Journal of Entomological Society of Iran
Year:2002 | Volume:22 | Issue:1|Papers Count:7

The lady beetle Oenopia conglobata L. is one of the most active predators on forest trees and various crops reported from Iran and around the world. In order to study the effect of temperathre on different developmental stages (egg, larval instar, prepupa and pupa) of O. conglobata, 30 specimens of each stages were selected and separately kept in petri dishes. The eggs and the larvae were daily visited for the determination of hatching time and duration of different stages of development. Six pairs of lady beetle (of the same age and generation) for the rate determination of oviposition inside a incubator. All the experiments were performed at temperatures of 20, 25 and 30°C with 65±5 %RH, 14 hL and 10 hL periods feeding upon Chaitophorus populeti (Panz). The results of the experiments showed that duration of developmental period of lady beetle O. conglobata from egg to adult decreased with increasing temperature from 20 to 30°C. The results showed except for preoviposition period, the increase in temperature from 20 to 30°C increased the daily egg laying amount, total egg laid and the egg laying period.

The biology of Hippodamia variegata was studied under laboratory conditions during 2000-2001. Adult Coccinellids collected in alfalfa field in Rostam - Abad region were transferred to laboratory. With the use of obtained duration of lady beetle development stages at four temperaturs (20, 25, 30, 35°C) and 65±5% RH and 16: 8 (L: D) photoperiod were investigated. The mean duration of development times of H. variegata from egg to adult at temperatures of 20, 25, 30 and 35°C feeding on,,4phis nerii were 28.88, 21.04,13.08 and 10. 30 days respectively. The maximum and minimum hatching percent were observed at 25 and 35°C respectively. The thermal development threshold of egg, larval stages, pre pupa, pupa and egg to adult, were 11. 16, 13.4, 12.96, 13.48 and 12. 76°C respectively. The thermal development threshold ranged from 11. 16 for eggs to 14.33 for 3rd instar larve with heat unit requirements of 42 and 25. 75 degree days, respectively and that for egg-adult was 230. 13. The average of egg laying duration was 52±2.27 days and daily oviposition mean for each female was 43.77±2.51 eggs. e daily egg laying amount, total egg laid and the egg laying period.

The results of a two year study (1997-1998) on the ecology of egg parasitoids of the sunn pest (Eurygaster intercepts Put.) in Varamin area, revealed that egg masses of sunn pest are attacked by four parasitoid species, Trissolcus grandis Thomson, T. vassilievi: Mayr, T. semistriatus Nees. and T. basalis Whollaston all belonging to the family Scelionidae (Hym.: Proctotrupoidea). Of these, the most effective and widespread parasitoid appears to be T. grandis. In Varamin, egg laying period of sunn pest starts from late April to May. The seasonal parasitism pattern of T. grandis the T. vassilievi had strong synchrony with the host’s egg population but T. simistriatus occurred only in peak of egg laying period and parasitism of T. basalis did not showed any specific pattern. The overall parasitoids impact on the sunn pest population was 22.3% in 1997 and 23.43% in 1998. Egg parasitoids of sunn pest regulate the host population in a density-dependent manner (Temporal density-dependence is positive and weak but spatial density dependene is positive and strong).

Fig spider mite (Eotetranychus hirsti) is a serious pest of figs in Iran and other fig growing areas in the world. Population fluctuation (eggs and active stages) of fig spider mite have been investigated on eleven fig varieties include: yellow indigenous, Saveh yellow and Black indigenous, Varamine black, Onion yellow, wild fig, Garmsar Morabai, Siljerd yellow and American, in Saveh region during 2000-2001. Eggs and active stages of the mite were counted using a four square centimeter quadrate placed on the lower surface of host leaf. A randomized block design with four replication and a fort nightly interval sampling was used (May to mid Nov.) Analysis of variance were carried out on collected data and differences of mite population observed by Duncan’s multiple range test on fig varieties. Maximum mean of eggs 6.08,5.05 and active stages 31.87, 27.62 recorded for Wild fig variety in both years which statistically found in the group of (a) and was more susceptible in comparison to other varieties followed by Garmsar Morabai (ab) and Siljerd yellow (be). Whereas, minimum of 0.002 and 0.02 egg were recorded on Varamine black in both years and for active stages 0.032 and 0.36 mite recorded on Yellow indigenous and Varamin black on both years respectively.

Two species of pink stem borers cause serious damage on their hosts in Iran. Chemical control of them caused pest resurgence. Their egg parasitoid was distinguished as Platytelenomus hylas Nixon (Hym.: Scelionidae). Studies on rearing and releasing of this parasitoid, for biocontrol purpose, indicated that the wasps have a high spescialization and for multiplication it is necessary to use their natural hosts. In this investigation two semi-artificial and three natural diets (Sorghum, Corn and Sugarcane stems) for rearing in Laboratory conditions were used. On each diet mean of larval period, pupation percentage, means of male and female pupal weight, mean of pupal period and percentage of emerged adult were evaluated. Finally fertility rate of emerging adults from each diet were compared by CRD experiment. In vivo rearing of species of the stem borers have no success on semi-artificial diets whereas rearing on natural hosts were more efficiently. Survival rate and quality of Scretica fed on sorghum were higher than S.nonagrioides botanephaga whereas individual of the latter could be reared more successfully on corn. Comparison of food effect on adult fertility indicated that food quality have no effect on fertility of S cretica whereas individuals of the latter that reared on corn and sorghum in 5% probability level have a significant difference with sugarcane and moths have laid more eggs.