الفهرس 
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Abstract
SUMMARY
In Egypt, as in other countries, plant production for human and livestock consumption is threatened by a wide range of insects and arthropod species. Among the serious pests that cause big loss of field crops as broad bean and maize are the cowpea aphid, Aphis craccivora and the corn leaf aphid, Rhopalosiphum maidis.
Biological control involves the use of natural enemies to control pests. Generally, spiders are considered to be one of the most important predators which can be used as biological control agents of several important agricultural insect pests.
This study included the following points:
1. Seasonal dynamics of Aphis craccivora and Rhopalosiphum maidis:
The cowpea aphid, Aphis craccivora and the corn leaf aphid, Rhopalosiphum maidis are common pests of broad bean and maize crop which are considered as economically important crops, mainly for their use as a food for human in Egypt.
a. This study was conducted at Qaha research station, Qalubyia governorate during two successive years, 2017and 2018 on broad bean and maize crops. Infestation on broad bean and maize started with low incidence in winter (January) and early summer (May& June), respectively. The monthly levels of A. craccivora infestation was gradually increased to reach two peaks in February and in March and represented 33.6 & 37.2% of the total collected life stages in the broad bean season 2017 and one peak 38.5% in March 2018. Also, the monthly level of R. maidis infestation was gradually increased to reach maximum in August and represented 42.7% & 41.8% of the total collected life stages in the maize season 2017 and 2018, respectively.
b. In both infested crops, the immature life stages were the most abundant life stage of the total stages collected in each month and the unwinged (apterous) adult females predominated winged (alate) females monthly collected.
c. The obtained results revealed that infestation with winged females started relatively late on each crop sometimes reaching February and July on broad bean and maize, respectively. Also, winged females started disappearing during the last month (April & September, respectively) of the season of each crop.
d. Generally, the total number collected of each of A. craccivora and R. maidis life stages was higher in 2018 season than 2017 season on each of broad bean and maize crop while the infestation with total life stages of A. craccivora and R. maidis was higher on broad bean crop (419&548 aphid stages) than on maize crop (234&385 aphid stages) during the two successive years.
2. Spiders associated with Aphis craccivora and Rhopalosiphum maidis on broad bean and maize crops:
a. One thousand four hundred and eighty six spiders belong to 10 families of order Araneae were associated with aphids and collected on broad bean and maize crops at Qaha research station in Qalubyia Governorate, Egypt during two successive years, 2017 and 2018. Of the collected 10 families on both broad bean and maize crops Philodromidae was the most abundant in both years of study constituting 25.63% of the total collected spiders (1486) followed by Salticidae (19.04%), Theridiidae (18.37%), Thomosidae (17.83%) then Lycosidae (7.20%) followed by Cheiracnthidae and Araneidae (3.70%), Linyphidae (2.35%) then Dictynidae (1.34%) and Aglenidae (0.80%).
b. On broad bean, seven hundred and seventy eight spiders represent 10 families were associated with A. craccivora in both 2017 and 2018 seasons. The collected families included the aforementioned 10 families. Philodromidae was the most abundant family on broad bean crop in both years of study constituting 26.34% of the total collected spiders (778). Most of the spider families started appearance with small numbers in winter (January) then gradually increased to reach peaks in spring (March).
c. On maize, seven hundred and eight spiders represent 8 Araneae families were associated with Rhopalosiphum maidis and were collected on maize crop. Philodromidae was the most abundant family on maize crop in both years of study. Most of the spider families started appearance in late spring (May) and other appeared in summer (June) then gradually increased to reach peaks in summer August then decreased in September.
Generally, the total number of spiders collected in both years of study and in each of 2017 and 2018 were higher on broad bean (778, 357&421, respectively) than on maize (708,346&362, respectively) and in 2018 than 2017 on each of broad bean and maize.
3. Effect of temperature and prey quality on duration, food consumption and predation rate of spiderlings of Thanatus albini and prey quality on Thomisus spinifer fed on immatures and adult females of A. craccivora and R. maidis:
The effect of temperature and prey quality of a monotypic diet of immatures and adult females of the cowpea aphid Aphis craccivora and the corn leaf aphid, Rhopalosiphum maidis on food consumption, predation rate and development duration of spiderling of Thanatus albini were investigated at 3 temperatures (15, 27, and 35˚C). Effects of the prey quality of the monotypic diet of each aphid on the tested parameters were studied in spiderlings of Thomisus spinifer and on reproduction in adult females of both spider species at 27˚C.
a. The effect of the three tested temperatures varied on spiderlings of Th. albini and was optimum for prey consumption and predation rate at 27˚C. At 15˚C, no spiderlings were hatched and whole life cycle was arrested. At 35˚C, stage duration of spiderlings were shortened and development was enhanced but prey consumption and predation rate (except on adult aphid) were reduced to significantly lower numbers at 35˚C than 27˚C. At each of these temperatures in Th. albini and at 27˚C in T. spinifer, durations of spiderling stages were gradually increased by increasing the age of the spiderling and reached the longest duration in the last stage (7th spiderling).
b. Generally, durations were longer for spiderlings when fed on immatures than on adult females of each aphid species and on A. craccivora than R. maidis in Th. albini and on R. maidis in T. spinifer, which did not feed on A. craccivora.
c. The early three spiderlings could not feed on adult female aphids but only on immatures. However, each of the 4th to 7thspiderling stage consumed more immatures than adult female of each aphid species, A. craccivora more than R. maidis and at 27˚C more than 35˚C in Th. albini and only of R. maidis in T. spinifer which refused to feed on A. craccivora at 27˚C. Although durations of spiderlings of T. spinifer were longer than their correspondings in Th. albini, food consumption and predation rates mostly showed no significant difference between the two spider species.
4. Effect of prey quality on reproduction of female Thanatus albini and Thomisus spinifer reared on immatures of Aphis craccivora and Rhopalosiphum maidis.
The rearing of adult females of Th. albini on immatures of A. craccivora and R. maidis had no significant effect (p˃0.05) on longevity (sum of pre-oviposition, oviposition and post-oviposition periods) and fecundity (mean number of eggs/ female). However, a comparison of the two spider species showed that T. spinifer longevity (76.5±1.15 days) and fecundity (175.7 egg/female) were significantly higher than (p˂0.05) those (57.9±1.15 days& 64.25 egg/female) of Th. albini reared on R. maidis at 27 ˚C.
5. Quantitative analysis of basic nutritional components of Aphis craccivora and Rhopalosiphum maidis:
Quantitative analysis of total protein, carbohydrates and lipids in immatures and adult females of the two aphid species was carried out to evaluate their nutritional value to the spiders.
The analysis showed higher concentrations of proteins and carbohydrates in adult females than immatures in each aphid species but both A. craccivora and R. maidis showed similar concentration of each of the basic nutritional components.