Applied Entomology and Phytopathology
Year:2002 | Volume:70 | Issue:1|Papers Count:13

During 1996-1997. biology of mango hopper was investigated by weekly sampling and use of sleeve cages in mango orchards in Minab and Siahoo regions in Hormozgan province. It showed that, one of the most serious pests of mango trees specially during the flowering season is "Mango hopper". It has been the main factor of crop losses in southern parts of Iran in recent years.Injury caused by adults and nymphal stages by sucking the sap from new leaves and inflorescence which resulted the secretion of honeydew on mango plant parts. Nymphal damages found on which attack the inflorescence only, leading to wilting of flowers and death. Fruit setting is also inhibited and young fruits fall off. The eggs are laid in flower buds and tissues of panicle during flowering season. The incubation and nymphal period of the pest were estimated between 9-17 and 20-24 days respectively under natural condition of Minab and Siahoo conditions.The Mango hopper had one generation during in year. Overwintering was observed in adult stage, mostly on mango trees. Maximum and minimum population density of the pest occurred in flowering season (March. ApriL May) and cold months (Jan, Feb.) respectively.

For collection and identification of store pest products, an investigation have been conducted in Gonbad and Minoodasht during a weekly and monthly interval.Stores and non-state stores of agricultural products such as flour firms, spaghetti, etc. were collected by using common methods. Specimens were sort out according their morphological characters at insect family level. Then with other keys of identification upto species level also determined.During two- year-sampling, 1433 inspections were conducted, which 960 sampling carried out in Gonbad while rest of them take place in Minoodasht. 24 species were recorded into 14 families of beetels. Four species from three familiesof the moths, one species from cockroaches, bristletails and psocoids also collected in this survey.In total, Rhysopertha dominica, Sitophilus granarius and Triboliwn confilsum observed with high percent of abundance, but according their site distribution and damages of insect pests were found ditler from each other.

Powdery mildew resistance was evaluated in 44 wheat cultivars selected from a total of 400 relatively resistant wheat cultivars during the growing season in 1994. In subsequent year, 34 of these cultivars were tested for resistance under field conditions in Gharakhil and Baie-Cola in Mazandaran province. A total of 15 wheat lines and cultivars exhibiting reasonable levels of resistance against powdery mildew were identified. These wheat plants could be utilized for incorporating resistance genes into high yielding wheat varieties in future breeding programs.Infection index of plants was graded between "O" (immune) to "9" (highly susceptible). Line carpenter/Aid "S" Showed to be immuneand line Ad "m" Pewee "s" was highly resistance. The average index for all the tested cultivars showed to be less than "5" using 8 internationally standard wheat varieties in a greenhouse experiment. Three races of the pathogen (races "46", "52" and "75") were identified throughout the region. These 8 varieties were planted in plastic pots and were placed in the soil on the margin ofthe wheat field. In spring of 1995 we realized that the variety "Weihenst, M1" carrying (Pm4b) gene was resistant to all races of pathogen present in the entire area. Greenhouse studies also showed the same results. Host range studies of powdery mildew fungi on graminacious weeds of Mazandaran province showed that except Lolium temolentum, other species such as Avena sativa, Bromus japonicus, Phalmis minor and Aegilops triuncialis were all susceptible to the pathogen. When fungus conidia as inoculum were sprayed on these grasses, only species of the genera Triticum and Aegilops showed to be infected.

In this study some of the important aspects of the biology of the sugar beet weevil B. obliquefasciatus, a serious pest of early season in warm and dry regions of Isfahan province, was investigated. The adult weevils emigrate from their hibernation sites and feed voraciously by on the cotyledons of the sugar beets upon their emergence. The female oviposite on the surface of the cotyledons. The first instar larvae emerge during 7± 0.73 days under the 28°C and 24% relative humidity condition. They make a hole in the leaf and fall down in cracks of the soil near the roots. They feed from the roots and complete their growth after 4 instar during 15-20 days then pupate in their feeding hole in roots or in a soil cocoon near the ground surface. Pupation period is 10-15 days. This pest has one generation annually and the new generation will overlap with the old one. The population fluctuation studies in this region during 1990 and 2000 revealed that number of captured weevils increase slowly from May to June, based on the period of beet culturing, and then decrease. It increases again to its highest amount in July when the new generation appears and finally decreases till August.

Red palm weevil (RPW). Rhynchophorus ferrugineus Oliv., is a destructive pest of different palms in Asia, North Africa and South Europe. At present time, it is an internal quarantined pest in Iran which damage on date palm is limited to Saravan region (Sistan & Balouchistan province). Based on accomplished investigation. Mazafati date palms were the most desirable host for RPW.Several experiments were caried out on the food preference of RPW on 5 date palm varieties includings Mazafati, Rabbi, Halileh, Zardan, Pimazoo and a native wild palm (Nannorrhops ritchiana (Griff) Aitch.), during 1999-2001.Based on the laboratory studies, larval mortality maximum and minimum were in Zardan and Halileh, respectively. The highest pupal mortality was recorded 100%, which found in wild palm. The maximum and mlI1lmUmof adult emergence were observed for Mazafati and wild palm respectively. The life span of RPW was maximum in Zardan and minimum in Mazafati. The highest and lowest daily oviposition were observed in Mazafati and Zardan respectively.To determine the reasons offood preference ofRPW, vascular tissues of different varieties of date palms and wild palm were analysed and dry weight. crude fibre. total sugar, fat and 12 chemical elements were measured. The stepwise multiple regression analysis showes that, the intraction of various nutrient components affects the vital qualifications of RPW. The most effectine nuitrients and element were found sugar and calcium. Sugar was correlated with growth and daily oviposition and reduction in mortality, while increasing of calcium clearly inhibited RPW growth.

Granary weevil, Sitophilus granarius L.(Col;Curculionidae), is a cosmopolitan pest that feed on . cereal grains and cause heavy damages particularly wheat grains. The highest level of damage occurs during larval period when 1arvaefeed on kernel contents. Females only bore in grains to lay eggs. Larvae and pupal periods are completed inside the grains. Fourteen wheat varieties were used to determine sex ratio, developmental period and FI generation population under laboratory condition. Results obtained for both sexes were found identical. The highest number of weevil insect in seed kernel was counted for Arvand, Navid and M-70-12, while the lowest was for Falat. Golestan and Hirmand. The minimum developmental period were recorded for Arvand, Khazer and M-70-12, whereas maximum number observed for Hirmand, Ghods and Falat respectivety.

Fusarium dry rot is one of the most important post harvest fungal diseases of potato tubers in the store. In 1996 the susceptibility of 16potato cultivars were assessed to three Fusarium species causing dry rot in Isfahan. The cultivars were Oleva, Baraka, Cosima, Caeser ,Korrigane, Erigo, Aida, Atlas, Melisa, Marijke, Tiva, Satuma, Desiree, Arian, Flava ard Fergate. Means of infection index of potato cultivars to different Fusarum species had significant differences. These potato cultivars had the maximum and minimum susceptibility to F. sambucinum and F. oxysporum respectively. The resistance of these. cultivars to Fsolani and F. oxysporum was not independent. Therefore, if a cultivar susceptible to F solani it is also susceptible to F oxysporum and conversly. Saturna was found more tolerant to the three Fusarium species than the other cultivars.

During one year study, 76 soil samples were collected from (1996-1997) forests and fields of Kermanshah province that had not previously been treated with B. thuringiensis. Bacteria were isolated according modified method of Ohba and Aizawa. From 76 samples which were tested, about 59 spore forming bacteria were isolated that only one of these were identified as B. thuringiensis. This isolate and two other native isolates were compared with Var. kurstaki through bioassay method on third instar larva of Plodia interpunctella that native isolates was more effective than var. kurstaki on third instar larva of Indian meal moth.