USE SPIDERS IN THE CONTROL OF THE PEST SPODOPTERA LITTORALIS (BOISDUVAL) (LEPIDOPTERA: NOCTUIDAE) ON COTTON WHICH WAS SELECTED UNDER GREENHOUSE CONDITION DURING SEASON 2017 AD.

Ahmed R. Aly Taha1, Mohamed H. El-Erksosy1 and Wafai Z. A. Mikhail2. 1. Plant Protection Research Institute, A.R.C., Dokki, Giza, Egypt. 2. Institute of African Research and Studies Cairo University. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History


…………………………………………………………………………………………………….... Introduction:-
The ecosystem were destroyed by chemical production meanwhile the researches must be in the direction of life restoring to it normal, the biological control divided into two parts, the first part is the classic biological control type therefore means inputting predators or parasites to ecosystem. While another type is maintain predators and parasites which already exist in ecosystem. The spiders are one from factors which playing an important role in biological control, Currently it included 46'906 from accepted species (World Spider Catalog Version 18.5 / http://www.wsc.nmbe.ch/), on the other hand the wide distribution qualifies them to be the key factor in the environmental balance to reduce pesticide impacts, also the cotton leaf worm considers from the dangerous pests in Egypt throughout the year, on several host, Younis (1992) so it was necessary use spiders in control this pest to save the ecosystem from the pesticides.

Materials and methods:-
The crop and land of experiment:-The cotton of experiments cultured in Qaha station which follow plant protection research institute, in Qalubia governorate. The land were divided into 3 replicates, (two replicates for two levels of release, and one for land of the control), and plates were made of pipes covered with Guaze fabric, which was sowed in two layers to better withstand weather conditions. A zipper was added to the greenhouse.
The total of the examination were 5 times other than the pre-count, and 20 leaves were examined from each treatment.
Spiders which were released in greenhouse:-300 individuals from spiders were used in the release, they followed 3 families (Salticidae, Theridiidae and Thomisidae) collected from cotton crop fields, thus were defined by external morphological forms. Then saved in incubator in station of research in Qaha, prelude to release them on the pest Spodoptera littoralis.

Calculation of the reduction percentages:-
The reduction percentages were calculated by equation of Henderson and Tilton (1955).

Results:-
At beginning; the pre-count refers to the mean of the population density /20 leaves before the release. While level (5) refers to level of the release of spiders at rate 5 spiders for 1 bit. Meanwhile level (10) refers to level of the release of spiders at rate 10 spiders for 1 bit. And the (P.D.) means average of the population density /20 leaves of the pest.
As showed in table (1)

Dissection:-
It's for sure that the spiders strike the larvae, as shown in this study in table (1), where they seemed as they tracked the larvae until they almost finished in the third week. But it was not certainly that spiders were the only cause of the disappearance of larvae, where the infection appeared again in the fourth week and the adult of S.littoralis were seen on the walls of greenhouse.
The disappearance of larvae may be associated with the duration of the life cycle of the pest, which can be completed in about 25 days, and lasted the pupa stage in the soil (Espinosa, A. and A.C. Hodges, 2012). Additions that experiment were conducted during (22/7-19/8).
When the larvae began to appear and population density became high again, the larvae -which were eaten -existed on the leaves (i.e., the spiders Suck the larvae and left them dead on the leaves). Then the larvae disappeared again.
Based on that; the fields which have no spiders were attacked by pests, contrary to the fields which spiders had been removed, they had higher pests more than those in which spiders remained (Riechert, S.E. and K. Lawrence., 1997) Meanwhile it cannot be said that spiders alone were unique in restoring ecological balance. There are about 169 vital enemies that we can preserve. Jianjun, X. et al. (1999).