Insect Growth Regulator Insecticides Research Articles

Green synthesis and bioefficacy screening of new insect growth regulators as eco-friendly insecticides against the cotton mealybug Phenacoccus solenopsis.

Overcoming or reducing the majority of difficulties caused by the use of common pesticides requires the use of developed, secure, unique and selective organic compounds. Due to their clear mechanism of action on pests and lower poisonousness towards vertebrates than conventional insecticides, juvenile hormone analogues as an example of insect growth regulators appear promising. Thus, a unique set of pure insect growth regulators has been synthesized. The structure of these synthesized compounds, which were related to the most well-known insect growth regulator insecticides, was confirmed by elemental and contemporary spectroscopic investigations (IR, UV, 1 H-NMR, 13 C NMR, and Dept 135 spectrum). Under laboratory conditions, the effectiveness of a chemically newly synthesized products was tested against the cotton mealybug, Phenacoccus solenopsis, and compared with Fenoxycarb as a reference insecticide. Compound 7 was discovered to be more effective than the other synthetic compounds, with LC50 values of 0.907 mg/L for adult female P. solenopsis and 0.377 mg/L for third instar nymphs. Furthermore, this results concluded that the adult female's stage of P. solenopsis was less sensitive to the checked treatments as matched to the third instar nymphs.

Design and synthesis of novel N, N′-substituted benzamide derivatives as potential insecticidal agents against the white mango scale insect, Aulacaspis tubercularis (Hemiptera: Diaspididae)

The white mango scale insect Aulacaspis tubercularis (Newstead) (Hemiptera: Diaspididae), which causes defoliation, drying out of young twigs, dieback, poor flowering, and decreased fruit output, causes serious damage to mango trees in Egypt. Attacks on mango fruits result in pink imperfections that lower their value as a commercial and export item. The current report aims to support the development of integrated management plans to combat A. tuberculosis and to identify more effective, eco-friendly insecticides. The bug may cause a considerable decrease in mango production and jeopardize the sustainability of mango plantation production if no management measures are taken. Currently, the application of a small number of insecticides—the majority of which have poor performance and are disruptive is the primary method used to manage A. tubercularis. In order to suppress this insect, we created novel pesticides called insect growth regulators (N, N′-substituted benzamide derivatives). By using both traditional and elemental spectroscopic investigations (IR, 1HNMR, and 13CNMR), these synthesized compounds which are linked to the most well-known insect growth regulator insecticides had their structures validated. The findings showed that A. tubercularis nymphs were more responsive to the evaluated treatments than adult females. After one day of application, all tested treatments resulted in a sizable proportion of mortality; the percentage of mortality increased with time for both A. tubercularis nymphs and adult females. Furthermore, the treatment with compound 3b was more effective than other synthesized compounds, with a LC50 of 0.318 ppm against nymphs and a LC50 of 0.993 ppm against adult females of A. tubercularis. While the treatment with compound 5 was the least toxic for controlling this pest, many assessments are essential to studying the efficacy of these treatments on advantageous insects.

Lethal and Sublethal Effects of Cyromazine on the Biology of Musca domestica Based on the Age-Stage, Two-Sex Life Table Theory.

Cyromazine is a triazine insect growth regulator insecticide that is recommended for control of Musca domestica worldwide. Cyromazine is highly effective in causing mortality of M. domestica; however, some aspects of its lethal and sublethal effects on the biology of M. domestica are still unknown. The present study explored lethal and sublethal effects on several biological traits and population parameters of M. domestica. Concentration-response bioassays of cyromazine against third-instar larvae of M. domestica exhibited sublethal and lethal effects from concentrations of 0.03 (LC10), 0.06 (LC25), and 0.14 (LC50) μg/g of a larval medium. Exposure of M. domestica larvae to these concentrations resulted in reduced fecundity, survival, longevity and oviposition period, and delayed development of immature stages (i.e., egg hatch time and larval and pupal durations) in the upcoming generation of M. domestica. The values of population parameters such as intrinsic rate of increase, finite rate of increase, net reproductive rate, age-specific survival rate and fecundity, and age-stage life expectancy and reproductive value, analyzed using the age-stage and two-sex life table theory, were significantly reduced in a concentration-dependent manner in comparison with the control group. In conclusion, the study highlights the significant effects of cyromazine on the biology of M. domestica that could help suppress its population in cases of severe infestations.

Worldwide Status of Insecticide Resistance of Aedes aegypti and Ae. albopictus, Vectors of Arboviruses of Chikungunya, Dengue, Zika and Yellow Fever.

Controlling of Aedes aegypti and Ae. albopictus, vectors of five important mosquito-borne diseases, is known as the most effective method to prevent the transmission of arboviruses to humans, but the emergence of insecticide resistance is threat for control and prevention of vector borne diseases. A better understanding of mosquito resistance to insecticides will help to develop more effective methods to control insecticide resistance in mosquito vectors. Worldwide geographical distribution of insecticide resistance in Ae. aegypti and Ae. albopictus by the available papers and map of the data for carbamates, organochlorines, organophosphates, pyrethroids, microbial and insect growth regulator insecticides were reviewed. Article data published up to December 2022 were investigated by searching the following databases: "Google Scholar", "PubMed", "Scopus", "SID" and "Web of Knowledge". The results showed that the susceptibility and resistance status of Ae. aegypti and Ae. albopictus to insecticides in the world is very diverse. Due to the importance of Ae. aegypti and Ae. albopictus in the transmission of mosquito-borne arboviruses, resistance management should be given more attention worldwide to prevent insecticide resistance in the arbovirus vector and replace the new approach for vector control.

Effect of Insect Growth Regulator Insecticides Novaluron, Teflubenzuron and Lufenuron on the Morphology and Physiology of Euschistus heros

The Neotropical brown stink bug, Euschistus heros (F.) (Heteroptera: Pentatomidae), is an important pest that damages soybean, especially in the central-west region of Brazil. The effect of insect growth regulator insecticides on fourth-instar nymphs and adults of the neotropical brown stink bug was evaluated under laboratory and greenhouse conditions, respectively. In the laboratory, the insecticides (doses in g a.i. ha-1) novaluron (20.0 and 40.0), teflubenzuron (26.2 and 52.5), and lufenuron (20.0 and 40.0), in addition to the control (water), were tested on fourth-instar nymphs of E. heros and their development were followed to adulthood. Mortality, number of adults with and without deformities, and fecundity were determined. In a greenhouse, the effects of the same insecticides on the adult of the stink bug were evaluated by determining the fecundity and viability of the eggs laid. The fourth-instar nymphs of E. heros, when exposed to either dose of the tested insecticides presented mortality and insects with deformations, as well as reduced fecundity of females that reached adulthood. In the trial with adult E. heros, all tested insecticides reduced stink bug fecundity. In the same way, the viability of the produced eggs was reduced in all the chemical treatments, except for novaluron at the lowest dose tested, in which egg viability did not differ from the control treatment. Based on the obtained results, one can infer that the growth-regulator insecticides evaluated, although usually more suitable for the control of caterpillars, can interfere negatively in the development and reproduction of the neotropical brown stink bug, thus constituting a complementary alternative for the management of this pest.

Effects of Tebufenozide on Eggs, Larvae and Adults of Chrysoperla carnea (Neuroptera: Chrysopidae).

Quantifying compatibility among control agents is essential for development of integrated pest management (IPM). Chrysoperla carnea (Siemens) and insect growth regulator insecticides are widely used in IPM of Lepidoptera. C. carnea is a generalist predator naturally present in the Mediterranean agroecosystems and bred in insectariums for commercial purposes. Here, we evaluated lethal and sublethal effects of tebufenozide on C. carnea under laboratory conditions. The treatment of eggs with tebufenozide 24 or 48 h after they were laid did not affect the hatching rate or survival of the neonate larvae. Toxic effects of tebufenozide on topically treated larvae was low; development times of surviving larvae and pupae decreased significantly compared with controls. In choice bioassays, a high percentage of third-instar larvae chose prey (Spodoptera littoralis) treated with tebufenozide in preference to untreated prey. Moreover, second-instar larvae of C. carnea that had previously consumed tebufenozide-treated prey (0.75 mL/L) had significantly reduced larval development time compared with controls, while longevity of surviving adults, fecundity and egg viability were unaffected. Ingestion of tebufenozide by adults of C. carnea at the recommended field dose had no significant effect on female fecundity, egg viability or adult longevity. Tebufenozide exhibited low toxicity towards the developmental stages of C. carnea and is therefore a candidate for inclusion in IPM strategies.

Biological and physiological responses of two Bradysia pests, Bradysia odoriphaga and Bradysia difformis, to Dinotefuran and Lufenuron

Bradysia odoriphaga and Bradysia difformis are destructive root maggots that cause severe losses to vegetables, flowers and edible fungi. Due to the long-term dependence on single pesticides, Bradysia resistance to insecticides has increased, and field control efficacy has decreased obviously. To screen alternative insecticides, and compare the insecticide susceptibility of these two species, we tested the toxicity of eight insecticides to B. odoriphaga and B. difformis, and measured the sublethal effects of Dinotefuran and Lufenuron on life-history parameters and detoxification enzyme activities. Bioassay results indicated that Dinotefuran and Lufenuron had relatively higher toxicity to B. odoriphaga and B. difformis compared to other neonicotinoid and insect growth regulator insecticides, respectively. Significant adverse impacts caused by sublethal concentrations (LC20) of Dinotefuran and Lufenuron on the life-history parameters of F0 and F1 generations of B. odoriphaga and B. difformis were observed. These included reduced survival, prolonged larval development and reduced adult longevity and fecundity. B. odoriphaga had greater resistance and adaptation to insecticides than B. difformis, and an LC20 concentration of Dinotefuran stimulated the reproduction of B. odoriphaga F1 generation and increased the life table parameters. Detoxifying enzymes (CarE and GSTs) and P450 activities fluctuated after a sublethal concentration (Dinotefuran and Lufenuron) treatment, and at the peak value of enzyme activities, the enhancement of detoxifying enzymes of B. odoriphaga was significantly higher than that of B. difformis. These results indicated that Dinotefuran and Lufenuron should be considered as alternatives to other insecticides for control of root maggots. B. odoriphaga exhibited stronger adaptation to insecticides than B. difformis. These data provide guidance for control of root maggots, and the basic information presented here can help reveal the differences in adaptive mechanisms between B. odoriphaga and B. difformis.

Insecticidal thioureas: Preparation and biochemical impacts of some novel thiobenzamide derivatives as potential eco-friendly insecticidal against the cotton leafworm, Spodoptera littoralis (Boisd.)

The following work could bring new insights into the application of heterocyclic N, N′-substituted thiobenzamide derivatives as novel pesticides. Insect growth regulators such as chitin synthesis inhibitors seem promising because of their specific mode of action on insects and their lower toxicity against vertebrates than conventional insecticides. Thus, a novel series of thiobenzamide derivatives have been prepared in a pure state. The structure of these synthesized compounds which related to the most famous insect growth regulator insecticides, were confirmed by elemental and modern spectroscopic analyses (IR, UV, 1HNMR and 13CNMR). Toxicological and biochemical parameters of the synthesized compounds against the cotton leafworm, Spodoptera littoralis under laboratory conditions were also investigated. Regarding the determined LC50 value for compound 2,4-Dichloro-N-[(2-methoxyphenyl)carbamothioyl]- benzamide 14 showed the most potent toxic effects than the other synthetic target compounds, with LC50 46.84 ppm of 2nd instar larvae and LC50 148.05of the 4th instar larvae.

Toxicity assessment of two IGR insecticides on eggs and larvae of the ladybird Eriopis connexa.

Eriopis connexa is an important predator in the Neotropical region, associated with pests of economic relevance on horticultural crops in Argentina. The use of broad-spectrum insecticides could reduce the biodiversity of these natural enemies in agroecosystems and put at risk its conservation. New, selective "risk reduced" insecticides could be an alternative to conventional chemical control to promote sustainable agriculture. The goal of this work was to assess the lethal and sublethal effects of two insect growth regulator (IGR) insecticides on eggs and two larval instars of E.connexa exposed to insecticides. Pyriproxyfen and cypermethrin significantly affected egg hatching by 28.8% and 70.4%, respectively. Pyriproxyfen reduced the survival of larvae that emerged by ≈52% from Day (D3)3 after hatching and caused the lengthening of developmental time for both larval and pupal stages. By contrast, teflubenzuron did not reduce hatching and survival but shortened the developmental time of the pupae stage. Cypermethrin reduced the survival of 2nd (L2 ) and 4th (L4 ) larval instars by 36.4% and 74.6%, respectively, and lengthened the development time of L2 . Pyriproxyfen lengthened the development time of L4 and reduced the fecundity and fertility of females. Teflubenzuron reduced survival of L2 and L4 larval instars by 46.9% and 28.6%, respectively, and lengthened the total development time for the larval stage. In addition, teflubenzuron reduced the fecundity and fertility of females. Both eggs and larvae were susceptible to exposure to IGR, showing lethal and sublethal effects. This study highlights, once again, the higher toxicity of cypermethrin to E.connexa. The toxicity of both IGR insecticides could impair the performance of E.connexa as a biological control agent in agroecosystems. © 2022 Society of Chemical Industry.

Insecticide Resistance in the West Nile Encephalitis, Japanese Encephalitis, Avian Malaria and Lymphatic Elephantiasis Vector, Culex pipiens complex (Diptera: Culicidae) in Iran.

Culex pipiens complex is considered as a vector of some important diseases such as West Nile fever, equine encephalitis, Rift valley fever, St. Louis encephalitis, Elephanthiasis and avian malaria in the world. The main measure for vector control is using insecticides. High use of insecticides caused resistance in the populations. The aim of this study was to review the status of insecticide resistance in the vector. Insecticide resistance in this species was found by the available papers and map of the data for carbamates, organochlorine, organophosphates, pyrethroids, microbial and insect growth regulator insecticides were done. An intensive search of scientific literature was done in "PubMed", "Web of Knowledge", "Scopus", "Google Scholar", "SID", and related resources. Results showed that a wide variety of resistance to different insecticides in the country. Due to importance of this species in transmission of diseases. resistance management strategies should be further considered to prevent from in secticide resistance and replacement of novel approach for vector control.

Susceptibility of Cydalima perspectalis (Lepidoptera: Crambidae) larvae to some reduced-risk insecticides in laboratory bioassays

Box tree moth (BTM) Cydalima perspectalis (Walker, 1859) is the most harmful pest of different boxwood species in Europe and Asia including Caspian boxwood Buxus hyrcana in the Hyrcanian forests of Iran. Accessible and effective eco-friendly insecticides are required for the pest control. Thus, susceptibility of 2<sup>nd</sup> and 4<sup>th</sup> instar larvae of BTM to commercial formulation of Bacillus thuringiensis (Bt), two plant extract formulations, Bio1<sup>®</sup> and Matrine<sup>®</sup>, and three insect growth regulator (IGR) insecticides, chlorfluazuron, chromafenozide and diflubenzuron were investigated in laboratory bioassay. Except for diflubenzuron, significant mortality of both instar larvae was observed. At the endpoint of the experiments (96 h), 75.2–90% of second and 80–85% of fourth instar larvae had already died, as a result of feeding on leaves treated with the highest concentration of the insecticides. Furthermore, based on Probit analysis, Matrine<sup>®</sup> exhibited the highest efficiency (lethal concentration LC<sub>50</sub> = 2.87 μL·L<sup>–1</sup>) on 2<sup>nd</sup> instar larvae and followed by Bio1<sup>®</sup> (8.07 μL·L<sup>–1</sup>), chlorfluazuron (173.3 μL·L<sup>–1</sup>) and Bt (326.3 mg·L<sup>–1</sup>). The LC<sub>50</sub> of Matrine<sup>®</sup> and Bt for 4<sup>th</sup> instar larvae were 1.75 μL·L<sup>–1</sup> and 335.8 mg·L<sup>–1</sup>, respectively. Our study revealed that Matrine<sup>®</sup> and chromafenozide could be alternatively used against BTM in situations where there is a permission and need to use insecticides.

Technology for Rapid Detection of Cyromazine Residues in Fruits and Vegetables: Molecularly Imprinted Electrochemical Sensors.

Cyromazine is an insect growth regulator insecticide with high selectivity and is widely used in the production and cultivation of fruits and vegetables. In recent years, incidents of excessive cyromazine residues in food have occurred frequently, and it is urgent to establish an accurate, fast, and convenient method for the detection of cyromazine residues to ensure the safety of edible agricultural products. To achieve rapid detection of cyromazine residues, we prepared a molecularly imprinted electrochemical sensor for the detection of cyromazine residues in agricultural products. Samples of tomato (Lycopersicon esculentum Miller), cowpea (Vigna unguiculata), and water were tested for the recovery rate of cyromazine. The results showed that the concentration of cyromazine showed a good linear relationship with the peak response current of the sensor developed in this study. The lower limit of detection for cyromazine was 0.5 µmol/L, and the sensor also had good reproducibility and interference resistance. This paper can be used as a basis for the study of methods for the detection of cyromazine residues in edible agricultural products.

Evaluation of triflumuron and pyriproxyfen as alternative candidates to control house fly, Musca domestica L. (Diptera: Muscidae), in Riyadh city, Saudi Arabia.

This study was conducted to determine the susceptibility and resistance of some house fly strains of Musca domestica L. to the insect growth regulator insecticides triflumuron and pyriproxyfen in some locations in Riyadh city. Field-collected strains of M. domestica L. from five sites in Riyadh city that represented five slaughterhouse sites where flies spread significantly were tested against triflumuron and pyriproxyfen. Triflumuron LC50 values for the five collected strains ranged from 2.6 to 5.5 ppm, and the resistance factors (RFs) ranged from 13-fold to 27-fold that of the susceptible laboratory strain. Pyriproxyfen LC50 values for the field strains ranged from 0.9 to 1.8 ppm with RFs of 3-fold to 5-fold. These results indicate that pyriproxyfen is an effective insecticide to control house flies and should be used in rotation with other insecticides in the control programs applied by Riyadh municipality.

Posttreatment temperature influences toxicity of insect growth regulators in Musca domestica.

Musca domestica is one of the major cosmopolitan pests in livestock facilities because it can be both a nuisance and a vector of pathogens to animals. Currently, treatment of animal manure with insect growth regulator (IGR) insecticides is among major practices to control M. domestica throughout the year over wide-ranging environmental temperatures. Fluctuation in daily or seasonal temperature is one of the most established factors impacting toxicity of insecticides against insect pests. In this study, the effect of posttreatment temperature (range, 20-36 °C) on the toxicity of eight IGRs: five chitin synthesis inhibitors (cyromazine, diflubenzuron, lufenuron, novaluron, triflumuron), two juvenile hormone analogs (methoprene, pyriproxyfen), and one ecdysone agonist (methoxyfenozide), was investigated against M. domestica. The toxicity of lufenuron and novaluron increased by 1.78 times over the range of 20-28 °C, and 2.25 and 1.83 times, respectively, over the range of 28-36 °C, with an overall increase by 4.00 and 3.26 times, respectively (i.e., positive temperature coefficient). In contrast, the toxicity of diflubenzuron, pyriproxyfen, and triflumuron decreased by 1.43, 1.89, and 2.10 times, respectively, over the range of 20-28 °C, and 1.70, 2.00, and 1.95 times, respectively, over the range of 28-36 °C, with an overall decrease by 2.43, 3.78, and 4.10 times, respectively. The toxicity of cyromazine, methoprene, and methoxyfenozide did not change significantly. Overall, these data will help stakeholders to choose appropriate insecticides for M. domestica control depending on the prevailing environmental temperature and to avoid misuse of insecticides that ultimately lead to environmental safety.

Macadamia felted coccid impact on macadamia nut yield in the absence of a specialized natural enemy, and economic injury levels

Macadamia nut is among the most important edible crops produced in Hawaii. Macadamia also accounts a significant amount of agricultural land in the state at about 6920 ha of active production. Currently, macadamia has one major insect pest that requires considerably more severe management than others; the macadamia felted coccid, Acanthococcus (previously Eriococcus) ironsidei. Horticultural oils and insect growth regulator insecticides are frequently used to control this pest, without any knowledge of economic injury level currently. This study quantified yield loss and impact on nut quality related to A. ironsidei in Hawaii, on two varieties in two different environments, one mesic, and the other dry. Based on these data, EIL estimates were developed for A. ironsidei on macadamia. There was significant variation in yield loss to A. ironsidei in the two varieties and locations. Some varieties of macadamia nut had severe yield losses under dry-habitat conditions, while others tolerated higher A. ironsidei infestations better, with a lower rate of yield loss. Kernel quality was largely not impacted by A. ironsidei infestation, and reduction in yield was the only impact detected. There were correspondingly variable EILs estimates from the different varieties and environments. The implications of high yield loss in a crop in the absence of a natural enemy of the primary pest are discussed. Results of this study will help to contribute to developing an effective integrated pest management program for A. ironsidei management in Hawaii.

Triflumuron induces cytotoxic effects on hepatic and renal human cell lines.

Insect growth regulator insecticides are a new class of pesticides, commonly used around the world to control insect damages. Among those compounds, we focused our interest on triflumuron (TFM), which is less toxic than other conventional insecticides. However, not much is known about its toxic effects on mammalian systems. Therefore, our study aimed toward evaluating the cytotoxic and genotoxic effects of TFM using two different cell lines, the human renal embryonic cells (HEK 293) and hepatocytes (Hep G2). We showed, according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, that TFM reduced significantly the cell viability and increased the reactive oxygen species generation, malondialdehyde levels, and mitochondrial membrane potential in both cell lines. The antioxidant system was disturbed as assessed by the increased activities in both catalase and superoxide dismutase. We demonstrated also, that TFM is an inductor of DNA damages quantified by the comet assay. Moreover, we showed an overexpression of proapoptotic Bax and a decrease in antiapoptotic Bcl-2 expression. As a conclusion, we demonstrate that the liver presents the major target organ to TFM, in which the cytotoxicity and the genotoxic effects were significantly higher in hepatic cells than in renal cells and by consequence its uses must be controlled.

Evaluación de la eficacia de novaluron 0,2 % GR para el control de Aedes (Stegomyia) aegypti (Diptera)

Aedes (Stegomyia) aegypti es el vector principal de dengue, zika y chikungunya en las Américas, enfermedades de gran impacto en salud pública. De acuerdo con la Organización Mundial de la Salud (OMS), el control de estas enfermedades requiere un enfoque integral, y el control larvario hace parte de tal estrategia. Con base en ello, los Insecticidas Reguladores de Crecimiento (IRC) surgen como una alternativa eficiente para el control de los estados inmaduros de este mosquito. Con el propósito de evaluar la eficacia del IRC novaluron 0,2 % GR se determinaron en laboratorio las concentraciones letales (CL) 50, 90, 95 y 99 sobre larvas de cuarto estadio de Ae. aegypti , y en condiciones de campo se estimó el porcentaje de inhibición de emergencia empleando las CL obtenidas en laboratorio, mediante dos esquemas de manejo de agua, con recambio y sin recambio, en recipientes de 40 L, en 30 viviendas en un barrio de Medellín (Antioquia, Colombia) con alta incidencia de dengue. Los bioensayos indicaron que las CL 50, 90, 95 y 99 correspondieron a 0,019; 0,055; 0,065 y 0,084 mg/L, respectivamente. Los resultados de campo revelan que novaluron 0,2 % GR inhibió eficientemente la emergencia de adultos de Ae. aegypti indicando el potencial del producto como regulador de poblaciones a muy bajas concentraciones. Se considera que el producto es de gran utilidad en los programas de prevención y control de dengue, zika y chikungunya.

Mass‐trapping trials for the control of pine processionary moth in a pine woodland recreational area

AbstractThe pine processionary moth, Thaumetopoea pityocampa, causes serious defoliation to Cedrus, Pinus and Pseudotsuga trees, as well as health problems in humans, pets and farm animals due to their urticating hairs. Environmentally friendly strategies for the management of T. pityocampa include: removal of egg batches, removal of nests, trapping of migrant larvae, spraying microbial or Insect Growth Regulator (IGR) insecticides and biocontrol, as well as pheromone‐based adult trapping and mating‐disruption. In the present paper, results on innovative technology for the control of T. pityocampa infestation using pheromone mass‐trapping are reported. Two 1‐ha plots were identified in the study area (central‐south Italy), a pine woodland recreational site growing Pinus halepensis. In the experimental plot (MT‐plot), 10 G‐traps (funnel trap type) baited with (Z)‐13‐hexadecen‐11‐ynyl acetate sex pheromone component were placed for mass‐trapping of adults; the other plot was used as a control‐plot (C‐plot). The T. pityocampa population was monitored using the two central traps in the MT‐plot and two traps positioned in the C‐plot. In addition, the winter nests made by T. pityocampa larvae overwintering on pine trees were counted. After 2 years of mass‐trapping, the number of adults trapped by the monitoring pheromone traps decreased in the MT‐plot, but not in the C‐plot, whereas the number of nests decreased in both plots. Statistical results highlighted significant differences in trap catches between the two plots but not between years. In the case of nests, differences among plots were not significant before the mass‐trapping, but significant after 1‐year treatment. According to our results, the mass‐trapping technique is able to reduce T. pityocampa infestations. This pheromone method can be applied in combination with other control systems in the context of integrated pest management in recreational areas.

Effects of insect growth-regulator insecticides on the immature stages of Harmonia axyridis (Coleoptera: Coccinellidae)

Harmonia axyridis is an important biological control predator in greenhouses and agricultural fields, and it plays a significant role in the integrated pest management (IPM) of several arthropod pests. We studied the effects of eight insect growth-regulator insecticides (IGRs) on immature stages of H. axyridis by residual toxicity (eggs and pupae) and contact toxicity (larvae) to evaluate the risk of using these IGRs in IPM systems. Diflubenzuron, hexaflumuron and lufenuron caused more than 80% mortality to H. axyridis eggs, larvae and pupae, respectively. Pyriproxyfen was also highly harmful to larvae and pupae of H. axyridis. In contrast, methoxyfenozide and buprofezin caused little mortality and were classified as slightly harmful to immature stages based on a reduction coefficient. In addition to mortality and developmental time, the fecundity, fertility and deformed eggs of offspring were affected, when the predators were exposed to IGRs. Benzoylphenylurea insecticides significantly reduced H. axyridis female fecundity and fertility and increased the number of deformed eggs. The adverse effects are closely connected with the developmental stages of the predators and types and methods of insecticides exposed. All IGRs affected, to some extent, the life-table parameters of H. axyridis when the insecticides applied on immature stages at the highest field rates. Tebufenozide, diflubenzuron, hexaflumuron and lufenuron significantly reduced the Ro, T, r and λ of beetles exposed to the insecticides. The results indicate that IGRs could disturb the population growth and biocontrol activities of H. axyridis when applied at the highest field label rates. Additional studies should be conducted to assess the effects of IGRs on H. axyridis under field conditions before incorporating them in IPM strategies.

Fenoxycarb exposure disrupted the reproductive success of the amphipod Gammarus fossarum with limited effects on the lipid profile.

Insect growth regulator insecticides mimic the action of hormones on the growth and development of insect pests. However, they can affect the development of non-target arthropods. In the present study, we tested the effects of the growth regulator insecticide fenoxycarb on several endpoints in the freshwater crustacean Gammarus fossarum (Amphipoda). Females carrying embryos in their open brood pouch were exposed to 50 μg L-1 fenoxycarb throughout the entire oogenesis (i.e. 21 days). After exposure, newborn individuals from exposed embryos were removed from the maternal open brood pouch for lipidomic analysis, while males were added to assess the reproductive success. After fertilization, the lipid profile, energy reserve content (lipids, proteins and glycogen), and activity of phenoloxidase − an enzyme involved in the immune response − were measured in females. No significant effect of fenoxycarb exposure was observed on the lipid profile of both newborn individuals and females, while reproductive success was severely impaired in exposed females. Particularly, precopulatory behavior was significantly reduced and fertilized eggs were unviable. This study highlighted the deleterious effects of the insect growth regulator fenoxycarb on gammarid reproduction, which could have severe repercussions on population dynamics.