Journal Of Crop Protection
Volume:3 Issue: 2, June 2014

The sever epidemic of Fusarium head blight (FHB) as a devastating disease of cereal crops has been occurred on wheat in North and Northwest of Iran in recent years. The in vitro production of Deoxynivalenol (DON) was qualitatively evaluated in 41 Fusarium isolates collected from wheat heads associated with the scab disease, in Moghan area/ Northwest of Iran. Infected wheat heads were collected during 2004-2007. The isolation of causal agents carried out using standard methods and according to morphological characteristics and using valid descriptions, all isolates belonged to Fusarium graminearum species complex and F. culmorum of which the first species was dominant. In order to evaluate the potential of DON production in isolates, this mycotoxin was extracted and qualitatively examined by TLC method. The quantification of DON was achieved using HPLC method. TLC results indicated that 54.5% of studied isolates produced DON but there was no significant relationship between this property and cultivars or sub-regions or years. Also based on HPLC analysis, maximum content of DON belonged to F. graminearum isolated from cv. Izen green in Moghan Agro-industry company fields in 2004 with 5827.11 µgkg-1. The results of present study show that DON mycotoxin is produced in various contents by F. graminearum isolates on different cultivars and in different origins/ years. Since DON plays a role in pathogenesis and is of paramount importance in contamination of wheat grains these results gives a better insight to the significance of this disease in Northwest of Iran.

Among the recently collected chalcidoid wasps in a rice field of eastern Guilan province (coast of Caspian Sea), at July 2012, there were some specimens of Pteromalidae belong to the genus Callitula. It was identified as Callitula ferrierei (Bouček, 1964). Both genus and species are new record for Iranian fauna. Morphological characters and geographical distribution of the newly recorded species are given.

Colorado potato beetle, Leptinotarsa decemlineata is one of the major insect pests of potato. Toxicity of spinosad, as a bio-rational insecticide, was investigated against various developmental stages of this pest. Bioassays were conducted by using the eggs, neonates, first, second, third and fourth instar larvae and adults. The potato leaves were impregnated with different concentrations of spinosad and applied for the adults and different larvae bioassays. The eggs were tested through dipping its masses into the insecticide solutions. LC50 values of neonates, first, second, third and fourth instar larvae and unsexed adults after 24 hours were 2.06, 3.19, 4.75, 6.46, 20.24 and 11.97 ppm (of commercial formulation), respectively. Results show that spinosad did not possess any ovicidal effects and the fourth instar larvae and neonates were the most tolerate and the most susceptible stages, respectively. Susceptibility of the neonates (up to 24 hrs after hatching) was significantly higher than first instar larvae (24-48 hrs after hatching). Developmental stages of Colorado potato beetle differentially responded to this insecticide. Since the control of L. decemlineata mostly relies on early season measures against the most susceptible stage(s), by considering no ovicidal effect, our results propose a limited interval, for avoiding the high tolerant larvae.

Essential oils are volatile mixtures of hydrocarbons with diverse functional groups. In the current study the effect of essential oils from five medicinal plants including Zataria multiflora and Nepeta cataria (Lamiaceae), Tagetes minuta and Artemisia siberi (Asteraceae), and Trachyspermum ammi (Apiaceae) were analyzed using GC-mass spectrometry. The toxicity of these plant essential oils against the adult stage of the cabbage aphid, Brevicoryne brassicae L. (Hemiptera: Aphididae) was studied using a fumigant assay.GC/Mass analysis revealed that the main essential oils varied between species. The most abundant components in N. cataria, Z. multiflora, T. ammi, T. minuta and A. sieberi were 4a-α, 7-β, 7a-α-nepetalactone (76.8%), carvacrol (62.1%), γ-terpinene (27.1%), limonene (13.0%) and artemisia ketone (48.0%) respectively. The fumigant assays showed that all of these essential oils were toxic to B.brassicae in a dose-dependent manner. The essential oils of N. cataria at 126, 63, 31, 16, 8, and 3 μl L-1 air caused 94, 76, 52, 46, 36, and 24% mortality within 24 hours, respectively. The same trend was seen when essential oils of the other plants tested against B. brassicae. These plant essential oils have great potential to be used in integrated pest management especially in greenhouses or other closed systems.

Cold hardiness is one of the most common adaptations of insects at low temperatures. To understand the cold hardiness strategy of beet armyworm, Spodoptera exigua (Hübner), six temperatures treatment were tested on the last instar larvae. Supercooling points of treatments were not significantly different. Two sugars, glucose and trehalose, as well as three polyols, myo-inositol, glycerol and sorbitol, were identified in these larvae. Trehalose was more affected in response to low temperatures in longer duration, and had a significant negative correlation with glycogen content. Despite the increasing sugar beet cultivation areas in Iran, beet armyworm population has been decreased in recent years. It seems that climate change regarding the global warming especially in autumn and winter could be a reason for decline in population outbreak of beet armyworm in the next generation. Based on findings of this study, it is suggested that overwintering larvae are freeze-intolerant insects but long term acclimation at sub-zero temperatures make larvae to tolerate presence of ice crystals in their body fluid.

The aphid species, Cinara pini (Linnaeus, 1758) reported in our previous work as a new aphid on pinus trees for Iran, was described using the classic method and through analysis of COI gene sequence. At the next step, we addressed the efficiency of the entomopathogenic fungus, Lecanicillium longisporum (Zimm.) Zare and Gams strain LRC 190, on the aphid. The fungus was administered to the second instar nymphs and adults using topical application procedure. The results indicated that the entomopathogen caused 90% mortality in adults over seven days at a concentration of 108 spores/ml, while the same control level was achieved for nymphs by 8 × 107 spores/ml. The LC50 values were obtained as 1.2 × 106 and 6.9 × 105 spores/ml for adults and nymphs, respectively. The present study suggests that the entomopathogenic fungus, L. longisporum could be considered as a potential candidate in biocontrol programs of C. pini. This is the first report on the pathogenicity of L. longisporum on C. pini.

Rosy apple aphid, Dysaphis plantaginea (Passerini), with worldwide distribution is an important pest of apple orchards. Host plant resistance is an essential component of integrated management of this insect pest. We investigated the resistance of seven apple cultivars, Malus domestica (Borkhausen), namely Granny Smith, Starkrimson, Golden Smoothee, Red Delicious, Golden Delicious, Boshghabi, and Shaki to rosy apple aphid under field and greenhouse conditions. The damage level by rosy apple aphid was significantly different among the tested cultivars preciously three week after infestation in both field and greenhouse conditions. The least leaf curling was observed on Shaki, while the most deformation was detected on Golden Delicious. There was positive correlation between damage in greenhouse and field studies. In addition, the lowest and highest numbers of aphids were observed on Shaki and Golden Delicious, respectively. Consequently, our results demonstrated that among the cultivars tested the Shaki cultivar is moderately resistant to rosy apple aphid and has the potential to be used in the integrated management of this aphid.

The Colorado potato beetle, Leptinotarsa decemlineata Say (Col.: Chrysomelidae) is an important pest of potato worldwide and study of its glucosidases is an important step to develop appropriate pest control strategies. In this study, some biochemical aspects of β-glucosidase in the Colorado potato beetle were determined. The results showed that β-glucosidase activity in the midgut of adults was 6.68 Umg-1. Maximum activity of midgut β-glucosidase occurred at pH 4 to pH 5.5; however, the enzyme is active at pH 3 to pH 7 more than 50% of its relative activity. The enzyme was stable at pH 3 to pH 8 for 2 and 8 hours incubation time. According to the results, optimal temperature for the enzyme activity was 50 °Cand its stability significantly was reduced at 50 °C during 1 to 8 days incubation time. The enzyme activity decreased with the addition of different concentrations of MgCl2, urea, Tris and CaCl2. Enzyme activity was highly decreased at low concentrations of SDS (1 mM).

The cotton bollworm, Helicoverpa armigera (Hübner), is a serious pest on a wide range of economic crops in many parts of the world. In this study, digestive proteolytic and amylolytic activities of H. armigera larvae (3rd to 5th instars) were evaluated on five main host plants including chickpea (cv Hashem), cowpea (cv Mashhad), soybean (cv 033), navybean (cv Dehghan), and corn (cv SC 704) at 25 ± 1 °C, relative humidity of 65 ± 5% and a photoperiod of 16: 8 (L: D) hours. The results indicated that the highest enzyme activity was in 5th instar. The highest general protease activity of 3rd, 4th and 5thinstar larvae was found on corn. The larvae fed on corn had the lowest trypsin activity. This leads to hyperproduction of chymotrypsin and elastase-like enzymes to compensate the inhibition of trypsin. The larvae of H. armigera reared on cowpea had the highest level of amylase activity, and the lowest activity was in the larvae fed on corn. The results revealed that among host plants tested, corn was more resistant (unsuitable) to H. armigera. Study on digestive proteolytic and amylolytic activities of H. armigera can be used in identifying the antidigestive or antifeedent compounds, which will help us to design appropriate management programs.

Fauna of the Aphidiinae (Hymenoptera: Braconidae) of Iran is reviewed and the data on their host aphid associations are summarized. Seventy-eight species belonging to 17 genera of Aphidiinae are listed in the associations with 193 aphid species. A total of 491 parasitoid-aphid associations are presented. The distribution of the Aphidiinae species in different parts of Iran and other countries is also discussed.

The fauna of the braconid genera Atanycolus Foerster, Glyptomorpha Holmgren, Pseudovipio Szepligeti and Vipio Latreille belonging to the subfamily Braconinae were studied in some parts of northern (Alborz, Qazvin, Gilan and Tehran) and southern provinces of Iran (Hormozgan). Specimens were collected using Malaise traps during 2010–2012. Eightspecies were identified of which two species, namely Glyptomorpha kaspariyani Tobias, 1976 and Vipio striolatus Telenga, 1936 are new records for the fauna of Iran. An identification key for the collected genera and species is provided.

Willow leaf beetle, Plagiodera versicolora is an important pest of willow trees that feeds on the leaves both as larvae and as adults. -Amylases (EC 3.2.1.1) are the major insect digestive enzymes that catalyze the endohydrolysis of long -1,4-glucan chains such as starch and glycogen. It can be attractive candidate to control the insect damage by inhibiting the enzyme through -amylase inhibitors. In the current study, -amylase activity was studied in the midgut of larvae and adults of P. versicolora. Amylase activity in the midgut of larvae and adults were 0.6807 and 0.1162 µmol/min/mg protein, respectively. The optimal pH for -amylase activity of larvae and adults was 4 and 8, respectively and the optimal temperature for both was 35 °C. The enzyme activity of larvae was inhibited by the addition of Na2+, K+ and Zn2+. K+ (at 5 mmol) had the most positive effect on α-amylase activity in adults. EGTA had significant influence on decreasing the enzyme activity in larvae. EDTA had the most effect on increasing the activity of the enzyme in adults. Plant amylase inhibitors play important role against insect pests. Therefore, the characterization of digestive enzymes and the examination of inhibitors on the enzyme activity could be useful in tackling insect pests.

Pseudoparasitus talebii Nemati, Malekshah-koohi & Afshari n. sp. is described and illustrated based on female specimens collected from soil in Golestan province, Gorgan region, Iran. The definition of Pseudoparasitus oudemans is revised and new definition is presented. Keywords