Mahmood Alichi, Ali Asghar Ahmadi,
Volume 3, Issue 1 (spring 1999)
Abstract
The effectiveness of Buprofezin (40% SC) and Pyriproxifen (10% EC) on the mortality of nymphal stages and fecundity of cottony cushion scale was investigated under glasshouse conditions. The LC50 of IGRs was also determined for the first nymphal stage. Two applications were conducted at intervals of 1 day prior to introduction of crawlers and 42 days after infestation. The results indicated that Buprofezin was superior to Pyriproxifen in suppressing the growth and development of crawlers. The mortality of first instars was determined 28 days after the first application. Although the total mortality of second instars due to Pyriproxifen was higher than that by Buprofezin, but the cummulative mortality of 1000 ppm treatment was estimated to be 100% in both experiments after 42 days. The effect of Buprofezin on incomplete molting of nymphs and its ovicidal activity showed a decreasing rate in third instar nymphs survival and fecundity of cottony cushion scale in relation to different concentrations of the IGRs, but it never reached 100%. Meanwhile the 1000 ppm concentration of Pyriproxifen in the same treatments brought about complete mortality to third instar nymphs and inhibited adult and egg formation due to imbalanced juvenile hormone activity. However in 1 ppm concentration of Pyriproxifen, a noticeable increase in fecundity of cottony cushion scale was observed.
M. Alichi, P. Shishehbor, M.s. Mossadegh, E. Soleiman Nejadian,
Volume 12, Issue 45 (fall 2008)
Abstract
In a study of aphids and their parasitoids in wheat fields of Shiraz region, the species composition, distribution and seasonal dynamics of the dominant species were monitored during 2004-5.Collections were made from 1-3 hectare fields in 10 locations within 50 Km radius around Shiraz city. Species density was estimated by counting individuals present on 40 winter wheat tillers taken at random along 2 transects 5 m apart in the fields. Eight aphid and 3 parasitoid species were identified through this survey. Rhopalosiphum padi (L.) and Metopolophium dirhodum (Wlk.) with relative abundances of 33.94 and 31.33%, Aphidius rhopalosipi De Stefani-Perez and Praon volucre (Hal.) with relative abundances of 55.53 and 39.90%, were the dominant species of aphids and parasitoids, respectively. Seasonal dynamics of the above species were also studied in Badjgah, located 15 Km north of Shiraz city. Peak populations of the dominant aphids occurred between late May and first of June 2004-5, and those of parasitoids were seen 1-3 weeks later. A comparison between seasonal parasitism of the dominant parasitoids showed significant preferences of A. rhopalosiphi on R. padi, and P. volucre on M. dirhodum. Since the total parasitism of both wasps was nearly 30% of the two aphid hosts, attention should be paid to chemical control programs of wheat pests (such as Sunn pest) so that it does not disturb the efficiency of the aphid parasitoids.
