الفهرس 
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Abstract
Biological and Behavioural studies on certain Scarabaeids of Agricultural
Importance in Egypt The present work has came as a continuity of a previous study on the peach cockchafer Pachnodafasctata (Kamel 1988). The present study is concerned with some behavioural studies on two searabaeids of economic importance in Egypt, t-e the hairy rose beetle Troptnota squalida Scop. and Pachnodafasctata F.. Results of laboratory and field studies demonstrated that there are some similarities between the behaviour of the two species. Each of the two species bas one generation a year (univoltine insect). The adults of both of them are diurnal, becoming active during the day, especially in sunny weather and mating takes place on branches of the favourable fruits and ornamental trees. Yet, no copula was
observed during the flight. Females of T. squalida and P. fasctata lay their
eggs in the soil, where the hatched larvae construct their tunnels. Females of T. squalida showed different degrees of preference to different soil mixtures as oviposition media; it was found that a soil mixture composed of clay, cattle dung, peatmoss and sand in equal proportion, was the most attractive one where more eggs were laid by the female. In addition, females of T. squaZ ida produced larger number of eggs when fed on banana, followed by green bean flowers, mollasses, cauliflowr, concentrated and diluted honey, descendingiy.The 3” instar larvae of T. squaZida make tunneles at depths ranging between 6 and 34 cm from the soil surface. At the end of the 1arval stage, the fuIlqrown larvae construct earthen cocoons by semicircular repeated movements of the caudal end of the abdomen, soil particles are plastered with gut contents discharged through regurgitation. Within this earthen cell the larva turns into pupa. T. squaZida larvae were reared in different soil mixtures to examine the best soil composition as rearing media. It was found that a soil composed of clay, cattle dung, peatmoss and sand is the best one. In this medium larvae underwent the last 1arval period (19.6 + 2.48 days) in comparison with the: other tested mixtures. Both P. fasciata and T. squaZida larvae were reared in soil
containing different germinating seeds, i-e barley, clover, white maize and beans
in case of P. faseiata and barley, clover, white maize, grass and beans in case of T.
squalida. It was found that larval weight was more increased when reared in soil
containing barley than in other treatments in both species. In addition, the two species were exposed to different coloured lighu (white, blue, green, yellow and red). It was found that the beetles were attracted to white light, followed by blue, green, yellow and red, respectively. By feeding the adults of the two species on four naturally occurring sugars i-e (glucose, fructose, sucrose and maltose). Sucrose was found to attract higher number of adults, and a concentration of 0.5 m sucrose seemed to be the most attractive to the two scarabaeids under investigations. However, all the:tested sugars were not strong feeding attractants’ to the beetles of the two species under
investigations. Two scarabaeids were reared under different constant temperature i-e the 9”C, 2D”C, 3D”C as well as at room temperature. It was found that in case of T.
squal ida no hatchability was recorded for eggs kept at 9”C indicating this degree
was too low for the embryonic development; also the same thermal degree was very
damaging to the 1«and 2””instar-larvae of. T. squalida and the 3’” instar-Iarvae
of P. fasciata. Thus, keeping T. squalida eggs or larvae or the 3’” instar-Iarve of P. jasciata at such low temperature for regulating the laboratory culture is not
feasible. However, at 2D”C egg hatchability was moderate and the same could be
said for the 1«and 2””larval instar of T. squalida. In case of the 3n’IarvaI instar
of P. fasctata the duration period extended at 2D”C (247.04 ;t. 16.5 days)
compared to that of room temperature (192.2 + 5.1 days). On the other hand, at
3D”C T. squalida eggs started to hatch on the 3’” day while the remaining eggs
hatched on the T” day i-e the incubation period was shorter at higher temperature
(30”C) than at low temperature. In addition, the duration periods of the 1”,2”” larval
instar of T. squalida, 3’” larval instar and pupae of P. Iasctata were shorter at
30”C than at other tested temperature. At this degree the eggs were healthy and the
larvae well developed, active, fed normally and their weight increased and moulted
quickly.In respect to the dult behaviour the number of males and females of
T. squal ida entering the soil and the time they spent inside it under semifield
conditions were examined. It was found that the beetles resort to the soil to escape
hot weather, when the temperature was 17.3°C + 2.02°C ranged between 10 and
25°C and the air temperature increased (25°C) the mean number of females entered
the soil from 9 AM-16 PM. 2.96 + 1.5 and the mean time they spent was 120.7 ±
29.1 min. While the mean number of hidden males at the same time was 1.4 + 0.5
insects and the mean time they spent was 34.1 + 15.8 min. In genera.l the number
of females was larger than males because the females lay their eggs in soil so they
tend to spend longer time.The susceptibilty of 3’” larval instar of P. Iasctata and the: adults ofT. squalida were tested in the laboratory to there chemical insecticides
(Methomyle, Hostathion and Furadon), Values of LC,. and Lc., were calculated in each case throughout 4 days following the insecticidal applications.