The abundance of certain cotton insect pests and associated predators was
studied on Giza 89 cotton variety under field conditions of Middle Delta during 2002
and 2003 seasons. Weekly count of total number of insects/1 00 seedling (or leaves
or plants or bolls)chosen at random indicated that:
During early- to mid-season of 2002 and 2003, Aphis gossypii (Glover)
showed one peak of abundance in first of May, while Emp < /em>oasca spp. had one peak
in late of May, 2002 and first of June 2003. Thrips tabaci (Lind.) had two peaks
through May and June and it was the most abundant pest followed by A. gossypii,
Empoasca spp. and Bemisia tabaci (Genn.). Coccine/la undecimpunctata (L.)
reached its highest abundance in may, while the rest predators peaked through June
synchronizing with the higher numbers of aphids and thrips. The most abundant
predator was C. undecimpunctata; while, Chrysoperfa camea (Steph.) was the least
abundant one, A. gossypii positively correlated with B. tabaci and T. tabaci, while
Empoasca spp. negatively correlated with A. gossyp < /em>ii and B. tabaci. Relative humidity
affected A. gossyp < /em>ii and B. tabaci positively in 2002 and negatively in 2003, but the
reverse correlation was observed with Empoasca spp., and T. tabaci. Temperature
positively affected Empoasca spp., in the two early to mid- seasons, and T. tabaci in
2002 one only, but it negatively affected A. gossyp < /em>ii and B. tabaci in both seasons. A.
gossyp < /em>ii and B. tabaci were more influenced by total predators than Empoasca spp.
and T. tabaci.
During mid- to late-season of 2002 and 2003, A. gossyp < /em>ii showed one peak
of abundance in late July and another peak in late August, while B. tabaci peaked
twice through August and September. Also, Emp < /em>oasca spp. reached their highest
abundance through August, while the maximum abundance of Pectinophora
gossyp < /em>ie/la (Saund.) and Earias insulana (Boisd.) population were occurred in the
end of both seasons. All insect pests except P. gossyp < /em>ie/la were more abundant in
2002 season than the same insects in 2003. B. tabaci was the most abundant pest
during 2002 season and A. gossypii during 2003 one, while E. insulana was the least
abundant pest during the two seasons.
C. undecimpunctata peaked through August of 2002 and 2003 seasons;
while, the rest predators mostly peaked through July and August of the two seasons.
Paederus alfierii (Koch) was the most abundant predator, while Orius sp. and C.
camea were the least one through 2003. The correlation between all insect pests
themselves were positive except Emp < /em>oasca spp., which correlated negatively with P.
gossypie/la and B. insulana in the two seasons. Relative humidity affected A. gossyp < /em>ii
and P. gossypie/la positively in 2002 season, while B. tabaci and Empoasca spp.
influenced by it positively in 2002 and 2003. On the other hand, E. insulana
negatively correlated with it in the two seasons. Temperature affected A. gossyp < /em>ii and
B. tabaci positively on 2003 and negatively in 2002, while the correlation was
positively with Empoasca spp. and negatively with P. gossyp < /em>ie/la and E. insulana in
the two seasons. Total predators were more effective on A. gossyp < /em>ii, B. tabaci and P.
gossyp < /em>ie/la during 2003 season than 2002 one. While, these predators were more
effective on Empoasca spp. and E. insulana during 2002 season than 2003 one.
These findings have a great importance in cotton integrated pest management.