THE SPIDERS OF A CITRUS GROVE IN ISRAEL AND THEIR ROLE AS BIOCONTROL AGENTS OF CEROPLASTES-FLORIDENSIS [HOMOPTERA, COCCIDAE]

A 12 month survey was carried out of the spider population in a commercial citrus grove at Kibbutz Afeq in Northern Israel. The spiders collected from grapefruit foliage and ground cover were identified: young stages were reared to maturity and then identified. Chiracanthium mildei L. Koch represented 52% of all spiders captured during the year and Theridion sp. accounted for 34%. In the undercover, Gnaphosidae spiders represented 43% of the total spiders captured in pitfall traps and Lycosidae 35%. A field experiment was carried out to evaluate the effectiveness of spiders in biological control of the scale Ceroplastes floridensis Mask. in the citrus ecosystem. Wherever spiders were undisturbed on tree branches, populations of C. floridensis were not able to develop to a level sufficient to cause economic damage. The increase in the number of scales was minimal:from 47 initially to 56. There was no damage to leaves nor was honeydew or sooty mold observed. During the same time period, on the 3 branches from which spiders had been eliminated, the number of scales increased seven-fold from 44 to 309. Leaves were heavily infested with sooty mold fungi that developed on the honeydew produced by the scales.