Journal Of Crop Protection
Volume:3 Issue: 4, Dec 2014

Entomopathogenic fungi produce a variety of degrading enzymes, including proteases, chitinases and lipases, to facilitate their entry through the massive barriers of insect cuticle. Isolates of the entomopathogenic fungi vary considerably in their proteolytic activity and virulence. The proteolytic activity of different isolates has been hypothesized to reflect their virulence toward the host. In this study, we evaluated the virulence and proteolytic activity of 17 Beauveria bassiana sensu lato isolates collected from different geographical regions in Iran. The selective medium D0C2 was used for isolating B. bassiana from soil samples. Casein substrate was used for protease assay. Total mortalities caused by different B. bassiana isolates through the dipping method, were between 25 and 60% with the highest and lowest rates for isolates BA and MITE, respectively. Our results revealed a wide variation in both proteolytic activity and virulence among the studied isolates. Additionally, we found a strong positive correlation between the proteolytic activity on Casein substrate and virulence of the isolates against the Khapra beetle, Trogoderma granarium. This finding will facilitate the screening and selection process of virulent fungal isolates as efficient agents for use in biological control programs of insect pests.

The silverleaf whitefly, Bemisia tabaci (Hem.: Aleyrodidae), is a key pest of greenhouse crops. Nymphs and adults feed on plant sap and excrete honey dew, resulting in reduction of yield quality and quantity. This pest has a high potential for developing resistant biotypes against different insecticides. Therefore, it is necessary to study the efficacy of different categories of insecticides against B. tabaci. In this research, efficacy of imidacloprid (0.5 l/ha), thiacloprid + deltamethrin (0.75 l/ha), pyrethrum (4 l/ha) andthiamethoxam + lambda-cyhalothrin (0.3 and 0.4 l/ha) with four replications were studied in a completely randomized block design in Yazd and Bushehr provinces of Iran. Mean (± SE) efficacy of imidacloprid, thiacloprid + deltamethrin, pyrethrum andthiamethoxam + lambda-cyhalothrin (0.3 and 0.4 l/ha) were 73.42 ± 3.41, 89.57 ± 2.86, 90.29 ± 2.79, 68.13 ± 3.37 and 75.62 ± 3.76 against B. tabaci nymphs 7 days after treatment in Yazd, respectively; while in Bushehr, they were 57.30 ± 3.37, 68.45 ± 4.65, 64.17 ± 2.87, 30.0 ± 4.56 and 53.0 ± 3.35, respectively. Thiacloprid + deltamethrin, pyrethrum and thiamethoxam + lambda-cyhalothrin (at 0.4 l/ha) can be suitable candidates in IPM programs of B. tabaci.

Two different microhabitats (cropped fields versus established date-palm farms) in two different cities in Khuzestan Province, Southwestern Iran, were sampled monthly during 2011-2012 in order to assess the role of anthropic uses of soil on the biodiversity of oribatid mites. A total of 17 species of oribatid mites belonging to 10 families and 15 genera were identified (nine species were collected from the fields and 17 species were collected from date-palm farm). Among the collected species, Scheloribates fimbriatus with 22% relative abundance and Acrotritia ardua with 19% were dominant species. The Shannon index of species diversity and equitability was used to analyze data. Species diversity of oribatid mites and equitability were significantly greater in the date-palm farms than in the cropped fields. Time of year had no significant effect on biodiversity.

The Mediterranean flour moth, Ephestia kuehniella Zeller, is one of the major pests in stored products worldwide. Several problems assossiated with the use of conventional insecticides have strongly demonstrated the need for applying alternative safe compounds such as insect growth regulators (IGRs). In the present study, growth regulating activity and hematological effects of pyriproxifen and methoxyfenozide were evaluated on E. kuehniella larvae. Effects of the insecticides were evaluated under laboratory conditions set at 26 ± 1 °C and 75% RH. Findings indicated that inhibition dose for fifty percent of population (ID50) was equal to 0.16 µg/mg larvae for pyriproxifen and 0.4 µg/mg larvae for methoxyfenozide, showing the considerable growth regulating effect on two-day-old fifth instar larvae. Then, influence of estimated doses were investigated on the insect hemocytes including total hemocyte count (THC) and differential hemocyte count (DHC). THC and the proportion of plasmatocytes were decreased as pyriproxifen doses increased, while, the granulocytes level was increased. In contrast, application of sublethal doses of methoxyfenozide caused a conciderable increase in THC and the plasmatocytes density, while, number of granulocytes was decreased. Since the total number of hemocytes and the proportion of plasmatocytes are very crucial in immune responses of insects, pyriproxifen could be used as an immunosuppressive pesticide in integrated control of E. kuehniella.

The present paper deals with the fauna of the subfamily Conopinae in northwestern Iran. Specimens were collected, using insect net, from Arasbaran forest, in the northwestern province of East-Azarbaijan, during 2010-2013. In total, six species belonging to two genera were identified, of which the two species, Conops longiventris Kröber, 1916 and Physocephala laticincta (Brulle, 1833), are newly recorded from Iran. The diagnostic characters and supplementary photographs of the species are provided.

The toxicity of thiamethoxam and pirimicarb on Diaeretiella rapae (McIntosh) as a parasitoid of Lipaphis erysimi (Kaltenbach), exposed to residues on glass vials, was investigated under laboratory conditions at 23 ± 2 °C, 70 ± 5 % RH and 16:8 h (L: D). Moreover, in order to find the negative impacts of both insecticides on the efficiency of D. rapae, the functional response of the exposed parasitoids were assessed. The newly emerged parasitoids were exposed to LC25 of the insecticides and distilled water as control. Host densities of 2, 4, 6, 8, 16, 32 and 64 were placed on canola seedlings in a transparent cylindrical container were offered to the treated parasitoids. Type of functional response was determined by means of logistic regression method and the parameters, attack rate (a) and handling time (Th) were calculated by nonlinear regression model using SAS software. The parasitoid exhibited type II functional response in all experiments. Attack rates in control, pirimicarb and thiamethoxam were 0.057 ± 0.01,0.059 ± 0.013 and 0.040 ± 0.01 h-1, and handling times were 1.097 ± 0.1, 1.86 ± 0.02, 2.81 ± 0.296 h,respectively. Maximum rates of parasitism (T/Th) were estimated 21.87, 12.9, 8.53 aphids, respectively. These observations suggest that pirimicarb with less harmful effects is the preferred candidate for controlling the mustard aphid.

Chrysoperla carnea is a voracious predator. It is currently mass-reared and released for biological control programs. This study was aimed at finding out the effect of different diets on biological characteristics of adult predator, and to introduce a better and cheaper artificial diet for its mass-rearing. In order to obtain a pure and physiologically homogenous population, the predator reared for seven successive generations in laboratory conditions. The effect of six different diets [a mixture of 30% concentrations of glucose, fructose and sucrose (1: 1: 1), glucose, fructose, sucrose plus extract of Sitotroga cerealella eggs (1: 1), glucose, fructose, sucrose plus extract of Anagasta kuehniella eggs (1: 1), a mixture of honey, yeast and distilled water (1: 1: 1), honey, yeast plus extract of S. cerealella eggs (1: 1: 1) and honey, yeast plus extract of A. kuehniella eggs (1: 1: 1)] was studied on biological parameters (Pre-oviposition, oviposition and post-oviposition period,longevity of males and females, fecundity, egg hatchability and eggs remained in the ovary of females after death) of seventh generation. Experiments were conducted under laboratory conditions (25 ± 2ºC, 60 ± 10% RH and 16L: 8Dh) with four replications and five observations. Results revealed that the mixture of honey, yeast and extract of A. kuehniella eggs (1: 1: 1), influenced the biological traits of the predator more effectively than all other diets. The considering average longevity, oviposition period and fecundity of female (37.73 ± 0.59, 28.57 ± 1.09 days, 795.0 ± 23.05 eggs, respectively), and egg hatchability (84.98 ± 0.71 %) compared to those of other diet treatments. Minimum pre-oviposition period (6.66 ± 0.49 days) was also found in adults fed by this diet.

Nasonovia ribisnigri (Mosely) is one of the most important pests of the lettuce plant and it was reported for the first time in Ahvaz in 2008. In order to investigate the dominant species of its natural enemies and their population fluctuations, sampling were taken arbitrarily from fifty plants twice a week during the growing season in 2010-2012. In this study, ten species of predators, three species of parasitoids and two species of hyperparasitoids were collected and identified. Hoverflies with a relative frequency of 55% were the dominant predators. Peaks of lacewings and subsequently ladybird beetles were more coincident with peaks of aphid population in mid-March in the first year of studies. But their densities in the second year were very low. Also, hoverflies and parasitoids were mainly observed in the high densities in late March-early April, in both years. Regression analysis indicated that population of aphids were mainly affected by ladybird beetles and lacewings in the first year study, as well as ladybird beetles, hoverflies and parasitoids in the second year study. Therefore, additional studies are required for further evaluation on the potential abilities of these natural enemies being a good candidate for the future biological control programs.

The effect of salicylic acid (SA) on induction of resistance against root-knot nematode (Meloidogyne javanica) and the effect of M. javanica to induce biochemical defense responses in tomato (Solanum lycopersicum L.) roots at six-leaf stage were investigated. Meanwhile, the effects of different concentrations of SA on second stage juveniles of M. javanica were examined. Biochemical assays including changes in the activity of cytoplasmic peroxidase (POX), catalase (CAT) and phenylalanine ammonia lyase (PAL) enzymes in the tomato seedlings were tested within seven days after inoculation with M. javanica in greenhouse. SA besides two treatments including soil drenching and leaf spraying were used. The efficiency of treatments were evaluated by measuring diameter of galls, number of galls per plant, number of egg masses per plant, number of eggs per individual egg mass, root and foliage fresh weight. The results showed that the activity of the enzymes (POX, CAT and PAL) increased in comparison with plants that treated with distilled water. Overall, results showed that use of SA as plant defense inducer could be effective against M. javanica in tomato roots and reduced nematode damage in greenhouse. The maximum level of larva mortality observed in 7 mM concentration of SA but had no significant difference with 6 mM concentration. SA caused 21.2% mortality of larvae at concentration of 5 mM.

Macrophomina phaseolina is one of the major yield limiting factors of melons in tropical and subtropical regions. For eco-friendly and effective management of the disease, 24 gamma induced mutants from Trichoderma harzianum 65 isolate were evaluated against three isolates of the pathogen representing three different isolates of M. phaseolina from Khorasan (isolate 1), Garmsar (isolate 2) and Khuzestan (isolate 3) isolates. The isolates of Trichoderma (mutants and wild type) were evaluated against the pathogen in dual culture and through production of volatile and non-volatile inhibitors. Maximum growth inhibition was observed in Th1, Th4, Th15, Th9 and Th22 mutants after three days. In greenhouse evaluation against M. phaseolina (isolate 1) among the inoculated treatments minimum infected plant percentage observed in Th9 treatment by 28% disease reduction as compared to infected control and among the uninoculated treatments Th1and Th9 mutants resulted in maximum growth of roots and shoots as compared to uninfected control in melon plants. These mutants are introduced as potential candidates against pathogens M. Phaseolina. The results proved that gamma-mutagenesis by improvement of the antagonistic properties of T. harzianum 65 can be useful for the biocontrol of soil borne plant pathogens such as Macrophomina phaseolina.

In order to identify the species of the family Lauxaniidae, a study was conducted in Horand region located in Northern part of East Azerbaijan province, Iran, during 2011-2013. A total of six species belonging to three genera were identified, including Calliopum caucasicum (Shatalkin, 1995) and Minettia lupulina (Fabricius, 1787) newly reported from Iran. The diagnostic characters, geographical distribution and photos of the studied species are given.

Variable rate spray applications using proportional control systems can greatly reduce pesticide use and off-target contamination of environment in orchards. Variable rate spraying of the canopy allows growers to apply pesticides only to the target, only use the correct quantity according to canopy size, season and growth stage and to apply plant protection products in an economic and environmentally sound manner. A major challenge is the reduction of agrochemicals used as Plant Protection Products (PPP) while achieving suitable deposition on the canopy. Spraying efficiency can be improved by reducing the spray losses associated with deposition on the ground and off-target drift. Adjustment of application rate proportional to the size and shape of tree crops has shown high potential for reducing agrochemicals in automatically controlled sprayers. In recent years target detection methods have been developed by using advanced techniques such as vision and laser scanning systems or simpler ultrasound, infrared and spectral systems. These systems have made it possible to develop geometric maps of trees allowing site-specific management of orchards. Variable rate spraying can thus be utilized as a methodology for applying the required amount of PPP’s to the canopy while preventing over dosage as well as drift. Utilization of sensors to monitor canopy, distances and location ensures better use of expensive inputs, resulting in a sustainable approach to an important practice. Various methodologies available for determination of canopy structural parameters and introduces of some applicable commercial systems as well as pointing out their similarities and differences.

A total of 29 species in 16 genera and 8 subfamilies of the braconids (Hym., Braconidae) were collected from Bahariya and Farafra oases (Western Desert, Egypt) in alfalfa fields, Medicago sativa L. These species were identified, together with details of the sites where they were found and an indication of their relative abundance in each site. From the samples, 4 species in 4 genera and 3 subfamilies are recorded as new to the Egyptian fauna. These are: Aphidius asteris Haliday, 1834, Ephedrus plagiator (Nees, 1811) (Aphidiinae), Homolobus (Chartolobus) infumator (Lyle, 1914) (Homolobinae) and Opius lugens Haliday, 1837 (Opiinae). Thirteen braconid species are also newly recorded in association with alfalfa fields: A. asteris; Praon necans Mackaeur, 1959 (Aphidiinae); Habrobracon hebetor (Say, 1836) (Braconinae); Chelonus basalis Curtis, 1837; Ch. blackburni Cameron, 1886; Ch. oculator (Fabricius, 1775); Phanerotoma leucobasis Kriechbaumeri, 1894 (Cheloninae); Dinocampus coccinellae (Schrank, 1802) (Euphorinae); H. (C.) infumator (Lyle, 1914) (Homolobinae); Apanteles appellator Telenga, 1949; Cotesia glomerata (Linnaeus, 1758) (Microgastrinae); Psyttalia concolor (Szépligeti, 1910) and P. nilotica (Schmiedeknechti, 1900) (Opiinae).

Haplothripsverbasci (Osborn) is recorded from Iran for the first time. The specimens of this species were collected on flowers of Verbascum thapsus (Scrophulariaceae) from Hamedan Province, western Iran.

Shot hole caused by Wilsonomyces carpophilus is one of the main constraints to prune fruit production in Iran particularly in Khorasan Razavi province. Causing foliage shot hole in spring and early summer; fruit-spotting and cankers on limbs and twigs during autumn rains. The fungus was isolated from the lesions of twigs and was purified on PDA. The pathogenicity and virulence on detached twigs of six different stone fruit tree species was examined in vitro. The virulence of isolates as measured by lesion length was significantly different among the isolates obtained from different host species. In contrast to other hosts, sour cherry did not show any canker on shoots or twigs and disease progress was just as tissue colonization by the fungus hyphae. Mean comparison was carried out with LSD test (α = 0.05) and did not have any significant difference. The most sensitivity of shoots to infection was related to peach (MS = 12.467) and located at A group among stone fruit species. The results of bud and shoot evaluations indicated that the fungus overwinters as hyphae and conidia in buds, and in the form of hyphae as well as thick-walled globular chlamydospore in twigs. Additionally, viability of recovered conidia ranged from 33 to 90% throughout the dormant season. A better understanding of disease life cycle leading to improved monitoring of the fungal disease will reduce fungicide applications.