemnon that collected were 10.3 and 12.2 and 13.9, while they were 9.7, 11.3 and 14.1 in the second year of the experiments for the new releasing device, the conventional device and the check, respectively. Meanwhile, the average rates of the parasitized egg-masses when using the forementioned two devices and the check during the same period of the study, were, 72.9, 56.5 and 37.7 for the season of 2004/ 2005 and 41.3 for the season of 2005 / 2006, respectively. Furthermore, results also showed that the rate of parasitized eggs / egg-masses was significantly higher in the new releasing device in comparison with the conventional release device and of course the check.
However, at harvest time and in order to clear out the effect of using the new releasing method in comparison with the conventional release device and the check, the rates of infested stalks, infested joints, circular tunnels and number of holes / plant were evaluated. Results showed that the whole forementioned parameters used were in favour of new releasing device followed by the conventional device in comparison with the check. Therefore, it is recommended to use the new releasing device of T. evanescens in order to decrease the infestation rate of the purple lined borer C. agamemnon in the sugarcane fields of Middle and Upper Egypt.