Plant Protection
Year:2011 | Volume:33 | Issue:2|Papers Count:10

Colorado potato beetle, Leptinotarsa decemlineata (Say), is a serious pest of potato in the Ardabil. In this study, the repellent and antifeedant effects of essential oil of five plants Teucrium polium L. Pelargonium roseum Andr, Artemisia sieberi Besser, Artemisia dracunculus L. and Citrus limonium Risso on the adult and third instar larvae of the beetle were investigated in a greenhouse under 24±1OC, 50±5 RH and 16: 8 h (L: D) in 2009. In a free choice assay the lowest number of adult females was estabilished on plants treated with the concentration of 500 ml/l of T. polium and A. dracunculus. The lowest number of eggs was laid on plants treated with concentrations of 500 ml/l of T. polium. Treating the potato leaves with the concentrations of 500 ml/l essential oil of A. sieberi, C. limonium, P. roseum and T. polium resulted in the settling of the lowest number of the third instar larvae on the leaves compared with other treatments. The lowest mean relative growth rate of the third instar larvae was seen in potato leaves treated with the concentrations of 500 ml/l of essential oil of C. limonium and P. roseum. It can be concluded that the essential oils of A. sieberi, A. dracunculus and T. polium have repellant effect on adult and the essential oils of A. sieberi, C. limonium, T. polium and P. roseum have repellant effect on third instar larvae of Colorado potato beetle. Based on these results it can be concluded that the essential oils of T. polium had highest effect in IPM of the Colorado potato beetle.

Resistance of 14 genotypes of red and white bean (including: D3, D10, D12, D81083, BRB188, ARS-R93003, Sayad, Daneshkadeh, Sadaf, Dehghan, Kara casehiro, Goynok98, Jules, G-11867) to two-spotted spider mite in laboratory and greenhouse conditions were studied. Lab studies were conducted using leaf disk bioassay with introducing 5 adult female mites on 2 cm diameter leaf disk and recording number of eggs, mite mortality and host damage after 72 hrs. In greenhouse conditions, when plants grew to 2 leaves stage, infestation was done by introducing 5 adult female mites (3-5 days in age) and mite population was studied after 2 weeks. Moreover, host perference and concentration of phenolic compounds were measured. Results indicate that Kara casehiro is the most susceptible, whereas Dehghan and D81083 are the most tolerant genotypes. There was no relationship between concentration of phenolic compounds and resistant to two-spotted spider mite.

Samples of infected corn plants grown in different parts of Khuzestan province (Andimeshk, Dezful, Shoush, Shoushtar and Mollasani) were collected in 2006.One hundred and thirty five isolates of F. verticillioides were recovered from different parts of the plants (root, crown, stem, male inflorescence and cob) by using Nash & Snyder medium. Seventy five isoletes were selected for the vegetative compatibility groups (VCGs) studies. Nit mutants were generated on two different media containing 3 and 5% KClO3 (Minimal medium=MMC), (Potato dextrose agare=PDC) and Czapeck medium containing 3% KClO3 (Czapeck).Collectively 668 nit mutants were obtained. Nit mutants were classified into 3 phenotypic classes (nit1, nit3 and NitM) according to their colony morphology and growth on basal medium supplemented with one of the sodium nitrate, sodium nitrite, hypoxantine or ammonium tartarate with the frequencies of 42.66, 23.64 and 33.7% respectively. Nit mutants were used to force heterokaryon formation. All of the isolates were grouped in to 34 VCGs, of which, the largest one had 7 members and 13 VCGs had only one member each. Isolates from different areas formed several VCGs. For instance of all the VCGs identified, 6 were from Andimeshk, 6 from Dezful, 8 from Shoush, 7 from Shoushtar and 7 from Mollasani.Of all the 34 identified VCGs ten were common in more than of one area and the rest occurred only in their site of origin. In this study no special relationship was observed between VCGs and the geographic origin of the isolates. These results indicate a high level of genetic diversity in populations of F. verticillioides associated with corn plants in Khuzestan province.

Mite species of the family of Eriophyidae (Acari: Prostigmata) are the most harmful mites of olive in most olive–growing countries. In this study, two species, Aceria oleae (Napepa) and Oxycenus niloticus Zaher & Abou–Awad, of this family were collected and identified from Tarom, north of Zanjan province during 1998 to 1999. These mites are serious pests, especially in the greenhouses of olive propagation. A.oleae usually live on the underside of terminal olive leaves where it inserts itself under the star shape hairs and causes them to drop off and to make yellow leaf spots and various forms of leaf deformation or defoliation. O.niloticus is normally found on upper surface of terminal olive leaves and produces some leaf pitting and deformation. In early October, under natural conditions, these mites refer to be on suckers which were the most important sites of feeding for them. In this study, twenty-five genotypes of olive (most from Hashemabad orchard, Gorgan, north of Iran) were evaluated in relation to their resistance to these species at completely randomized design. The evaluation was carried out in the greenhouse and infestation rate of treatments was recorded based on leaf damage index (reaction of leaf to mite feeding × percentage of leaf area infestation).Based on the greenhouse scoring, six categories were designated: F6 genotype with relatively immune response, E1, M4, J4, J11, 30-Ilam kolafaraj and 61-shengeh Gorgan with highly resistance response, D8, B8 and sevilana with resistance response, F10, E11, H7, I6 and A12 with moderately resistance response, D2, F7, C12, G8, C5, F2 and Roghani with susceptible and D12, E2 and Zard with highly susceptible response. Considering the high density of eriophyid mites in propagation greenhouses and possible of their transfer to pest appropriate areas (such as Gilan and Golestan provinces), application of above resistant genotypes or use of them to produce resistant cultivars are recommended.

Types of insects digestive enzymes are generally associated with their food regimes; and at least, the predominant presence of an enzyme indicates that the diets of the target insects contain high levels of its substrate. Insect digestive enzymes show considerable different activities in relation to their individual conditions and developmental stages. In this study, it was revealed that the type of food (several kinds of seeds of umbelliferous plants) had no significant effects on the enzyme activity of the stripped bug, Graphosoma lineatum (L.). The results showed that the enzyme activity in male and female adults will differ 4.5 and 3.5 times, respectively, if the insects’ biological and physiological conditions are not similar. In general, females’ enzyme activity was greater than that of the males. Environmental temperatures (4-30OC) did not affect the a-amylase activity. In starved insects (0-48 hours), the most enzyme activities were observed in 24-hour (12.32 U/mg protein) and 36-hour (14.13 U/mg protein) starved insects which had not significant difference to each other. Enzyme activities were similar between the two salivary glands of an individual bug which shows that these two glands respond to the related stimuli simultaneously. During the circadian cycle, enzyme activities were different. This was related to the different conditions of the used insects.a-amylase activities in insects obtained from 10th to 17th generations had not significant differences to each other. Despite from the similarities between some results of the present study with the results of other researchers, we confirm this theory that we are not able to establish a generalization about insect digestive enzymes properties and each species should be investigated separately.

The sunn pest, Eurygaster integriceps Put. is an important pest of wheat in Firozabad region of Ardabil province, Iran.In this study the spatial distribution of overwintered adult was investigated in rainfed wheat fields. Then, fixed precision sequential sampling plan was developed and validated for estimating overwintered adult density. Iwao's patchiness regression gave a better fit to data (R2 =0.96) than Taylor power law ((R2 =0.81). The aggregation index (b=1.12) was significantly greater than one. These results indicate that the distribution of overwintered adult sunn pest fits the aggregation model in rainfed wheat fields. Kuno's model was designed for estimating of population density of overwintered adult. Ten independent data sets were used to evaluate the validation of Kuno's plans using resampling by the RVSP. Average sample numbers (ASN) for precision level 0.1 and 0.25 were 101 and 14 quadrats, respectively. This result showed that, the using of fixed precision sequential sampling plan can be useful in rapid estimation of overwintered adult density of sunn pest for managing decision making by reducing the required sample sizes in rainfed wheat fields.

The use of resistant cultivars remains one of the most reliable methods to manage the pests. In this study the mechanism of resistance in 10 lines of rice for 3 kinds of resistance (Antixenoses, Antibioses and tolerance) was studied. The egg set of striped stem borer on the leaf of considered lines for Antixenoses and larva weight mean and survival percentage of larva were evaluated for Antibioses resistance.Percentage of white head was used for determining the tolerance mechanism to striped stem borer. The results showed that the maximum egg set, percentage of larva survival, dead heart and white head belong to L3 [(Sang-e-Tarom × Tarom-e- Daylamani)] and the highest weight of larva obtain on the L5 [(IRRi-2 × Nok-siah)]. In this study the most susceptible and resistant genotypes were L3 [(Sang-e-Tarom×Tarom-e-Daylamani)] and L4 [(fajr×Nok-siah)], respectively. Study of correlation coefficient showed that the height of plant and amount of chlorophyll were effective on Antixenoses. Stem diameter and number of tiller were effective on Antibioses mechanism. Finally, mechanism of tolerance was also affected by stem diameter.