نشریه نامه انجمن حشره شناسی ایران
سال سی و دوم شماره 1 (پیاپی 50، تابستان 1391)

Biological and predatory characteristics of Andrallus spinidens (F.) on fourth instar larvae of Egyptian cotton leafworm، Spodoptera littoralis (Bois.)، were investigated، under laboratory condition، at 25 ± 1°C، 60 ± 5% RH and a photoperiod of 16:8 L: D h. The analysis was based on an age-stage، two-sex life table. The intrinsic rate of increase (rm)، finite rate of increase (λ)، net reproductive rate (R0)، gross reproductive rate (GRR) and mean generation time (T) of A. spinidens on S. littoralis were 0. 0821 day-1، 1. 0821 day-1، 102. 77 offspring، 192. 61 eggs and 58. 68 day، respectively. The mean reproductive value of A. spinidens was estimated as 342. 58 ± 48. 18 eggs per female. The intrinsic birth rate (b) and intrinsic death rate (d) for A. spinidens on S. littoralis were 0. 0894 and 0. 0073، respectively. The first stage nymphs of A. spinidens live only on water but the second، third and fourth stage nymphs fed on 12. 22، 26. 22 and 41. 28 of S. littoralis larvae، respectively. The fifth stage nymphs were more voracious and preyed on more than 70% of the larvae (94. 36). At the adult stage، both male and female of A. spinidens were able to kill up to 85% of the larvae. In conclusion، the results prove that this predator pentatomid bug can be used as an efficient biological control agent against the noctuid pest، S. littoralis.

The prey stage preferences of the second and third instar larvae of syrphid fly species Eupeodes corollae (Fabricius) on different nymphal instars of Brevicoryne brassicae (L.) were studied in no-choice and choice conditions (25 ± 2°C، 65 ± 5% R. H. and 16L: 8D photoperiod). In no-choice test، the second and third instar larvae of E. corollae were separately supplied with a total of 40 nymphal instars of B. brassicae. In choice test، 10 nymphs from all nymphal stages of B. brassicae were simultaneously offered to the second and third instar larvae of E. corollae. In no-choice test، the highest larval feeding of the second (25. 00 ± 2. 61) and third (38. 2 ± 0. 58) instar larvae of E. corollae were observed on the first and second nymphal instars of B. brassicae، respectively. However، there were not significant differences in their feeding behavior on the first to third nymphal instars of B. brassicae. In choice test، the highest feeding rate of second instar larvae was 5. 00 ±0. 84 aphids on third instar nymphs of B. brassicae. No significant differences were observed in feeding rates of the predator’s third instar larvae. Switching behavior was not observed for the third instar larvae of E. corollae، while different second: third instar ratio found to be 10:50، 20:40، 30:30، 40:20 and 50:10.

Common pistachio psylla، Agonoscena pistaciae Burckhardt & Lauterer، is the most economically important species among the psyllid pests of pistachio in Iran. Hence، the possibility of using nonchemical control methods against A. pistaciae and the existence of its natural enemies need to be investigated. The spotted amber ladybird، Hippodamia variegata (Goeze)، is one of the most effective predators in pistachio orchards. It is a highly polyphagous coccinellid that preys mainly on aphid and psyllid pests of pistachio trees. This study is intended to improve the knowledge about the predation capacity of A. pistaciae. The experiment was conducted under laboratory conditions of 25oC and 30oC، 55 ± 5 RH and 16:8 L: D. Logistic regression was used to determine the type of functional response and nonlinear regression calculated the parameters of the rate of searching efficiency (a) and handling time (Th). The functional response on different density of prey at both temperatures was type II. The attack rate and handling time were 0. 088 ± 0. 012 h-1 and 0. 0647 ± 0. 011 h at 25ºC and 0. 195 ± 0. 031 h-1 and 0. 0698 ± 0. 056 h at 30ºC، respectively. The density and temperature affected the predation rate significantly. The data suggests that the H. variegata is a viable biological agent against A. pistaciae.

The coleopteran family Carabidae is one of the most abundant and diverse generalist predators in agroecosystems، playing an important role in maintaining pest populations below economic threshold. Using pitfall traps، carabid beetle specimens were collected from olive، peach، and mixed peach-olive orchards in Azadshahr region، east of Golestan province in 2009-2010. Two indices of Shannon-Weaver and Margalef were employed to evaluate the diversity and structure of the beetle communities. The species richness of ground beetles was 31، 19، and 12 species in mixed olive-peach، peach، and olive orchards; and the dominant species were Harpalus rufipes (De Geer)، H. rufipes and Calathus peltatus Kolenati، respectively. The values of Brillouin’s index of evenness and Shannon’s index of diversity were calculated as 0. 46 ± 0. 04، 0. 51 ± 0. 07، 0. 65 ± 0. 13 and 1. 59 ± 0. 18، 1. 52 ± 0. 21، 1. 57 ± 0. 23، respectively. There was no significant difference in overall Shannon’s indices، but the evenness of ground beetles in olive orchards was significantly higher than other orchards. The community of ground beetles on orchard margins was found to be more diverse than central parts. The high diversity of ground beetles in orchards of this region underlines their role in protecting the diversity of vegetations around or within the orchards and also efficiently keeping the populations of economic orchard pests in check throughout the season.

The susceptibility of the ladybird Chilocorus bipustulatus (L.) to different concentrations (0. 5%، 1. 0% and 1. 5%) of volk oil was studied. The 0. 5% concentration was found to be harmless، while the 1. 0% and 1. 5% concentrations were slightly harmful. The adult males and females as well as the 3rd instar larvae of ladybird''s mean feeding on Aonidiella orientalis (Newstead) were about 6. 15، 6. 37 and 7. 09 numbers in 24 hours respectively. The simultaneous application of volk oil and ladybird''s release is recommended for an effective control of A. orientalis.

The herb gall wasp، Aylax hypecoi Trotter، is recorded as new for the Iranian cinipid fauna. The specimens were collected from induced galls on fruit-like pods of Hypecoum pendulum L. (Papaveraceae) in Urmia region. The A. hypecoi-H. pendulum association is also newly recorded. Notes on diagnostic characters، biology and associated parasitoids of A. hypecoi are given.

This paper reports the occurrence of the hymenoterous parasitoids of the beet moth، Scrobipalpa ocellatella Boyd larvae in Iran for the first time. Two braconid species of Microchelonus subcontractus Abdinbekova and Bracon intercessor Nees were collected from the larvae of S. ocellatella in the sugar beet fields located in Ray، the southern district of Tehran. These parasitoids are belonging to the subfamilies Cheloninae and Braconinae، respectively.

Fourteen accessions and cultivars of Lycopersicon spp. were studied to evaluate their resistance to two-spotted spider mite، Tetranychus urticae Koch، under laboratory and greenhouse conditions. In vitro studies were carried out using thumbtack and leaf disk bioassays. Lycopersicon hirsutum and L. pennellii accessions supported more mites on the tack. The highest number of eggs (5. 15 ± 0. 48 eggs / ♀ / d) was recorded on L. pimpinellifolium LA2533 and the lowest number (0 egg / ♀ / d) was recorded on L. hirsutum and L. pennellii accessions. The highest mite mortality and lowest damage score occurred on the leaf disks of L. pennellii and L. hirsutum accessions that were strikingly in contrast to our observations on L. esculentum varieties (Nandi and Sankranthi). The developmental time of the mite was longest (8. 61 ± 0. 18 days) on leaf disks of L. esculentum NDTVR-73 and shortest (7. 18 ± 0. 51 days) on L. pimpinellifolium LA2533. In the greenhouse، the mite was unable to establish on L. hirsutum and L. pennellii accessions. Amongst the rest، Nandi and Sankranthi accessions/cultivars supported the highest، while NDTVR-73 supported the lowest mite population. The highest and lowest density of type VI glandular trichomes were recorded on L. esculentum NDTVR-73 (67. 33 ± 6. 34 trichomes/mm²) and L. pennellii LA2963 (0. 79 ± 0. 15 trichomes/mm²)، respectively. No relation was found between density of type VI trichomes and resistance to the mite. Type IV glandular trichomes were observed only on the foliages of L. hirsutum and L. pennellii. A positive relation exists between the density of type IV glandular trichomes and resistance to the mite.

Life table parameters of the beet armyworm، Spodoptera exigua (Hübner)، on four sugar beet cultivars (Renger، FD0005، Dorothea and Shirin) were studied in laboratory at 27 ± 1°C، 60 ± 5% RH and a photoperiod of 16L: 8D hours. The larvae successfully developed on all cultivars. The shortest and longest total developmental time were recorded on FD0005 and Renger، respectively. The development index (D. I.) of larval period varied from 4. 90 to 5. 97 on Renger and Shirin، respectively. The life expectancy (ex) was 26. 94، 31. 39، 30. 51 and 30. 16 days on the cultivars respectively at the beginning of life. Life table entropy (H) indicated the survival schedule of S. exigua was convex (type I) on all sugar beet cultivars. The gross fecundity ranged from 1499. 93 to 2034. 67 eggs on Dorothea and FD0005، respectively. The lowest value of net reproductive rate (R0) was recorded on Renger (253. 59 females per female per generation). The intrinsic rate of increase (rm) ranged from 0. 2235 on Renger to 0. 2309 day–1 on FD0005. The mean generation time (T) was found to be significantly different on sugar beet cultivars. Fitting adult survival data to Weibull frequency distribution indicated that the adult survival curve was type I on all cultivars suggesting that the mortality was higher in old individuals. The cultivar Renger was less suitable in comparison with other cultivars in the laboratory. These results provided important information on the effect of four commercial sugar beet cultivars on population growth potential of S. exigua.

The leaf-miner fly، Liriomyza sativae (Blanchard)، is one of the major insect pests of vegetable crops in Iran and other countries. To determine the toxicity (LC50) of bioinsecticides abamectin 1. 8% EC، cyromazine 75% WP and spinosad 24% SC against L. sativae، bioassay was done on its larval and adult stages under 25 ± 1°C، 65 ± 5% R. H. and a photoperiod of 16:8 (L: D). The LC50 values found to be 1. 5، 1. 8، 14. 3 ppm for abamectin، 34. 8، 38. 4، 1295 ppm for cyromazine and 4. 4، 12. 1، 13. 7 ppm for spinosad against the first and last larval stages as well as the adults of L. sativae، respectively. The toxicity of the insecticides on the larval stages was higher than on adults. Using a mixture of petroleum oil، as a synergist، and the insecticides significantly increased the mortality of the first instar larvae. The results indicated that cyromazine is ineffective for the control of adults، while it is proved to be effective against the leaf-miner''s larval stages. It is found that abamectin and spinosad are more efficient insecticides than cyromazine for the control of all developmental and adult stages of L. sativae.