The tomato leafminer, Tuta absoluta (Meyrich) (Lepidoptera: Gelechiidae), is a serious pest of tomato crops worldwide. The intensive use of chemical pesticides to control it has led to the selection of resistant populations. This study investigated the resistance of T. absoluta populations to pyrethroid and the organophosphate insecticides from ten regions of Iran. The resistance ratios at LC 50 for chlorpyrifos and diazinon varied among populations from 4.3 to 12 and from 1.4 to 9.0, respectively. The resistance ratios of the pyrethroids cypermethrin, deltamethrin and permethrin varied from 1.3 to 3.7, 2.7 to 13 and 1.2 to 4.3, respectively. Inclusion of synergists in toxicological bioassays and the variation observed in the activity of esterases, glutathione S-transferase and cytochrome P450-dependent monooxygenase suggest the existence of metabolically based resistance. Esterase and P450 biochemical assays were positively correlated with deltamethrin, and cypermethrin tolerance and diazinon tolerance correlated with esterase activity. The genes encoding the organophosphate and pyrethroid target sites acetylcholinesterase (ace1) and sodium channel (kdr) were partly sequenced. The genotyping revealed mutations in high frequencies in all populations leading to an A201S substitution in ace1 and three substitutions in the sodium channel gene L1014F, M918T, T929I. In summary, our results indicate the presence of organophosphate and pyrethroid resistance in Iranian T. absoluta populations with involvement of both detoxification enzymes and target site alterations. Most likely the populations of T. absoluta imported to Iran were resistant upon arrival. K E Y W O R D Sacetylcholinesterase, insecticide resistance, knock-down resistance, metabolic resistance, target site mutation, Tuta absoluta

Although Cacopsylla pyri Forster and Cacopsylla pyricola Linnaeus have long been considered as more significant pests of pear trees around the world, Cacopsylla permixta Burckhardt and Hodkinson is the most significant pest in some parts of Iran, especially in pear gardens of Karaj. Current control strategies against this pest in Iran generally involve five or six insecticide treatments each year, despite unsatisfactory results are reported at many localities. So, it is crucial to know the most susceptible generation of the pest to apply a good strategy for its control. The aim of this study was to explore the seasonal variation in susceptibility of C. permixta to four commonly used insecticides. The results showed that winter forms (February) were 2.71‐fold, 4.58‐fold, 3.26 fold and 3.38‐fold more tolerant to diazinon, imidacloprid, acetamiprid and abamectin, respectively, compared with summer forms. Also, Esterase, GST and P450 monooxygenase activity was highest during February. Moreover, the content of lipid, carbohydrate, glycogen and protein was significantly higher in February compared with other months. Based on these results, the best period for insecticide treatment for efficient control is treatment against the first generation, at the time when eggs are laid by females as well as during the egg hatching and the larvae appearance. At this time of year, psylla are more susceptible, which would likely lead to better results and the reduction in damage during the next summer. However, further studies are needed to test this in farm settings, and to whether this holds true for other psylla species.

The tomato leafminer, Tuta absoluta is a serious pest of tomato crops worldwide. In this study the effect of sublethal concentrations of abamectin (at 10 and 30% lethal concentrations, LC 10 and LC 30 ) was investigated on developmental and reproduction parameters of the tomato leafminer Tuta absoluta. Lethal concentrations were estimated by leaf dip bioassay on the fourth instar larvae of the T. absoluta that, LC 50 , LC 30 and LC 10 were 0.23, 0.15 and 0.12 mg · l -1 , respectively. The sublethal concentrations led to significant decreases in adult emergence, the percentage of pupation of the parent generation, fecundity and adult longevity compared to the control. Sublethal concentrations significantly decreased the net reproductive rate (R 0 ), intrinsic rate of increase (r), finite rate of increase (λ), and gross reproduction rate (GRR). There was a significant decrease in the time to egg developmental and doubling time (DT) of T. absoluta. However, sublethal concentrations of abamectin had no significant effects on the percentage of pupation, larva, prepupa and pupa developmental periods, hatchability and sex ratio of offspring. The results of this study indicated that sublethal concentrations of abamectin could influence some biological parameters of T. absoluta. The results could also be helpful for making better management decisions for controlling the tomato leafminer.

http://www.eje.cz Entomopathogenic fungi can be useful tools for controlling insect pests and are usually compatible with other biologically-based tactics in integrated pest management programs (Gurulingappa et al., 2011). One of the most effective entomopathogens against A. gossypii is Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales) (Loureiro & Moino, 2006). This entomopathogen can also colonize plants and proliferate as an endophyte (Klieber & Reineke, 2015; McKinnon et al., 2018). Endophytic fungi occur ubiquitously in plants, often without any adverse effects on them, and may actually improve plant tolerance of abiotic and biotic stresses (Ownley et al., 2008; Mo-

The tomato leaf miner, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is one of the most destructive pest of solanaceae and it prefers tomato (Solanum lycopersicum L.). The aim of the current study was to investigate the effects of a wide range of seed proteinaceous extracts from different plant families against T. absoluta α-amylase activity. The effect of pH on the inhibitory activity of seed extracts showed that seed extracts of amaranth along with a wheat cultivar (Alvand, Aflak, Sarvdasht, Alborz, and Kavir) produced more than a 50% inhibition of the insect amylase. Aflak wheat seed extract at 10 μg, inhibited 81% of the insect amylase. This percent was the highest inhibition achieved. The other proteinaceous seed extracts had a lower effect on the enzymatic activity. Probit analysis showed that Aflak, Kavir, Alborz, Alvand, Sarvdasht, and amaranth inhibited the amylase activity with an I50 of 1.94, 3.24, 3.46, 3.31, 4.97, and 15.39 μg, respectively. The effect of pH on the inhibition of the α-amylase showed the highest inhibition of Amaranth and wheat, at a pH value of 8.0, which corresponds to the pH of the insect’s gut. Gel electrophoresis assays confirmed the spectrophotometric assays showing that the α-amylase of the insect gut was affected by the presence of the seed extracts. In the gel assay, a high concentration (14 μg protein) of amaranth proteinaceous seed extract greatly decreased the intensity of the α-amylase band. A high concentration of the Aflak wheat cultivar (10 μg protein) caused the disappearance of the amylase band in the gel. Thus, it is concluded that the physiochemical environment of the insect gut affects the interaction between digestive α-amylase and the metabolites. The experiments showed that seed proteinaceous extracts from non-host plant species, produced more inhibition of the insect amylase when compared to the host plant species. It appears that with evolution, adaptation took place so that insect/s could overcome the plant metabolites.

The nutritional status of host plants can have direct impacts on herbivore physiology and insect–plant interactions. We investigated the effect of micronutrients, including manganese, iron, zinc, and copper, on cucumber plant physiology, and on the biology and physiology of a strain of Aphis gossypii Glover selected over 12 generations to be resistant to pirimicarb. The micronutrient treatment increased the activity of superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, polyphenol oxidase, and phenylalanine ammonia-lyase in cucumber plants, and also increased levels of total phenolics, hydrogen peroxide, salicylic acid, and total chlorophyl, whereas malondialdehyde levels were unaffected. Pirimicarb-resistant cotton aphids that fed on micronutritient-amended cucumber plants expressed significantly decreased levels of acetylcholinesterase and detoxifying enzymes, specifically glutathione S-transferase, and carboxylesterase. Analysis of energy reserves in resistant A. gossypii fed on micronutritient-amended plants revealed decreases in the lipid and protein contents of aphids, whereas glycogen and carbohydrate contents showed no response. Resistant cotton aphids fed on micronutritient-amended plants showed significantly reduced fecundity, longevity, and reproductive periods, and a 1.7-fold reduction in pirimicarb LC50 compared with those fed on control plants. We conclude that micronutrient amendment negatively impacts the biological performance of insecticide-resistant cotton aphids, and diminishes their resistance to pirimicarb. Both direct effects on plant health, such as enhanced inducible defenses, and indirect effects on aphid fitness, such as reduced biological performance and detoxification abilities, were implicated. Therefore, optimization of micronutrient amendments could be a useful complement to other tactics for managing insecticide-resistant A. gossypii on cucumbers, and warrants exploration in other contexts.

Cacopsylla permixta and Cacopsylla bidens are major pests of pears in Iran. They are commonly sprayed with various insecticides up to 12 times a year but control by these means is no longer reliable, suggesting the evolution of resistance. Here, we report about 60‐fold variation in diazinon susceptibility both among five geographic populations of C. bidens and among three geographic populations of C. permixta, as well as 12‐ to 14‐fold variations in imidacloprid susceptibility in these populations. The levels of resistance to the two compounds were highly correlated in the different populations. Esterase, cytochrome P450, and glutathione S‐transferase activities all varied by about two‐fold among the different populations and were also highly correlated with population resistance to the two insecticides, implying differences in metabolism contribute to the differences in resistance. Bioassays with inhibitors of each class of enzyme indicated all three, but particularly the esterases, contributed to the variation in diazinon resistance, while esterase and, in particular, cytochrome P450 activities contributed to the variation in imidacloprid resistance. The most resistant populations of each species also showed some resistance to chlorpyrifos and acetamiprid, suggesting there may be wide cross resistance to organophosphates and neonicotinoids in these populations. The sampled psyllid populations showed lower levels of resistance to representatives of two other classes of insecticides currently used in Iran, spirotetramat and abamectin, though resistance to spirotetramat was detectable and was correlated with diazinon and imidacloprid resistance across populations. We conclude that metabolic resistance to a range of insecticides is now evolving in field populations of both species in Iran, warranting timely development of resistance management plans.

The elm leaf beetle, Xanthogalerucella luteola (Muller) (Col.: Chrysomelidae) is a serious pest of elm trees and it has been distributed all over the world. The current study was undertaken to investigate the inhibitory effects of protein extracts of three weed seeds including datura Datura stramonium L., amaranth Amaranthus retroflexus L. and wild oat Avena fatua L. against X. luteola α-amylase using spectrophotometric assay as well as in gel assays. The effects of five concentrations of each seed proteinaceous extracts were tested on α-amylase activity of the larval gut. The results showed a dose dependent manner in inhibition of the insect enzyme. At the highest concentration of protein extracts (12 μg protein) of all three seed extracts including amaranth, wild oat and datura, the inhibition was 71, 79 and 31%, respectively. Whilst, at low concentration (0.75 μg protein), the inhibition observed was 15, 36 and 5%, respectively. Thus, the greatest inhibition percentage was obtained when proteinaceous extract of wild oat seed was used. These results were confirmed when in gel assays were performed. All three seed proteinaceous extracts had an optimum pH inhibition of 6.0. Thus, it is concluded that wild oat seed proteins are potentially good for detailed investigation in order to get a clear picture of its active compound/s and its structure-function relationship.