الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 189 |  |  |
| | | from | 189 | | |
Abstract
I. BIOLOGICAL SfUD.t1!:S ON ~~_CAUjE~ WAlDa I
1) The shortest and longest mean incubation periods
recorded were 4 and 6 days for the generations starting at
the beginning of August and October 10 respectively. 4-
negative eo?relation existed between the incubation period
and both temperature and relative hUmidity.
2) The species passed through 6-8 instal’s, the durations
of the last two were the longest. The shortest larval
perie d was 47.7 days during August, but Lezvae of the fourth
generation starting mid October overwintered and lasted 122.3
days. ~here was a highly significant negative correlation
between the duration of the larval stage and temperature ,
but the corre 1ati on between i t and the ra1e tiva humidi ty wes
Bignificantly pam ti ve .•
3) The pupal duration ranged between 6.2 and 17.7 days.
’rhe pupal stage was DII.lchaffected by temperature J but the
effect of the relative humidity was 1888 pronounced.
4) Under normal laboratory condi.tions in Kherga tom t
Q. cauteUa had 4 generatione B year. Thewinter generation
was the longest ( 145.3 days ). The generation starting at
the bee;Lnning of August was the shortest ( 62.2 days).
5) ~e mean number 0t eggS lei d by a single femste
dunng 1ts whole life ranged between 90 and 104 with a maximum
of’ 239 and a mean of 26-41 eggs per female per day.
6) The longevi ty of both sexes of moths seemed to be
alm.ost equal with a tendency for females to live slightly
longer ( 2-12 days for maleBand .3-11 for female 8 ). A sex
ratio of about 1 : 1 was obtained.
II. E COLOGICAA STUDI]f§
1) The folloWing insects were re corded as pesta of
dates in Kha1”gal”egion : st-tra.cheya smydr!ula, Are.n1pses
sabella, Virachola l.j.vi’!, Cadl”a spp , and 9a£jJophji.lua spe caea ,
the tONer proved to l:Je the most serious.
2) Infestation wi th B. smydraula and!. sabella appeared
in date bunches early in the season ( March 25th ), rea ched
ita highest peak in Eatrache~ (40%) in May and JWle, but no
defini t. peaks were observed wi th Arenj.psea. At the beginning
of September, infestation with both species almost d1aappe8~d.
Fallen dates showed the first sign of damsge in April and was
sUbject to considerable fluctuations.
J) Infestation wi th the late season pests •.-V. livia, Osdra and Qarpoph11Bl spp. appeared su.cceam w1y. The fi:.--st
records of their ocaurrence in date bunches lWU’8 on ¥By 6,
uy ,0 and JUly lat., l’8Spect1veJ.,-. Infestat100 iDCN8sed
gradually and the Peaks ( 31.3%. 27.0% and .2.3.9%~or these
pests respectively) were reached in August. Towards the
end ot this month and beginning of September, infestation
by V1rachols reached a vezry low level, while i t 8-’~ta1neda
relati vely h1gh level in Gadra and Clrpop!alua.
4) No signs of damage by 1- 11via were observed in
date bunches betore ~ay; but careful examination of green
veget~ tion in the area revealed the presenoe of an a1tel’-
native host plant; the green pods of ~c;ac1.!which weft
severely infested at the same time~ and harboUl”ed a lngh
populetiOll of larvae. In fallen dates, infeat& ti.on appeared
one week after their appearance in bunches and was in most
cases higher than in date bunches.
lnfestation wi th Cadr8 in fallen dates showed e trend
similar to that of bunches, but the percentaB,’e of infestation
in the fOJ.’lller Nmained always lower than in tile latter.
Larvae of Qarpophi.lu8 were never observed in date
bunchea before the begLnning of July, their occw.-rence followed
that of V1rAchola. At the end of the fI-Uitine season,
. .
. nearly all fallen dates oontained lw.-vae.
5) LUring the period J.pril-september~ .3 d:1stinct peaks
of Batrschedra and 2 smaller ones for ~ -re recorded.
Samples of fallan d’-a betweell October and I~oh _waled the
pzeesence of Ii vina 18~vee of both species_
The popu.}.ation o£ V,;Lraehole larvae showed 6-7 peaks,
one being of diminisbJ..ng si.0S occurred on date frui ts (Ju.ly
19 ), the remeining occurred in AQS~ pods.
Four peaks of larvae of ~dra app, were observed; two
on date bunches and another two larger peaks on fallen d[i~s.
6) As a general rule, the semi-dry date ”variety Saidit1
was more liable to be infested wi th the three main peste:
1?. BDlYdraula, 1. Uvia and Qadre ap. than either soft or
dry date varieties. Infestation with Batr89hedra wes in all
deta varieties higher then that of the other two peats. The
percentage of infestation was proportional to the heisht of
palm, the taller the tree, the less susceptible it was to
infests tion.
7) Moths of A. sagell~ WSM attracted to the light
trap from March to October shcwins: two periods of abundance
and 4 peaks. The first three peaks occurring in May, June
and July were much hj,gb.er than that of Auguet. The pest had
4 generations a year lsati.n& 8-10. 7. 6 and 8 .-les respectively.
Dey mexilDUDl temperatUres ranging between J3 and 36°0
( existing during the first brood ) were favourable for moth
acti vi ty. Hieber rmges ( between 37 and .36°0 ) prevailing
in the seoond brood, proved unfavourable. In 1971. the most
sui table night temperature for moth 8c’tiy1:ty lie between 19 ~..”. ~~
and 22°0. Whenraised to 24°0, an insignificant negative
correlation was observed between temperature and moth activity.
The simple correlation values between the daily ni,sht
relati ve humidi ty and activity of moths W82’e significan tly
negAtive except for the second brood of 1972 which was stati
Bti cally 1nsi gni fi cant •
•.
1) satiBfactQ~ protection of date bunches from infests
tivn wi th!. 11via and cadr8 was achieved by covering the
bunches durin g the first half of July e1ther by jute
bags or haIfa weeds. the letter being more aconomic.
2) Almost complete control of date pests was achieved
by oollection and destJ.1’Uctionof fallen dates, old bunches ,
spathes. leaves. fibrest shoots, shrubs, Acacia pods ( as soon
as they appear), weeds and all otner re sidues that are likely
to contain fallen dates or harbour larvae or pupae of these
pests. In the following year, pests were very tew and damag;e
to the crop negl1g1 ble ( ranging between 0.1 and 5.5% ). The
cleaning procedure reflected upon the yield. !he average
yield of frui ts per u-ee was above 85 ki.lograms in cleaned
areas compared to 7 _8. only wbsre no cleaning wes dane.
With the .recogni tion of the effectiveness of this
method of control whenapplied on a large seale, cleaning and
cutting doV\!lof AC8c18 trees became an established procedure.
The practice was extended until now the entire area is usually
cleaned annually under the supervision of the Ministry of
Agriculture starting from October till the end ot Januenoy.