Study of the Capability of Sunn Pest (Eurygaster integriceps) to Synchronize Life Span with the Phenological Stages of Wheat and BarleyResistance to Sunn Pest (Eurygaster integriceps Put.) in Durum Promising Lines
Mechanisms of Resistance to Sunn Pest (Eurygaster integriceps Put.) in Wheat Cultivars.
Investigation on Host Preference of Sunn Pest to 9 Cultivares in Abarkouh of Yazd Province.
Biological and Ecological Features of Harmful Species of Aelia in Cereal Growing Areas of Iran
Body Weight Variations of Eurygaster integriceps Put. in Fields and Altitudes
Analysis of Sunn Pest Periodic Outbreaks in Iran
Migration of Sunn Pest from Altitudes to Cereal Fields in Varmin
Study of the Capability of Sunn Pest (Eurygaster integriceps) to Synchronize Life Span with the Phenological Stages of Wheat and Barley
M. REZABEIGI
Plant Pest & Diseases Research Institute, Tehran, Iran.The capability of Sunn Pest to synchronize its life span with the phonological stages of wheat and barley was evaluated in experimental field in Varamin Agricultural Research Station for two consecutive years (1996-1998). The experiments were carried out in the form of the two factors complete randomized block design with 3 replications. The first factor was sowing date and the second one was wheat and barley cultivars. Additional experiments carried out in the farmer’s field conditions. The results are as follows:
1. In barley field, Sunn Pest’s life cycle was completed 7-10 days earlier than that in the wheat fields and Sunn Pest synchronized its life cycle with phonological stages of hosts.
2. In barley fields 75% of the pest population were able to complete their life cycle on harvesting time, but at the same time wheat plants were at the waxy stage and only 27% of the individuals were in adult stage.
3. At harvest the weight of males and females was found to be significantly higher in wheat than that in barley and a significant correlation of the weight of newly emerged adults with plant growth span.
4. The earliness of wheat did not significantly affect Sunn Pest population and adult’s weight reduction in barley fields could not affect the pest population because they can fly to neighboring wheat fields and complete their feeding cycle. Therefore control of this pest in barley fields should not be overlooked.
from: Proceeding of the 15th Iranian Plant Protection Congress, Sept. 2002
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Resistance to Sunn Pest (Eurygaster integriceps Put.) in Durum Promising Lines
V. GHADIRI
Plant Pests & Diseases Research Institute, Tehran, Iran.Supplying the resistant cultivars and using them to reduce damage is one of the effective ways for controlling of Sunn Pest. A total of 21 promising lines of durum wheat were planted in R.C.D. design at research station of Seed and Plant Improvement Institute in 1999 and 2000. We chose 10 ears of durum wheat and covered them with a net cage when the third instar of nymphs appeared. We set up four net cages (two cages for rearing the nymphs and two cages as check) for each replication in the experimental field. During harvesting stage we carried all of the cages into the laboratory and counted all the nymphs and adults of the pest. Percentage of damaged grains was determined for each replication. Results showed that there are significant differences between the treatments of percentage of nymphs, percentage of adults and percentage of damaged grains. Calculated resistance coefficients for different treatments showed that treatment no 13 (820 co 7784/wi22A18) with the total resistance coefficient of 3.28, was most resistant and treatment no 6 (719 Aco-89) with the total of 5.83 was most susceptible line of wheat to Sunn Pest among different lines. Rate of resistance and susceptibility was determined for all of the durum lines.
from: Proceeding of the 15th Iranian Plant Protection Congress, Sept. 2002
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Mechanisms of Resistance to Sunn Pest (Eurygaster integriceps Put.) in Wheat Cultivars.
M. REZABEIGI (1), GH. RADJABI (1), G. NOURI GHANBALANI (2), G.A. ABDOLLAHI (1)
1-Plant Pests & Diseases Research Institute, Tehran, Iran.
2-College of Agriculture, University of Mohageg-e-Ardabili, Ardabil, Iran.Resistant, semi-resistant and susceptible wheat cultivars to Sunn Pest infestation were determined during 1996 to 1998. Indices of preference percentage of over-wintered adults, damage caused by studied to determine the antixenosis. Indices such as weight gain of the Sunn Pests, 14 days after feeding, the number of eggs produced per female, weight of newly emerged adults, dry weight and body fat percentage of newly emerged adults were studied to determine the antibiosis. Lastly, indices including percent of grain damaged per newly emerged adults, yield reduction percentage, weight reduction percentage per 1000 grains, and weight reduction percentage in per 50 damaged grains by Sunn Pest were studied to determine the tolerance. In addition, nine regression equations were developed to separate mechanisms of antibiosis and tolerance. According to these analyses, Falat, Gholestan, Tabassi and Zardak cultivars showed noticeable antixenosis. Falat, Gafghaz and Azadi cultivars showed the highest antibiotic effects. Falat, Azadi, Gholestan and Gafghaz were the most tolerant cultivars to the pest infestation. In resistant cultivars, combination of antixenosis, antibiosis and tolerance were shown to influence the resistance. Low levels of these functional groups I other cultivars contributed to the susceptibility. Correlations between the index of resistance and the indices of antixenosis, antibiosis and tolerance were significant.
from: Proceeding of the 15th Iranian Plant Protection Congress, Sept. 2002
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Investigation on Host Preference of Sunn Pest to 9 Cultivares in Abarkouh of Yazd Province
A. MOHAMMADI KHORAMABADI (1), A. ARZANI (2), B. HATAMI (2)
1-Jihad-e-Agriculture Organisation of Yazd, Iran.
2-College of Agriculture, Isfahan University of Technology, Isfahan, Iran.Identification of resistance genetic resources and use of resistant varieties can be considered as an effective method in Sunn Pest control. This study was conducted to evaluate host preference of different life stage of the pest including overwintered adults, 4th and 5th nymphal instars and newly emerged adults to 9 wheat cultivars including 4 durum and 5 bread wheat cultivars; (Shahdas, Altar-84, Dipper-6, Massara-1, Moghan-1, Tabasi, Niknejad, Anza and Tajan, respectively) in Abarkouh of Yazd province using a Randomized complete Block Design with 4 replicates in a fan pattern. The results showed that the cultivars varied significantly at 1% at the different developmental stages of Sunn Pest. Niknejad and Tabasi attracted the highest and lowest number of overwintered adults respectively. 4th and 5th nymphal instars and newly emerged adults showed the maximum preference to Tabasi and the minimum preference to Tajan. This also indicated that feeding behavior of different stages of Sunn Pest is varied.
from: Proceeding of the 15th Iranian Plant Protection Congress, Sept. 2002
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Studies on the Relationship Between Resistance to Sunn Pest (Eurygaster integriceps Put.) of Different Wheat Genotypes and Starch Granules of Grain Endosperm
P. ZAMANI (1), M. REZABEIGI (2), M.R. GHANNADHA (3), R. BOZORGIPOUR (4)
1-Karaj Unit, Islamic Azad University.
2-Plant Pests and Diseases Research Institute, Tehran, Iran.
3-College of Agriculture, Tehran University, Karaj.
4-Seed and Plant Improvement Institute, Karaj.
Resistance to Sunn Pest of 30 wheat genotypes has been evaluated under field conditions during the years 2000-2001. The evaluation method consisted of infestation of host plants by Sunn Pest nymphs in rearing cages. According to means of resistance indices, genotypes (Albor ZX, K 6290914/cno//K 58/Tob/3,...),(A-12-1-32-438//Rsh/Bb/Kal/Ald”S”....) were ranked as resistant and genotypes (Kal//Bb/Kal/3/Au/50E/3*Kal/4/Brochis/...), (Kayson/Glenson) grouped as susceptible. To study the relationship between resistance of wheat genotypes and abundance of starch granules, the small granules (1-10u) and large ones (10-30u) have been counted in a definite area of undamaged and damaged flour of the genotypes. Results showed that there are significant differences among the genotypes regarding abundance of starch granules in undamaged and damaged grains. Damaged grains showed 36.9% decrease of small granules indicating Sunn Pest feeding generally on this size of granules. According to results of analysis of correlation, genotypes having more large granules in their undamaged grains and losing less small starch granules are relatively more resistant. Thus evaluation and preliminary selection of varieties and lines resistant to Sunn Pest seem to be feasible by measuring the number of starch granules in damaged and undamaged grains. Ridge regression analysis has been used to calculate the linear regression equation.
from: Proceeding of the 15th Iranian Plant Protection Congress, Sept. 2002
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Biological and Ecological Features of Harmful Species of Aelia in Cereal Growing Areas of Iran
GH. RADJABI
Plant Pests and Diseases Research Institute P. O. Box 19395 - 1454 , Tehran , Iran.The biological and ecological features of 4 Aelia sp. was studied. Their distribution and comparative importance was determined. Aelia furcula is able to produce a second generation in the nature when conditions are favourable. Normally, the overwintered adults migrate to cereal fields shortly after Eurygaster integriceps. First generation adults appear 20 June to 10 July. About 70% of the new generation adults move to aestivation sites and the remaining portion initiate a second generation. 80% of first instars die. 90 to 100% die as second instars. We have never seen fourth instar of the second generation in nature.
The biology of Aelia acuminata was studied in the Varamin region. The activity of the overwintered adults occurs at the same time as E. integriceps. The adults of the first generation can be divided into 3 groups. One group starts aestivation immediately without any attempt to initiate a second generation. The second group becomes dispersed in wild and cultivated plants surrounding harvested cereal fields. These individuals normally disappear during October. The third group initiates a second generation, a small percentage of which completes their life cycle.
In rain-fed areas the initiation of a second generation by Aelia melanota and A.virgata is more probable than in irrigated areas. This difference in biology results from environmental suitability of the former regions with their higher altitudes and more abundant precipitation. First and second instars are found there occasionally. We have never found third instar. Individuals of the second generation do not complete their life cycle in the cereal growing regions of the country.
A. furcula and A. acuminata do not migrate very far or exopand their range. A. melanota and A. virgata have one population with migratory habits (in the irrigated regions) and one population which is non -migratory (in dry farming lands). Aestivation and hibernation of A. acuminata takes place in the vicinity of cereal fields. We have rarely found them hibernating in the surrounding altitudes. A. furcula feeds mainly on rainfed cereals grown on the slopes of altitudes and hence they pass their summer and winter diapausing in the surrounding highlands and altitudes. A. melanota and A. virgata aestivate and hibernate in the mountains and lower hills. The hymenopterous and dipterous parasitoids of these insects have been identified and their capability has been studied in different parts of the country. A list of host plants of Aelia species in the altitudes and in the fields has been prepared. The intensive and extensive feeding activity of these insects on noncultivated plants has led us to believe that the increasing degradation of rangelands and bushlands is the major factor caused by the continuous change of feeding habits of Aelia species in IRAN.
from: Appl. Ent. & Phytopath. Vol. 66, No. 1&2, Feb.-Aug. 1998
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Body Weight Variations of Eurygaster integriceps Put. in Fields and Altitudes
GH. RADJABI
Plant Pests and Diseases Research Institute, P.O. Box 19395-1454, Tehran, Iran.This research , done for three consecutive years, was aimed at increasing our knowledge in connection with the implementation of early and rapid harvesting, which is considered the fundamental control measure for Sunn Pest. The weight of newly emerged adults averaged 78, 72 and 82 mg. In 1991, 1992 and 1993. Immediately after their arrival in their estivation sites in the altitudes their average weight was 142, 136 and 145 mg. in ’91,’92 and ’93. At the end of the hibernation period and just prior to their flight to the fields, their average weight was 110, 103 and 105 mg. Average weight loss during the overwintering period was 32, 33 and 40 mg. in 1991, 1992 and 1993 respectively.
from: Appl. Ent. & Phytopath. Vol. 62, No. 1&2, Feb. 1995
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Analysis of Sunn Pest Periodic Outbreaks in Iran
GH. RADJABI
Plant Pests and Diseases Research Institute, P. O. Box 19395-1454, Tehran, Iran.In this paper efforts made during more than 30 years to find a reasonable explanation for the periodic outbreaks of Sunn Pest that occur every 6-8 years and the results obtained are presented. The main points based on the evolutionary phases of this phenomenon in Iran, are the following:
- As a result of overcrowding of the pest during the outbreak periods, the overwintered adults destroyed the wheat fields either totally or partially before the plants could produce any grain.
- The offspring not finding sufficient food, suffered high mortality especially in the nymphal stage. The survivors flew to their hibernation areas with much less fat and food reserves in their bodies than in normal years.
- These adults perished more easily during their passive life in the altitudes. Dryness and the heat of summer and frosts of winter killed them in much greater numbers than in other years.
- Consequently there was an abrupt fall in population density.
- This trend continued for two to three years leading to a depression of activity and a high decrease in population numbers.
- This population not finding any obstacles for rapid increase and particularly due to the very common late and slow harvest, led to a new outbreak.
- The oviposition period is shorter for Sunn Pest that belong to the outbreak population and are well fed.
from: Appl. Ent. Phytopath. Vol. 61, No. 1&2, Feb. 1994
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First Report of the Existence of Sunn Pest Egg Parasitoid, Trissolcus festivae Viktorov (Hymenoptera: Scelionidae) in Iran and some Preliminary Studies on its Biology
GH. RADJABI
Plant Pests and Diseases Research Institute P.O. Box 19395-1454, Tehran, Iran.Adult Trissolcus festivae Vik. were first found in 1993 emerging from Sunn Pest eggs in wheat fields in Karaj, Qazvin Region. This observation was also made the following two years leading to the following: T. festivae has been found in Zanjan Region in two provinces of Tehran and Zanjan, and Farahaan Region of Markazi Province. T. festivae prefers the plains located on the slopes of mountains. In these plains (altitude 1300-1600m.) wheat is grown extensively and is attacked annually by Eurygaster integriceps. T. festivae also parasitizes eggs of Eurydema spp. It appears that E. integriceps is the preferred host. Two generations of T. festivae are completed during spring before harvest of wheat. Second generation adults readily parasitized eggs of E. integriceps if they were fresh. Biological studies were done in fields at Karaj (altitude 1400m.).
from: J. Ent. Soc. IranVol. 14, March, 1994
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Reproduction of Eurygaster integriceps Put. and Aelia furcula F. in their Hibernation Sites and its Connection with these Bugs Extension in Iran
Gh. Radjabi and F. Termeh
Plant Pests and Diseases Research Institute, P. O . Box: 19395-1454, Tehran, IranObservations in 8 hibernation sites in the high plateau of Central Iran from 1984 to date, proved the existence of a considerable population of Sunn Pest remaining in the altitudes where they feed on a number of wild plants belonging to different botanical families. We found 17 plants being fed on by hibernated adults of Sunn Pest and their off - spring , among which 8 have been found to be used by the adults and nymphs of Aelia furcula Fieb. In some of the overwintering sites we have surprisingly found the oophagous parasites of the genus Trissolcus being sufficiently active and abundant . This phenomenon proves the installation of a more or less important population of E. integriceps in their hibernating sites.
The destruction of highlands vegetation by the increasing expansion of rain - fed cereals and its relation to the evident extension of these pests in recent years is discussed.
from: Ent. Phyt. Appliq. Vol. 55, No. 1&2, Feb. 1988
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Migration of Sunn Pest from Altitudes to Cereal Fields in Varmin
GH. RADJABI
Plant Pests and Diseases Research Institute, P.O. Box 19395 - 1454, Tehran, Iran.This research was done for 12 consecutive years. There has been one migration per season during five years, two migrations during five years and three migrations during two years. The earliest downward migration started March 8 and the latest April 20. The average daily mean temperature in the plains of Varamin at the starting days of the migrations was:
First flight : 13.5o C (average of twelve years)
Second flight : 13.5o C (average of five years)
Third flight: 14.3o C (average of two years)There was no connection between the accumulation of degree-days (DD) and the onset of Sunn Pest return flights. Furthermore, the sudden incidence of high temperatures did not usually induce return flight of the insect, unless during the 3-2 preceding days there was a more or less gradual increase of ambient temperature. This phenomenon has been found more conspicuous during the first flight.
Mass Rearing of Trissolcus grandis on Graphosoma lineatum Eggs for Biological Control of Sunn Pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae)
S. SHAHROKHI
Sunn Pest Research Department, Plant Pests and Diseases Research Institute, P.O. Box 19395 - 1454, Tehran, Iran.For the biological control of Sunn Pest with scelionid egg parasitoides, mass rearing of an alternative host for egg production is nessesary. Due to the univoltine nature of Eurygaster spp., Graphosoma spp. that could be easy mass reared showed promise. Graphosoma lineatum reared on seeds of umbliferous plants such as Heracleum persicum and Foeniculum vulgare produced eggs year-round (Asgari 1993- 95). To improve oviposition of G.lineatum for egg production and quality control of Trissolcus grandis bred on their eggs, several food combinations, different rearing conditions and conservation of eggs were investigated from 1995- 1997. Parasitism rates, emergence, sex ratio and searching ability of the wasps were also evaluated.
These insects can be reared for 9 generations on seeds of H. persicum, F. vulgare , Torilis arvensis or combinations of these in the laboratory at 28± 10 C, 50- 70% rH and 16/8 L/D (in plexiglass boxes). However, those reared on Torilis did not produce eggs. When Torilis seeds were added to Heracleum seeds , eggs deposition reduced considerably. There was a positive correlation (r= 0.72) between life span of adult females and oviposition rate. Eggs laid in the first 2-3 days (5.3-6.4% of total eggs) were not fertile. Populations collected from nature from early June to late August produced more eggs (258.2-461.8) than those collected in September or later. The latter showed a more or less diapausing behavior with a long preoviposition period and fewer eggs deposited. There was a significant difference in the number of eggs among females collected in late spring and summer (461.8) compared to laboratory-reared generations (53- 104). This indicates that rearing conditions still need to be improved. For storing and preserving Graphosoma eggs we found that preserving them in 10, 17, 25 and 50% dimethyle sulfoxide solution at - 22 o C protected their quality about 5.5-11 months. This was better than storing them without any protective solvent . However, parasitism rate was low (55. 7- 66%) and sex ratio (female/male ) was low compared to using fresh eggs. Placing eggs at –196º C in a deep freezer was necessary for long-term preservation (Gennadiev 1980). Laboratory-reared wasps had a lower stability and searching capacity when compared to the natural population. Improvements in laboratory rearing techniques are needed.
Trissolcus esmailii sp. n. (Hym. Scelionidae), an Egg Parasitoid of Eurygaster integriceps Put. and Dolycoris baccarum L. in Iran
GH. RADJABI and F. TERMEH
Plant Pests and Diseases Research Institute, P.O. Box 19395 - 1454, Tehran, Iran.Trissolcus esmailii sp. n. is described from Darab and Tooysserkan, Iran . A key to the world nearest species of Trissolcus is provided.