a. golizadeh

Potato tuber moth, Phthorimaea operculella (Zeller), is the most important pest in potato fields in the world and Iran. The use of appropriate agricultural and protection strategies to prevent oviosition of Ph. operculella on newly formed potato tubers at the end of the cropping season can be effective in reducing its damage. The effects of cover crops on damage reduction on newly formed potato tubers were investigated in a randomized complete block design with three replications during two years 2020 and 2021. After the senescence of potato foliage, the cover crops including of vetch (Vicia sativa), grass pea (Lathyrus sativus), rye (Secale montanu), and strengthening of the natural field vegetation were used as cover crops in the field. Tuber infestation (%) during two years in vetch, grass pea, reinforcement of field vegetation and rye was 8.00, 12.33, 26.33 and 26.17%, respectively and all treatments significantly reduced the damage on potato tubers when compared with control (39.17%). The number of larvae in the infested tubers showed a significant difference between treatments, and the treatments of vetch, grass pea, reinforcement of field vegetation and rye showed a lower larval density, respectively. Based on results, vetch is the most effective plant to cover the soil and prevent Ph. operculella oviposition on the potato tubers. Moreover, maintaining and strengthening of weeds in the field at the end of the growing season and after the drying of potato foliage could be a low-cost method to prevent damage by Ph. operculella on tubers in the soil.

The Greenbug, Schizaphis graminum Rondani (Hemiptera: Aphididae), is one of the most important pests in grain, especially wheat, and is an important cause for transferring a number of pathogenic viruses in plants. The purpose of this research was to evaluate the lethal and sublethal effects of Pymetrozine insecticide on life history parameters and α-esterase and β-esterase enzymes activity of S. graminum. Detoxifying enzymes play a vital role in the detoxification of chemical compounds in many living organisms. These enzymes increase the resistance of insects to chemical pesticides by the catalysis of these compounds in their body.

The S. graminum was reared on the wheat host in a growth chamber set at 25 ± 2 °C, 60 ± 5 % RH, plus 16: 8 (L: D) hour photoperiods. Daily observations and records were made for the development period and survival rate. The crude data were analyzed based on age-stage and two-sex life table analysis. TWO SEX-MSChart was used to evaluate the raw data based on the age-stage and two-sex life table. In addition, alpha-naphthyl (α-NA) and beta-naphthyl (β-NA) acetates were employed as substrates for the α-esterase and β-esterase activity, respectively. Esterase enzymes of tested treatments were measured using a microplate reader.

Exposing adults to bioassays indicated that the lethal concentration (LC50) of insecticide treatment in S. graminum adults was 84.68 mg a.i./L. The present study demonstrated that Pymetrozine insecticide showed more acute toxicity on adult stages of S. graminum. Moreover, exposure of adults to sublethal concentrations (LC30) negatively affected the development and reproductive characteristics and demographic factors of the Greenbug. In specific, results for sublethal experiments showed a significant increase in the development time of the pest on the insecticide treatment compared with the control. On the contrary, the lowest fecundity in pests was observed on Pymetrozine insecticide. In addition, the tested insecticide significantly reduced the population growth parameters of S. graminum, which can be identified using detoxifying enzymes as biochemical markers of the pest. Estimation values for the intrinsic rate of increase (r) in the control and insecticide treatment were 0.394 and 0.280 per day, respectively. Furthermore, the activity of alpha and beta esterase was not significantly different between control and insecticide treatment.

The results revealed that Pymetrozine insecticide exerts high lethal and sublethal effects on S. graminum, and thus, it is recommended to be applied in an integrated pest management program (IPM). Semifield and field studies are needed to obtain more applicable results using insecticides.

Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae) is an important parasitoid of lepidopterous pests, particularly the larval stage of Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae), which is a polyphagous and key pest. The host plant of the herbivore can have a significant effect on their parasitoids' biological properties and efficiency. Host plants have a direct impact on the biological parameters of the herbivores. Additionally, they can influence the development and reproductive characteristics of herbivores' natural enemies. The purpose of this study was to determine the effect of seven host plants on the life history of V. canescens, including apple, date, olive, orange, pistachio, pomegranate, and quince, as well as an artificial diet.

scanescens was grown on each host in a growth chamber set to 30±1°C, 60±5% RH, and photoperiods of 14:10 (L:D). Daily observations and records of stage duration, developmental period, and survival rate were made. The raw data were evaluated using TWO SEX-MSChart based on the age-stage, two-sex life table. Moreover, we used a spectrophotometer to determine the phytochemical metabolites of the tested hosts. Correlations between demographic variables and biochemical characteristics of various hosts were then estimated to identify factors affecting tritrophic interaction.

The results indicated that various hosts had a significant effect on the demographic characteristics of the V. canescens. The immature development period was the longest and shortest on quince and artificial diets, respectively. Additionally, V. canescens' intrinsic rate of increase (rm) was lowest on quince and highest on an artificial diet. Furthermore, significant differences in biochemical metabolites were observed in this study between the various hosts. Moreover, significant positive or negative associations were discovered between life history variables and the biochemical characteristics of various hosts. The time required for parasitoid development was positively correlated with the phenol, tannin, and flavonoid content of E. ceratoniae hosts tested. There was a significant negative correlation between the total phenolic content, tannins, and flavonoids of various hosts and the fecundity, net reproductive rate (R0), and intrinsic rate of increase of V. canescens.

Our findings may provide basic information for a comprehensive understanding of the tritrophic interactions between plants, herbivores, and parasitoids. Combining host plants and biological control agents may be an effective integrated pest management strategy for E. ceratoniae and other lepidopterous pests. Most importantly, our findings indicated that host plant quality variations could impact the performance and multitrophic communication behavior of V. canescens.

The carob moth, Ectomyelois ceratoniae Zeller (Lep.: Pyralidae), is a polyphagous and destructive pest that causes considerable damage to various crops worldwide both before and after harvest. Host plant resistance is a critical component of integrated pest management and can be beneficial when used in conjunction with biological and chemical pest control approaches. The host type has a substantial effect on the biological characteristics and population growth parameters of E. ceratoniae. The purpose of this contribution is to evaluate the impact of eleven hosts, including peanut, apple, date, fig, olive, orange, pistachio, pomegranate, quince, and walnut, on the life history and nutritional indices of this pest.

The carob moth larvae were reared on each plant host in a growth room set at 30 ± 1 °C, 60 ± 5 % RH, plus a 14:10 (L:D) hour photoperiod. Daily observations and records were made of the duration of each stage, developmental period, and survival rate. TWO SEX-MSChart was used to evaluate the raw data based on the age-stage two-sex life table. Additionally, hosts' phytochemical metabolites were measured using a spectrophotometer. Correlations between demographic factors and nutritional properties with biochemical features of various hosts were then estimated.

The results indicated that various hosts substantially affected E. ceratoniae's demographic characteristics and nutritional indices. On walnut and artificial diets, the immature development period was the longest and shortest, respectively. Additionally, the intrinsic rate of increase (r) of E. ceratoniae was lowest on quince, orange, apple, olive, and highest on an artificial diet. Compared to larvae fed on other hosts, larvae reared on an artificial diet had the highest efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD). Furthermore, larvae-fed pistachio had a greater relative growth rate (RGR) than other tested hosts. The cluster analysis findings revealed that pomegranate and artificial diet treatments were relatively vulnerable hosts, whereas quince, orange, apple, and olive were the least suitable (most resistant) hosts for E. ceratoniae feeding. Significant variations in biochemical metabolites were observed between the various hosts in this study. Moreover, significant positive or negative associations between life history variables and nutritional indices plus biochemical features of various hosts were found. A significant negative correlation was observed between total phenolic content and total anthocyanin content of different hosts and E. ceratoniae fecundity, net reproductive rate (R0), intrinsic rate of increase (r), the efficiency of conversion of ingested food (ECI), and relative growth rate (RGR).

The findings may provide essential information for a better understanding of plant-herbivore interactions, which may aid in the development of effective integrated pest management (IPM) strategies for E. ceratoniae control.

Vegetable leafminer, Liriomyza sativae Blanchard, is one of the most important pests of cucumber, especially in greenhouses. In this study, effect of different fertilizer treatments, including vermicompost, humic acid, nitrogen, vermicompost-humic acid and vermicompost-humic acid-nitrogen mixture, were investigated on biological parameters of vegetable leafminer along with some growth indices of cucumber plant including plant height and chlorophyll content. The experiments were carried out in a growth chamber at 25 ± 2˚C, relative humidity of 65 ± 5 %, and a photoperiod of 16 L: 8 D. Based on the results, the duration of immature stages and longevity of adults were significantly different on the tested treatments. Duration of immature stages was highest on humic acid treatment (3.36 d) and lowest on control (3.13 ± 0.06). Furthermore, the lowest values of longevity and life span of adults were recorded on humic acid (6.57 and 27.21 d, respectively) and the highest values of these parameters were on nitrogen treatment (11.14 and 30.11 d, respectively). The tested treatments had significant effects on population growth parameters of the pest. The highest values of intrinsic rate of natural increase (r) and net reproductive rate (R0) of the vegetable leafminer were on nitrogen treatment (0.1640 d-1 and 52.70 offspring/female, respectively) and the lowest values of these parameters were on humic acid treatment (0.0888 d-1 and 9.67 offspring/female, respectively). The results of the present study showed that humic acid can be used in integrated management of the vegetable leafminer in cucumber growing area.