Journal of Entomological Society of Iran
Year:2006 | Volume:25 | Issue:2|Papers Count:11

The Asiatic citrus psyllid, Diaphorina citri Kuwayama (Hom: Psyllidae), is one of the most important pests on citrus in tropical and subtropical Asia. It was detected in Iran during the recent years and distributed in some parts of Hormozgan and Sistan-Baluchestan provinces. During the survey carried out to determine natural enemies of this psyllid, a nymphal parasitoid wasp was identified as Psyllaephagus stenopsyllae (Tachikawa). This is the first report of P. stenopsyllae in Iran. This species has previously been reported from Taiwan, China and Japan as a parasitoid of Stenopsylla nigricornis Kuwayama and Trioza zyzygii Li & Yong (Hom: Psyllidae).

Two species of Tachinidae, Masicera sphingivora (Robineau & Desvoidy) and Bithia glirina (Rondani), were collected from pupae and larvae of Hyles euphorbiae (L.) (Lep.: Sphingidae) and Chamaesphecia schizoceriformis Kolenati (Lep.: Sesiidae) respectively. Masicera sphingivora belongs to the subfamily Exoristinae and has mostly been reared from the larvae of Sphingidae, especially the genus Hyles Hübner, as well as different species of Noctuidae, Lymantriidae, Lasiocampidae and Nymphalidae. Bithia glirina is a very rare species belonging to the subfamily Tachininae and has been reported as a parasitoid of species of Chamaesphecia Spuler. These tachinid species are newly recorded from Iran.

Six genera and 10 species from the family Ichneumonidae, viz. Synechocryptus boevi Brulle, Aritranis bellosa Curtis, Mesostenus grammicus Gravenhorst, Phygadeuton trichops Thomson, Sphecophaga vesparum Curtis, Trychosis legator Thumberg, Cryptus italicus Gravenhorst, C. spinosus Gravenhorst, C. medius Szeplegeti and C. tuberculatus Gravenhorst are newly recorded from Iran. These species were collected from Shiraz and vicinity and the identification confirmed by Jussila, Finland, University of Turku. All ten species belong to the subfamily Cryptinae. From the seven genera mentioned above, only Cryptus Fabricius has already been recorded from Iran.

Three genera and species from the family Ichneumonidae, viz. Diadegma majale Gravenhorst, Campoletis thomsoni Roman and Hyposoter notatus Gravenhorst are newly recorded from Iran. These species were collected from Shiraz and vicinity and the identification confirmed by Jussila, Finland, University of Turku. The members of the subfamily Campopleginae to which these three species belong are known as parasitoids of lepidopteran and dipteran larvae.

Scale insect specimens collected on Hordeum sp. (Poaceae) dated 24. V. 2003 in Khorram Abad, Lorestan province was identified as Exaeretopus tritici Williams. This species, which the genus and species is newly recorded from Iran, is related to E. harpazi Ben- Dov, differing mainly in the number of the stigmatic setae and extension of paraopercular pores.

In the current study some information is presented about the distribution and associations between alfalfa aphids and their parasitoids in different regions in 11 provinces of Iran, as well as identification key to the parasitoids. The main aphids were Therioaphis trifolii maculata (Buckton) and Acyrthosiphon pisum (Harris) followed by Aphis craccivora Koch and Acyrthosiphon kondoi Shinji. The distribution pattern of these aphids showed a discrepancy in different regions. Therioaphis trifolii maculata was almost distributed in all studied areas, but A. craccivora mostly distributed in lower regions including the deserts of the east and central parts of Iran. Acyrthosiphon pisum and A. kondoi were mainly occurred inhigher altitude regions.Trioxys complanatus Quilis and Praon exsoletum (Nees) were found to be specific parasitoids of T.trifolii maculata, and collected, with a few exceptions, in all studied regions. The species of Acyrthosiphon were mainly attacked by Aphidius ervi Haliday followed by A. smithi Sharma & Subba Rao and A. eadyi Stary, Gonzalez & Hall. Lysiphlebus fabarum (Marshall) was the common parasitoid of A. craccivora, but Ephedrus persicae Froggatt locally found to show host specificity on this aphid. Praon volucre (Haliday) was occasionally found to attack A. pisum and A. craccivora, but the other parasitoids including Aphidius colemani Viereck, Lysiphlebus confusus Tremblay & Eady and Diaeretiella rapae (McIntosh) were only reared from A. craccivora. Considering the occurrence of alfalfa aphids together with their parasitoids in almost all studied areas, it seems that more attention should be paid to the parasitoids of alfalfa aphids, especially the specific ones, along with other control methods in an integrated pest management programme.

Chaitophorus populeti (Panzer) is considered as an important pest of Populus Alba in the Chaharmahal-Bakhtiari province. During 2000-2001, the population fluctuation of the aphid and its predators was studied in four different regions including Juneghan, Zayandeh-Rood, Baba-Heidar and Cheshmeh-Ali. Population sampling was carried out weekly in these regions by cutting four branches (length 30 cm) from four trees considering the four main geographical directions. Then the aphids and natural enemies in each branch were counted. The results indicated that the peak of aphid populations occurred on the first half of June of 2000 and second half of June of 2001, with the mean of 165 ± 8.8 and 184±6.6 aphids per branch respectively. In these two years, the aphid population densities, as well as population densities in the four geographical directions were not statistically different (p>0/05). The predators of the aphid collected in the four studied regions included four species of ladybirds, one lacewing species, two species of bugs and one fly species. There was a significant correlation between the aphid population and its predators. The calculated determination coefficient (R2) between the aphid population and ladybirds, and between the aphid population and other predators were 0.78 and 0.48 respectively, in 2000; and 0.88 and 0.84 respectively, in 2001. In both years, the determination coefficient between the aphid population and ladybirds was more than that of between the aphid population and other predators in the four regions.

Insecticide application is necessary for controlling Trialeurodes vaporariorum (Westwood) in integrated pest management, so if they don't have any side effects on Encarsia Formosa Gahan, they can be used as alternatives for common insecticides. Therefore an experiment was conducted to investigate the effects of buprofezin and pyriproxyfen (IGRs) compared with fenpropathrin (pyrethroid) on E. formosa. Bean leaves with parasitoid pupae were immersed in insecticide solution with recommended concentration. In another experiment adult insects were released on a leaf disk after immersion in insecticide solution, thereafter, different parameters such as adult longevity, daily fecundity rate and percentage of egg hatching were recorded with demographic toxicology. These experiment was done under temperature of 26±1 oC, 60% RH and photoperiod of 16: 8 (L: D). Pyriproxyfen and fenpropathrin reduced adult emergence by 27.5% and 67.8 % respectively, while buprofezin (3.8%) didn't have a considerable lethal effect on parasitoid pupae. Buprofezin and pyriproxyfen didn't have lethal effect on adult parasitoids while fenpropathrin caused 100% mortality in the recommended concentration. Mean fecundity and longevity showed no significant difference in buprofezin (59.6 ± 5.4) (14.5 ± 1.0) and pyriproxyfen (62.5 ± 4.8) (15.0 ± 0.9) compared with the control (64.5 ± 5.3) (15.5 ± 0.8), while fenprpathrin (20.4 ± 2.4) (6.6 ± 0.6) reduced these parameters. Egg hatch rate showed a little reduction in buprofezin and pyriproxyfen compared with the control. In summery we can conclude that buprofezin and pyriproxyfen are relatively safe for E. formosa and they can probably be used for integrated control of this pest.

Effects of gamma radiation doses on Callosobruchus maculatus (F.) were studied. In this study different doses including 0, 20, 35, 50, 60 and 70 Gy were used in the pupal stage and emerged adults were separated before mating and crossed in treatments including: normal male × normal female, normal male × irradiated female, irradiated male × normal female and irradiated male × irradiated female.Comparing means (Duncan,s test, 0.05) showed that in 20 Gy, all treatments had significant difference, except normal male × normal female and normal male × irradiated female. In 35 Gy, all treatments had significant difference. The most sterility was observed in irradiated male × irradiated female and it was not significantly different with irradiated male × normal female. In 50 Gy, treatments which contained irradiated males or irradiated females had significant difference with treatments containing normal males and females. In 60 and 70 Gy, hatchability percentage in the next generation, both for sterile males and sterile females, reduced population significantly. Therefore, 60 to 70 Gy induce sterility in this insect.Sterile insect release to a normal population was studied in three cases including: sterile male, sterile female and sterile male and female releases. Results indicated that sterile female release had no effect on reducing population in the next generation. Sterile male release and sterile male and female release had identical effects. As a regard to the fact that separating males and females is difficult and time consuming, therefore, it seems that sterile male and female release in the ratio of 10:10:1:1 (irradiated male × irradiated female × normal male × normal female) cause the best result in population reduction in the next generation.

Onion thrips, Thrips tabaci Lindeman, is one of the most important pests of vegetables and ornamentals all over the world. Its role has been proved in the transmission of different viruses to several plants. In this study, life history parameters of T. tabaci were calculated on three host plants, cucumber, sweet pepper and eggplant. Experiments were conducted at 25 ± 1oC, 60 ± 10% R.H. and photoperiod of 16:8 (L: D) hours. The results showed that host plants affect life history of onion thrips significantly.Intrinsic rate of population increase (rm) was 0.296, 0.158 and 0.234 female on female per day on cucumber, sweet pepper and eggplant respectively. Other parameters like ë (finite rate of increase) were 1.334, 1.171and 1.264; T (mean generation time) were 14.879, 19.092 and 16.779; DT (doubling time( were 2.343, 4.384 and 2.956 days. Finally, R0 (net reproductive rate) was 81.581, 20.461 and 51.141 female/female in one generation. With regard to highly significant effect of host plants on life history parameters of onion thrips, it is probable that this problem could be used for control of onion thrips on sweet pepper more effectively than on cucumber and eggplant.

Crob Moth, Ectomyelois ceratoniae is the most important pest of pomegranate in Iran. During 2001-2002, the growth period of this species was studied on three artificial, semi-artificial and natural diets in the laboratory condition, 27 ± 1°C, 75 ± 5% R.H. and photoperiod of 16: 8 (L: D) hours. The components of these diets were: 1- soybean pert 30 gr., soybean oil 5 ml, yeast 3 gr., formaldehyde 1 ml., beetroot molasses 20 ml., antioxidant 1 gr., pomegranate fruit (oven-dried) 20 gr. and water 50 ml., 2- soybean pert 30 gr., soybean oil 5 ml., yeast 3 gr., formaldehyde 1 ml., beetroot molasses 20 ml., NaCl 1 gr., FeSo4 2.5 gr., rice bran 10 gr., antioxidant 1 gr., wheat germ 10 gr. and water 50 ml., 3- soybean pert 30 gr., soybean oil 5 ml., yeast 3 gr., formaldehyde 1 ml., beetroot molasses 20 ml., antioxidant 1 gr., pomegranate fruit (freeze-dried) 20 gr. and water 50 ml., and 4- pomegranate (the natural diet of the pest used as the control treatment). The shortest period of larval, pupal and adult stages was on the diet 1, and the longest period of these stages was on the diet 2. The shortest and longest adult longevity was seen on the diets 2 and 1 respectively. The lowest and highest sex ratios were recorded for the diets 1 and 2 respectively. The larvae were successfully reared for five generations on the diet 1, which the percentage of fertile females and the number of eggs increased considerably in the fifth generation.