فصلنامه گیاه پزشکی
سال چهل و پنجم شماره 1 (بهار 1401)

Macrochelidae are cosmopolitan free-living predators that inhabit habitats rich in decaying organic matter, such as manure. They feed primarily on small arthropods and nematodes. Macrochelidae predators are considered beneficial mites that have been identified as promising biological control agents for fly eggs and larvae, and other harmful organisms. Adult Macrocheles muscaedomesticae (Scopoli) prefers house fly Musca domestica L. eggs to first instar larvae. This predator has been observed to reduce fly populations in natural conditions significantly, and the reduction was considerably greater when the predator was augmented. The purpose of this study was to determine the effect of mutual interference on M. muscaedomesticae predation on house fly eggs at 27 ± 1°C and 33 ± 1°C.

In this study, we investigated the mutual interference of adult female predators M. muscaedomesticae on house fly eggs in an incubator at two constant temperatures of 27 ± 1°C and 33 ± 1°C, 65 ± 5% RH, 14:10 h (L: D) photoperiod. To this end, the per capita searching efficiency and per capita predation of 1, 2, 4, and 8 female mite M. muscaedomesticae were determined, and 100 house fly eggs were offered to 4-day-mated adult female mites in each predator density for 6 h. Before the experiments, female predators were fed and mated for 48 h and then starved for 24 h to obtain a cohort of M. muscaedomesticae.

A significant relationship was discovered between the logarithm of predator density and M. muscaedomesticae per capita searching efficiency. This dramatically decreased per capita predation rate and per capita searching efficiency as predator density increased at both temperatures. At 27 °C, once predator densities were increased from 1 to 8, per capita predation decreased from 16.70 to 4.69, and per capita searching efficiency decreased from 0.183 to 0.058. At 33 °C, when predator densities were increased from 1 to 8, per capita predation decreased from 9.20 to 4.81, and per capita searching efficiency decreased from 0.097 to 0.061.  

The negative slope of the regression line or interference coefficient of -0.6774 and -0.2448 at 27 and 33 °C, respectively, indicated that interference is a density-dependent factor and that per capita searching efficiency exhibits negative density-dependency. As a result, different predator densities may affect M. muscaedomesticae's efficacy. The findings could be applied to the mass rearing techniques of this predator mite in an insectarium.

Aenasius bambawalei Hayat (Hymenoptera: Chalcidoidea: Encyrtidae) is a solitary endoparasitoid of Phenacoccus solenopsis Tinsley. It was first found in Iran in 2011 following the introduction of its host, P. solenopsis, in the country in 2009. In order to confirm the identification of A. bambawalei which was based on classic taxonomy, the mitochondrial cytochrome oxidase I (COI) gene was sequenced in A. bambawalei samples collected from southern Iran. The parasitoids were retrieved from the specimens collected from four provinces of Iran, namely Khuzestan, Bushehr, Hormozgan and Fars. The polymerase chain reaction was performed according to standard protocols on the extracted DNA to amplify a fragment of the COI gene. Obtained 633 bp COI sequences were aligned with five A. bambawalei COI sequences available in GenBank from China and Pakistan and two other sequences as outgroups. In addition, a dendrogram was prepared and graphically depicted in a neighbor-joining tree. Our identifications were confirmed by the matches between our sequences and those of the GenBank database. Sequences displayed a BLAST hit and had a sequence similarity percentage of 99%-100% with the GenBank sequence assigned to the same species. The results of COI sequence analysis were in agreement with the morphological identifications. The findings of this study pointed out that COI gene sequence data is a precise and accurate tool for the rapid identification of A. bambawalei species.

The Black bean aphid (BBA), Aphis fabae Scopoli (Hemiptera: Aphididae), is an important pest of agricultural and ornamental plants. Entomopathogenic fungi are important factors in the microbiological control of pests that are considered a good alternative for chemical insecticides. Isolation of novel potential IPF and evaluation of their efficacy against pests are primary steps for achieving a successful microbiological control program. In this study, the efficacies of three Iranian isolates of Akanthomyces lecanii (PAL6, PAL7, and PAL8) and an Iranian isolate of A. muscarius (GAM5) which had been isolated from two hemipteran pests, Pulvinaria aurantii Cock. and Aphis gossypii Glover, respectively, in citrus orchards of west Mazandaran (North of Iran), were evaluated against BBA.

Mortalities of the BBA nymphs and adults caused by different conidial concentrations (104, 105, 106, 107 108 conidia/ mL) of each fungal isolate during other days after treatment (DAT), 1–7 DAT, were determined under laboratory conditions.

All isolates were pathogenic to the aphid causing about 25% mortality. The efficiency of the isolates was not significantly different among the aphid life stages. When the isolate concentrations (up to 55%) and DAT (up to 53.13 times) increased, their effects increased significantly. The highest and lowest mortality rates were observed at concentrations 108 (12.83%) and 104 (5.86%) conidia/ mL, respectively. The highest effectiveness was recorded in seven DAT for all isolates, 15.14% mortality. At one DAT, the isolates caused about 1% mortality in the aphid population with the lowest effectiveness. The highest mortalities were observed for GAM and PAL7 isolates at six DAT, i.e., 16.83 and 16.67%, respectively. Furthermore, the lowest effectiveness was recorded for the isolates GAM and PAL7, at one DAT (<0.1% mortality), respectively.

The isolates had some potentials for microbiological control of the BBA. Time and conidial concentrations, are the critical factors determining the efficacies of the entomopathogenic fungi. The highest effectiveness can be achieved before six DATs. When the conidial concentrations increased, the obtained mortality by the isolates was enhanced. Due to the relatively low efficacies of the EPF and a lag time for getting sufficient mortality, integrated applications of the entomopathogenic fungi with other compatible control agents with faster effects such as biorational insecticides are recommended. However, the laboratory results should be supported with field or semi-field studies before recommending applications of the entomopathogenic fungi against the BBA aphids in greenhouse or field crops.

The date palm fruit stalk borer, Oryctes elegans Prell (Coleoptera: Scarabaeidae), is one of the most destructive endemic pests of palm groves in Iran. Recently, there has been a trend toward using kairomone or pheromone trapping as a preferred method of controlling this borer to preserve and protect the environment. The current field study examined the effects of trap density (6 or 10 traps/ha) and trap color (black, white, red, and yellow) on the attraction of adults of O. elegans to a Kairo-pheromonal diffuser (Ferrolure manufactured by Econex Ltd, Spain) in four infested date palm groves in Shalheh-ye Emam Hasan, Abadan, southwestern Iran. Among the test density, 6 traps/ha could accurately detect the presence of adults of O. elegans in the field and help monitor O. elegans. However, 10 traps/ha caught significantly more adults than 6 traps/ha. At both densities, trap colors significantly affected adults' mobility and dispersal to traps. The black traps captured the most significant number of adults in the field, followed by the yellow, red, and white traps. In addition, there was no significant difference between the total numbers of adults captured in traps with different colors during four different times of sampling. As a result, the black traps with 10 traps/ha yield better results at capturing in the field. Our results provide the basic information for developing a safe mass trapping system to control O. elegans.

Maize (Zea mays L.) is the third most important crop after wheat and rice, restricted by various pathogens including viruses. So far, it has infected more than 40 species of viruses with the different genera of maize, some of which are globally distributed which can cause severe damage to the crop. Maize Iranian mosaic virus (MIMV), Maize dwarf mosaic virus (MDMV) and Wheat streak mosaic virus (WSMV) are some of the most common viral diseases worldwide and in Iran. The significance of Khuzestan province in the country's maize production necessitates research of the viral infection rates among planted hybrids in the area.

Based on a survey was conducted during 2020-2021, 48 farms cultivated with different maize hybrids named Single Cross 704, Single Cross 703, Jovein 704, Moghan 704, Faraz, Afarin, Korduna, Syngenta and AS 71 in three counties of Dezful, Andimeshk and Shousha. The leaves of the plants that showed the signs of yellowing, mosaic and shortening were collected and transferred to the Jihad Agricultural Laboratory of Khuzestan province. In these samples, ELISA (Enzyme-linked immune sorbent assay, ELISA) was performed with specific polyclonal antibodies.

The results showed that among 480 samples examined, 43% of the samples were infected with MIMV and MDMV viruses, but no mixed infection of these two viruses was found among the samples. The highest percentage of infection (30٪) was related to MIMV. This is the first report of MIMV in Khuzestan province which was found in all three cities. Faraz hybrid showed the highest sensitivity to the MIMV. MDMV and WSMV showed 13٪ and 3٪ incidence rate, respectively. MDMV was found only in Andimeshk and among Single cross 703, Single cross 704 and Jovein 704 hybrids, among them Jovein 704 showed the highest sensitivity. MDMV has a strong serological relationship with Bermuda grass southern mosaic virus (BgSMV). Thus, in the future studies, the infected samples should be examined by PCR using specific primers. WSMV is a common virus in wheat fields which was not detected in Iranian maize fields. In this study, for the first time, the presence of this virus was found in Korduna hybrids, Single cross 703 and Single cross 704 in Andimeshk.

The wheat aphid, Schizaphis graminum Rondani, is one of the most important pests of wheat that damages this crop by feeding on vegetable sap. Among its natural enemies, ladybug Hippodamia variegata (Goeze) is the most active predator of this pest. The application of wheat fields may affect the population of these insects. The present study investigates the effect of common wheat herbicides on wheat aphids and their predator (i.e., ladybug H. variegata).

In the present study, the lethal effects of four herbicides (i.e., Clodinafop-propargyl, Tribenuron-methyl, 2,4-D plus MCPA, and Mesosulfuron-methyl+ Iodosulfuron-methyl-sodium) versus untreated types(control) was examined on the green wheat aphid S. graminum and its predator H. variegata using a completely randomized design under laboratory conditions at 25±1oC, 60±10% RH, and 16:8 hours (L: D). The individuals were transferred from infested wheat to fresh plants every week to keep an appropriate aphid colony. After reproducing several generations on the potted plants, the adults were considered for experiments. Adult specimens of H. variegate were directly collected from the same aphid colony using an aspirator and transported to the laboratory.The leaf-dip method was employed to evaluate the herbicide’s lethal effects. Besides, the mortality rates were recorded 24, 48, and 72 hours after the treatment process. Experiments were replicated for each herbicide four times. In this case, each replication included ten adult insects as subjects.

The results showed that using Mesosulfuron-methyl+ Iodosulfuron-methyl-sodium on aphids killed all insects in the first 24 hours of the experiment. Clodinafop-propargyl plus Tribenuron-methyl caused mortality rates of 55, 70, and 92.5% at 24, 48, and 72 hours post-treatment, respectively. In the case of 2,4-D plus MCPA, the mortality rates were 20, 37.5, and 57.5% after 24, 48, and 72 hours of the experiment. Mesosulfuron-methyl+ Iodosulfuron-methyl-sodium causes lady bug mortality rates of 45, 52.5, and 57.5% after 24, 48, and 72 hours, respectively. These valuesfor Clodinafop-propargyl plus Tribenuron-methyl were 17.5, 37.5 and 45%, while 2,4-D + MCPA caused 12.5, 15, and 27.5% mortality rates on ladybugs. Therefore, the present study recommends Mesosulfuron-methyl+ Iodosulfuron-methyl-sodiumto implement weed control in wheat fields and control S. graminum. Also, it is suggested to utilize Clodinafop-propargyl + Tribenuron-methyl and 2,4-D + MCPA in combination with biocontrol (using H. variegata) to perform the relative control of wheat aphids.

Agricultural herbicides can affect various insects such as pests and natural enemies. This procedure occurs through their direct toxicity or their effects on the population and diversity of their plant hosts. The present study is one of the few studies that simultaneously investigate the influence of herbicides on a pest and its natural enemy. The findings demonstrated that herbicides could directly affect insect populations. The principal purpose of the present study was to determine whether common and widely used herbicides in the cultivation of wheat in Iran can directly cause death in adults of aphids and their main predator (H. variegata). Since both of them have a high population in most wheat fields, their adults were simultaneously established and activated in the wheat farms during herbicides. Based on the recommended concentrations and direct application, four herbicides caused death in adults of green wheat aphids and ladybugs.

Cydia pomonella is one of the most important pests of apple orchards in Iran and the world. Its damage to apples is of considerable economic importance, as it reduces the quantity and quality of fruits. The larvae of this insect do the most harm, and the larvae eat mostly on apple seeds, but it also feeds on apple flesh tissue until it reaches the seeds. Sex pheromone plays an important role in tracking and controlling this pest, so using pheromone traps to get the best spraying time and prevent indiscriminate spraying is inevitable.

In this study, the population changes and determining the peak time of flight in different generations of Cydia pomonella in the gardens of Kohsorkh region of Khorasan Razavi province were investigated. As a result, four pheromone traps were set up in the region's apple orchards in 2018, and the number of insects caught in the traps was counted at regular intervals.

 According to the observations, the time of the emergence of adult insects of this pest was in the first decade of May, and their flight continued until the first decade of October. The apple worm moth had four peak flight points. Studies conducted in this study showed the existence of four generations for this pest in the Kohsorkh region.

Two damaging generations of codling moth is recognized, one in late spring (after petal fall) and the other in midsummer. Feeding by the larvae of the latter causes most fruit damage. Using pheromone traps containing the sex attractant of the female moth can improve treatment timing. Insecticides are most effective when administered 10 to 14 days after peak flights are identified in pheromone traps using this method. The findings of this research revealed the four peaks of complete insect flying. The first flight peak emerged on 17 May, followed by a sharp decrease to the second flight peak on 14 June. After this peak, in terms of warmer weather, the activity of the pest was reduced. The trap hunting process decreased, and in the period from June 20 to July 14, it remained unchanged and reached zero. The third happened; then, the hunting continued with fluctuations and finally on September 8, the fourth peak of the flight was observed. After the last peak, regarding the gradual decrease of temperature and lowering of the average temperature from the minimum thermal threshold, the flight activity of moths decreased and from 10 October onwards, the trap hunting stopped. The third and fourth generations had the highest hunting rate and the first and second generations had the lowest hunting rate.

The effects of plant growth-promoting activities involving biological, chemical, and organic fertilizers are partly well studied for pest insects. Still, studies concentrating on the impacts of such treatments on predators are uncommon. Plant growth promoting treatments- biological, -organic and -chemical fertilizers alter the biochemical composition of plants, which can impact the multitrophic interactions. Beneficial soil microorganisms such as plant growth-promoting rhizobacteria (PGPR) can affect nutritional quality, secondary metabolites, enzymes, phytohormones, and volatile organic compounds (VOCs) of plants, which may influence host plant-insect herbivore- natural enemies interactions. The predatory ladybird, Adalia bipunctata, is polyphagous species that mainly feed on aphids, especially the green peach aphid, Myzus persicae. It is a polyphagous insect that can cause damage to a lot of crops in fields and greenhouses. There is no published research concerning the effects of various plant growth-promoting on physiological performance of A. bipunctata. Thus, we investigated the impacts of various plant growth promoting treatments, viz. no fertilizer (untreated control), one type of PGPRs, vermicompost 30% (v/v), and zinc sulfate on physiological performance of A. bipunctata through M. persicae reared on treated Capsicum annum L. (Solanaceae).

Bell pepper seeds of the California Wonder cultivar were developed in 3L plastic pots and were used in bioassays when they reached 4-6 leaf stage under greenhouse conditions. Then, aphids were obtained from tomato farms from Meshkin-Shahr (Ardabil, Iran) and transmitted to bell pepper grown in the greenhouse. To keep an appropriate sub-sucking colony, every week the individuals were transferred from infested bell peppers to fresh plants. Adults of A. bipunctata were obtained from alfalfa farms of Ardabil, Iran, and transmitted to the laboratory, in a growth chamber. Mating pairs were selected and kept together in separate plastic jars (6 by 12 cm2) and were reared on pepper plants infested with sub-sucking insects as prey. In the study, the effect of spraying zinc sulfate on bell pepper plants and addition of the organic fertilizer of vermicompost 30% and the biologic fertilizers of Bacillus subtilis to the growing medium of bell pepper on the activities of critical physiological processes of A. bipunctata fed on M. persicae using a completely randomized design under greenhouse conditions. Then 5 adult predators were randomly selected from each treatment and homogenized with a hand pounder in 1 mL pure ice-cold water. After that, the specimens were centrifuged at 13,000 g pending 15 min at 4 ◦C. The top layer was collected and kept at 20 ◦C during biochemical analyses. All physiological enzymes assay based on the defined method were conduted in three biological replications. Then, data were analyzed using a one-way analysis of variance (ANOVA) followed by the Tukey test with the MINITAB software.

The results demonstrated a significant difference among the digestive enzymes activities, intermediates, and storage compounds of the predatory ladybug reared on aphids fed on bell peppers treated with different fertilizers. The lowest total protease activity of ladybird was observed in the control compared to other treatments. The elastase activity of ladybug increased on B. subtilis compared to other treatments. The highest and lowest amounts of cathepsin B activity in ladybugs were recorded on B. subtilis and vermicompost 30%, respectively. The highest and lowest low density lipophore (LDL) values were observed in A. bipunctata on control and B. subtilis treatment, respectively. Predatory ladybug had the highest protein, triglyceride, and glycogen on B. subtilis compared to other treatments. The lowest triglyceride and glycogen was also observed on vermicompost 30%.

Plant-herbivore interactions under the influence of bio-fertilizer have led to increased digestive enzymes activity and storage compounds in ladybug, which could be used in combination with the use of biological control agents in integrated management programs of the green peach aphid in greenhouses.

Entomopathogenic nematodes (EPNs), in the genera Steinernema and Heterorhabditis, are potent biocontrol agents that are widely used against various insect pests. The non-feeding and non-developing third stage infective juvenile (IJ), or the dauer juvenile, is the survival stage of EPNs that is able to survive outside the host and is used for formulation. In recent years, alginate has been recognized as the most promising biopolymer in the formulation of living cells and microorganisms. According to the results of scientific research, native isolates of each region have a greater impact than non-native and foreign isolates due to high ecological compatibility.

The native isolate of Steinrnema carpocapsae IRMoghan1 from the Moghan region, with accession number MF187616 in the NCBI database, was selected for use in the alginate-based formulation owing to its high potential of survival and pathogenicity. The best and most cost-effective capsule composition was selscted by evaluating 0.5%, 1%, 2%, and 3% alginate concentrations with 0.5%, 1%, and 2% concentrations of a calcium chloride solution. Formulation characteristics, the survival rate of the nematodes inside the formulation, exited water volume, escaped nematode rate, and pathogenicity of the formulated nematodes against Galleria mellonella larvae as the laboratory host were measured and recorded during 4 to 90 days post formulation. The analysis of variance (ANOVA) and comparison of means by Duncan’s test were performed on data using SAS software.

Based on the results, the best concentrations for sodium alginate and calcium chloride were 2% and 0.5%, respectively, which were therefore selected for the next experiments. The diameter of the formed capsules ranged from 3.5 to 4.5 mm. The ANOVA of the amount of water leaving the capsules, the number of nematodes escaped from the capsules, and the survival rates of the nematodes inside the capsules were significantly different at various time intervals post formulation (P ≤ 0.01). Statistical analysis showed that the formulated nematodes had a higher survival rate than the unformulated congeners in all the time points from (4 to 90 days) after formulation. The results of the ANOVA for bioassay experiments showed significant differences between different time points in the percentage of mortality of G. mellonella (P ≤ 0.01).

The present study showed the high potential of S. carpocapsae IRMoghan1 native isolate for sodium alginate formulation and, the successful formulation of an entomopathogenic nematode as a biocontrol agent, which is a valuable finding as it increases the shelf life without refrigeration. This finding should be used as the basis of further studies for the commercialization of this isolate.

It is necessary to investigate side effects of the pesticides on natural enemies of pests for integrated pest management (IPM) programs. Insecticides may impair physiological and behavioral traits of parasitoid wasps. This research was designed to study toxicity of actamiprid, pymetrozine and flonicamid on Aphidius matricariae Haliday (Hym.: Braconidae: Aphidiinae), a parasitoid wasp of Aphis fabae Scopoli (Hemi.: Aphididae). Furthermore, their sublethal effect were evaluated on the functional response of the parasitoid wasp of under laboratory conditions (25±1 0C, 65±5% R.H. and 16:8 (L: D) h).

A residual bioassay method was used to determine the toxicity of the insecticides on A. matricariae. Adult parasitoids were exposed to LC25 of the insecticides and distilled water as control on the glass vials and functional response study was done. After 24 h, randomly selected 6 alive mated females were transferred individually to cylindrical containers containing broad bean seedlings infested by densities of 2, 4, 8, 16, 32 and 64 of the third instar A. fabae nymphs. Each host density had fifteen replications. Aphids were left on the plants until mummification of the parasitized individuals. Functional response type was determined using logistic regression and its parameters were estimated by non-linear regression using SAS program.

The LC50 of values of actamiprid, pymetrozine and flonicamid were 3.07, 740.20 and 133.15 mg a.i./l, respectively. The results showed that acetamiprid was more toxic than pymetrozine and flonicamid to adult stage of A. matricariae. Functional response of the parasitoid on control and the insecticides treatments fitted the type II. Attack rate (a) in control, actamiprid, pymetrozine and flonicamid treatments were estimated 0.0432 ± 0.01, 0.0237 ± 0.003, 0.0414 ± 0.004 and 0.0398 ± 0.01 h-1 and handling time (Th) were 0.5170 ± 0.06, 1.4257 ± 0.13, 0.6133 ± 0.05 and 0.6816 ± 0.07 h, respectively. The attack rate (a) value of A. matricariae exposed to acetamiprid was significantly lower than that of control and other insecticides treatments. The highest value of handling time(Th) was observed in acetamipirid. Although, they were not significantly affected by pymetrozine and flonicamid. Maximum rates of parasitism (T/ Th) in control and mentioned insecticides treatments were estimated 46.42, 16.83, 39.15 and 35.21 aphids, respectively.

According to present results, acetamiprid negatively affected the attack rate (a), handling time (Th) and maximum attack rate (T/Th) of parasitoid compared to the control, pymetrozine and flonicamid treatments. Pymetrozine and flonicamid had lower side effects on A. matricariae in comparison with acetamiprid and they were suitable candidates for controlling of A. fabae in combination with A. matricariae. Although, studying side-effects of the insecticides on the mentioned parasitoid wasp in semi-field and field conditions are needed to obtain more applicable recommendations.