فصلنامه تحقیقات حشره شناسی
سال چهارم شماره 1 (پیاپی 13، بهار 1391)

Benthic macroinvertebrate species are differentially sensitive to many biotic and abiotic factors in their environment. The field biotic index is based on family level identification of water arthropods، amphipods and isopods. An interest in environmental quality is one of the major reasons for the study of aquatic insects. The idea of using the aquatic insect community to “indicate” the degree of purity or pollution of a body of water is over half a century old. It is based on the concept of indicator organisms and tolerance levels. During 2010-2011 studies were carried out on the field biotic index of lake of Doroodzan dam in Fars province using aquatic insects fauna. A total of 23 families were collected and identified in 12 habitat codes of the lake. Aquatic insects are given a numerical pollution tolerance score ranging from 0 to 10. The value is based on field and laboratory responses of these organisms toward organic pollution. Zero taxa are extremelyintolerant to low dissolved oxygen; taxa with score of 2 through 9 are tolerant to varying degrees; taxa which can survive great amounts of pollution are scored 10. In this survey، biotic index of lake of Doroodzan dam was 3. 92 which places in the rank of very good during this survey.

Cryptolaemus montrouzieri Mulsant is one of the important predators of the citrus mealybug، Planococcus citri (Risso). This study was carried out to investigate the effects of Diazinon and Imidaclopride in direct (spraying) and indirect methods (prey treated with insecticide) on larvae and adults of the ladybird. The experiment was conducted in 5 treatments and 4 replications under 25±1° C and 65±5% RH. Each replicate included 25 larvae and adults. Mortalities were recorded 72 h after treatment. The results indicated that Diazinon and Imidaclopride were moderate toxic (33-66%) to adult stage of C. montrouzieri (according to IOBC standard method) in direct spraying method The corrected mortalities of fourth instar larvae of C. montrouzieri by field recommended doses were lower than 30% (slightly harmful). The corrected mortalities of pesticides with different dosages on fourth instar larvae were lower than 10% (harmless pesticide). In other experiment، the realative toxicity of Diazinon on adult stage of C. montrouzieri in indirect method (prey treated with insecticide) was ranged between (66-100%) and Imidaclopride which was lower than 30% (slightly harmful). The corrected mortalities of pesticide induced by different dosages varied dosages on adult stage of C. montrouzieri was lower than 20% (harmless). Relative toxicity of tested pesticides on fourth instar larvae C. was lower than 20% (harmless).

The effect of drought stress on damage of safflower fly، Acanthophilus helianthi Rossi (Dip.، Tephritidae) was compared on three cultivars of safflower، Carthamus tinctorius L. by an experiment in split plot arrangement in completely randomized design in 2011. Where levels of irrigation including complete irrigation during whole growing season (S1)، cutting irrigation at flowering stage (S2) and cease irrigation at heading stage (S3) as main plot، and safflower cultivars including Goldasht، Padideh and C44 as sub-plot. Percentage of infested boll and seed weight were sampled in the experimental plots. Results indicated a significant difference at 1% level in percentage of infested bolls among drought stresses. Also، percentage of infested boll and 1000- seed weight in healthy boll had significant difference among cultivars. The highest and lowest percentage of infested boll belonged to S3 (69. 44%) and S2 (65. 94)، respectively. The highest and lowest percentage of infested boll belonged to Padideh cultivar (68. 05%) and Goldasht cultivar (50. 09%). Results showed that in non-stress conditions، Goldasht has the best growth and resistance to safflower fly، while in drought stress conditions، Padideh is the best alternative but overall Goldasht was cultivar recognized as the most resistant in among of three cultivars. In this cultivar، damage of some seeds in a boll increased 1000-seed weight in healthy seed of the boll because 1000-seed weight in infested boll is more than healthy 1000-seed weight in infested boll. It is probable that compensation phenomenon in Goldasht cultivar appears against safflower fly damage.

The Jasmine moth Palpita unionalis Hubner (Lep.، Pyralidae) is one of the most important pests of plants from Oleaceae، such as privet (Ligustrum ovalifolium Hassk) and olive (Olea europea L.). This insect has been introduced to Iran in recent years. Therefore، it needs extensive researches according to its new ecological conditions. In this regard، the plant host preference of the pest was studied to find an alternative plant host for rearing the jasmine moth. The biological parameters of this moth compared when reared on the two plant hosts (north of Iran). Pupae of the pest were collected from the trees and nurseries of olive at Tarom region. Adults emerged were transferred to growth chamber for rearing at the conditions of 25±0. 5 °C، RH %65±5 and 12L: 12D. Biological parameters such as number and period of generation، larval feeding rate، larval development time and mortality، sex ratio and adults longevity were compared on olive and privet. The pest has five instars on two hosts but larval duration is shorter on privet. Also it feeds much more quantity of leaves of privet. The rate of mortalities were not different significantly. Thisinsect produced 8 and 10 complete generations on olive and privet، respectively. According to theaccomplished studies، host suitability was similar، but the privet is more available and inexpensive than olive for laboratory rearing of jasmine moth.

The study was done during 2010-2011 to investigate the integrated effects of diatomaceous earth and three genotypes of corn on adults mortality of red flour beetle Tribolium costaneum in laboratory conditions (27°C، 60±5% RH and dark). The adults of red flour beetle fed with three concentrations of diatomaceous earth (0. 5، 1 and 1. 5 gr/kg) on three genotypes of corn in 4 replications. The mortality of T. castaneum was recorded after 2، 7 and 14 days and compared with control. Results showed that there was significant differences between genotypes and different concentration of diatomaceous earth. The comparison of means showed that 1 gr/kg concentration and KE1728/8 genotype of corn were the best treatment separately. Results of integrated effects showed that percentage of mortality hada significant difference only on 14th days. So 0. 5 gr/kg concentration of diatomaceous earth and KE720/12 genotype are recommended as the best integration.

The effect of sublethal doses of two pesticides، Ethion and Imidacloprid on reproductive parameters of Cryptolaemus montrouzieri Mulsant (Col.، Coccinellidae) were investigated at constant laboratory condition. The insects were exposed to LC30 concentration of the pesticides during first 24 hours of their life. The amounts of LC30 and LC50 were respectively 244. 58 and 385. for Ethion، and 130. 83 and 221. 45 ppm for Imidacloprid. The mean life span of adults in control was higher (41. 2 days) than in treatments of Ethion (31. 1 days) and Imidacloprid (26. 7 days). The whole period of females'' pre puberty in control and treatment with Ethion and Imidacloprid were record 30. 9، 33. 9، 36. 9 respectively. Sex ratio was calculated respectively 74. 33، 54، and 46. 67. Net fertility rate in control and treatment with Ethion and Imidacloprid were respectively record 449. 48، 248. 5، 182. 45 eggs and net breeding rate were 394. 6، 224. 4، 166. 7 eggs. The gross rates of hatching were calculated 0. 87، 0. 90 and 0. 90 eggs. Mean egg per day in control and Ethion and Imidacloprid were 11. 8، 9. 6 and 9. 5 eggs respectively. Intrinsic rate of natural increase (rm) in control and treatments were 0. 13، 0. 10، 0. 09 female/ female/ day respectively. These results undicate that the sublethal doses of Ethion and Imidacloprid decrease the biological parameters of the coccineid.

In the present research، the influence of 5 diets e. g. pistachio psyllid nymph، the cowpea aphid nymph Aphis craccivora Koch (Hem.، Aphididae) (the common aphid species on the herbaceous plants in the pistachio orchards of Rafsanjan)، maize pollen and mix diets of psyllid nymph+aphid nymph as well as psyllid nymph+pollen on development and reproduction of 11-spots lady bird، C. undecimpunctata aegyptica was studied. All laboratory experiments were conducted in controlled conditions، 27. 5±0. 5°C، RH 55±5% and photoperiod 16:18h (L: D). The results indicated that pollen is not a suitable food for this species since both larvae and adults died when reared on this diet. However، the other four diets were considered to be the essential preys. The preimaginal stages of ladybird on psyllid nymph، cowpea aphid nymph and mix diets of psyllid nymph+ aphid nymph and psyllid nymph+ pollen were lasted 14. 9، 11. 9، 12. 2 and 14. 6 days on average respectively. The lowest mortality of larvae was obtained on mixed diet of psyllid+aphid، although it was the highest when they fed on psyllid+pollen. The emerged ladybird adults that fed on aphid nymphs during of the larval period were heavier than other diets. The female adults’ life span of ladybird on psyllid، aphid، psyllid+aphid and psyllid+pollen were 52. 3، 61. 1، 41. 4 and 56. 2 days، and their fecundity were obtained 826، 1947، 1281 and 727 eggs on average respectively. It was found that C. undecimpunctata aegyptica is considered as a psyllophagous coccinellid beetle although it is known as an aphidophagous ladybird too. The conservation strategy in pistachio orchards is recommended to increase the efficiency of psyllid natural enemies in pistachio orchards at this stage.