Greenhouse Insect Research Articles

An evaluation of the growth, development, reproductive characteristics and pest control potential of three Trichogramma species on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae).

Tuta absoluta is an invasive alien species that has caused major losses in the Chinese tomato industry. Investigating the growth, development, reproduction and pest control effects of three native species of Trichogramma species on the eggs of T. absoluta could provide an ecological tool for preventing and controlling T. absoluta in China. In this study, we constructed age-stage two-sex life tables for three common species of Trichogramma and determined their relative abilities to control T. absoluta in greenhouse insect cages, thus allowing us to identify the species with the most effective ability to prey on T. absoluta eggs. Analysis showed that the net reproductive rate (R0), gross reproduction rate (GRR) and intrinsic rate of increase (r) of Trichogramma ostriniae were the highest of the three species at 22.85, 32.58 and 1.31, respectively. In the presence of 10 eggs and under ideal conditions, T. ostriniae, Trichogramma chilonis, and Trichogramma dendrolimi produced 9451.04, 5199.56, and 1902.95 offspring, respectively. Following the release of T. ostriniae, tomato leaves incurred a damage index of 1 after the first week, while the number of T. absoluta reduced to 24.60 individuals by week 10 (8.75% of the control treatment). Of the three species of Trichogramma tested in this study, T. ostriniae exhibited the best growth, development, reproductive capacity and predatory ability against T. absoluta, and has broad application prospects. © 2024 Society of Chemical Industry.

The Determination Mealybug Species and Natural Enemies in Pitaya Greenhouses in the Mediterranean Region

Pitaya, Hylocereus spp. (Caryophyllales: Cactaceae) has been one of the new species cultivated in Türkiye in recent years. There are many limiting factors, including pests, diseases and weeds, to decrease the yield and fruit quality in pitaya (dragon fruit) areas in Türkiye. In addition, the pests of pitaya is not fully studied therefore this research has been conducted to determine mealybug species in pitaya greenhouses in Türkiye. The present study aimed to determine mealybug species and its natural enemies (parasitoids, and predator insects) in pitaya greenhouses in Adana, Mersin, and Antalya between 2021 and 2022. According to results of this study, 2 different mealybug species was determined; Phenacoccus solenopsis Tinsley 1898, Phenacoccus madeirensis Green, 1923 (Hemiptera: Pseudococcidae) in pitaya greenhouses. Moreover one parasitoid (Aenasius arizonensis Girault (Hymenoptera: Encyrtidae), and two different predatory insects from 2 different orders and 2 different families (Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), Nephus includens Kirsch (Coleoptera: Coccinellidae) were detected within this research. These two invasive mealybug species have wide spectrum host plants and may cause economically important damages to pitaya, if natural enemies cannot work successfully or control strategies do not applied properly in pitaya greenhouses.

Toxicity and Lethal Effect of Greenhouse Insecticides on Coccinella septempunctata (Coleoptera: Coccinellidae) as Biological Control Agent of Myzus persicae (Hemiptera: Aphididae).

Deltamethrin and imidacloprid are commonly used insecticides for controlling sub-sucking insects in greenhouses. However, their application may cause sublethal effects on the aphid coccinellid predator Coccinella septempunctata (Coleoptera: Coccinellidae). Here, we study (i) the toxicity and the effect of two sublethal doses (LD10 and LD30) of deltamethrin and imidacloprid on C. septempunctata in a laboratory microcosm and (ii) the residual toxicity of the two insecticides in a greenhouse. The results showed that both insecticides reduced fecundity, longevity, the intrinsic rate of increase, the finite rate of increase and the net reproductive rate. However, the developmental time of the fourth instar larvae was prolonged by both insecticides at LD10 and LD30. Deltamethrin residues were toxic 21 DAT (days after treatment) to C. septempunctata fourth instar larvae. In contrast, imidacloprid began in the slightly harmful category (75%) 1 DAT and declined to the harmless category (18.33%) 21 DAT. These results indicate that deltamethrin and imidacloprid have potential risks to C. septempunctata. This study provides information to guide the development of integrated pest management (IPM) strategies in greenhouses.

Isolation of a highly virulent Metarhizium strain targeting the tea pest, Ectropis obliqua.

Tea is one of the most widely consumed beverages around the world. Larvae of the moth, Ectropis obliqua Prout (Geometridae, Lepidoptera), are one of the most destructive insect pests of tea in China. E. obliqua is a polyphagus insect that is of increasing concern due to the development of populations resistant to certain chemical insecticides. Microbial biological control agents offer an environmentally friendly and effective means for insect control that can be compatible with "green" and organic farming practices. To identify novel E. obliqua biological control agents, soil and inset cadaver samples were collected from tea growing regions in the Fujian province, China. Isolates were analyzed morphologically and via molecular characterization to identity them at the species level. Laboratory and greenhouse insect bioassays were used to determine the effectiveness of the isolates for E. obliqua control. Eleven isolates corresponding to ten different species of Metarhizium were identified according to morphological and molecular analyses from soil and/or insect cadavers found on tea plants and/or in the surrounding soil sampled from eight different regions within the Fujian province, China. Four species of Metarhizium including M. clavatum, M. indigoticum, M. pemphigi, and M. phasmatodeae were documented for the first time in China, and the other species were identified as M. anisopliae, M. brunneum, M. lepidiotae, M. majus, M. pinghaense, and M. robertsii. Insect bioassays of the eleven isolates of Metarhizium revealed significant variation in the efficacy of each isolate to infect and kill E. obliqua. Metarhizium pingshaense (MaFZ-13) showed the highest virulence reaching a host target mortality rate of 93% in laboratory bioassays. The median lethal concentration (LC50) and median lethal time (LT50) values of M. pingshaense MaFZ-13 were 9.6 × 104 conidia/mL and 4.8 days, respectively. Greenhouse experiments and a time-dose-mortality (TDM) models were used to further evaluate and confirm the fungal pathogenic potential of M. pingshaense MaFZ-13 against E. obliqua larvae. Isolation of indigenous microbial biological control agents targeting specific pests is an effective approach for collecting resources that can be exploited for pest control with lowered obstacles to approval and commercialization. Our data show the presence of four different previously unreported Metarhizium species in China. Bioassays of the eleven different Metarhizium strains isolated revealed that each could infect and kill E. obliqua to different degrees with the newly isolated M. pingshaense MaFZ-13 strain representing a particularly highly virulent isolate potentially applicable for the control of E. obliqua larvae.

Target-Size-Dependent Application of Electrostatic Techniques for Pest Management in Greenhouses

Two new electrostatic devices were developed to manage greenhouse insect pests. One was an electrostatic insect catcher (EIC) to trap small flying pests, and the other was an arc-discharge zapper (ADZ) to kill larger insects emerging from soil beds. The EIC consisted of negatively charged insulated conductor plates (NIPs) and grounded conductor plates (GCPs), which were alternately arrayed in parallel at defined intervals. The ADZ had the same framework as the EIC, except that the NIPs were replaced with negatively charged non-insulated iron plates (NNPs). The EIC formed a non-discharging electric field between the NIP and GCP to create an attractive force to capture insects. By contrast, the ADZ formed a discharge-generating electric field between the NNP and GCP that killed insects. The EIC was effectively applied to small pests, such as whiteflies, thrips, leaf miners, winged aphids, and shore flies, that can pass through the conventional insect-proof nets installed on greenhouse windows. The ADZ was effective for adult houseflies emerging from pupae in soil beds. Our electrostatic devices are useful for controlling insect pests of different sizes.

BeeDNA: Microfluidic environmental DNA metabarcoding as a tool for connecting plant and pollinator communities

AbstractPollinators are declining globally, and this loss can reduce plant reproduction, erode critical ecosystem services and resilience, and drive economic losses. Monitoring pollinator biodiversity trends is essential for adaptive conservation and management, but conventional surveys are often costly, time‐consuming, and requires considerable taxonomic expertise. Environmental DNA (eDNA) metabarcoding surveys are booming due to their rapidity, nondestructiveness, and cost efficiency. Microfluidic technology allows multiple primer sets from different markers to be used in eDNA metabarcoding for more comprehensive inventories, minimizing associated primer bias. We evaluated microfluidic eDNA metabarcoding for pollinator community monitoring in both controlled greenhouse and natural field settings. Using a variety of sampling, preservation, and extraction methods, we assessed pollinator communities with a number of markers using microfluidic metabarcoding. In greenhouse experiments, microfluidic eDNA metabarcoding detected the target bumblebee in two of four focal flower species as well as greenhouse insects in all focal flower species. In the field, numerous common regional arthropods, including some directly observed, were detected. Pollinator detection was maximized using whole flower heads preserved in ATL buffer and extracted with a modified Qiagen® DNeasy protocol for amplification with COI primers. eDNA surveillance could enhance pollinator assessment by detecting protected and endangered species and being more applicable to remote, inaccessible locations, whilst reducing survey time, effort, and expense. Microfluidic eDNA metabarcoding requires optimization to address remaining efficacy concerns, but this approach shows potential in revealing complex networks underpinning critical ecosystem functions and services, enabling more accurate assessments of ecosystem resilience.

Sex-based de novo transcriptome assemblies of the parasitoid wasp Encarsia suzannae, a host of the manipulative heritable symbiont Cardinium hertigii.

Parasitoid wasps in the genus Encarsia are commonly used as biological pest control agents of whiteflies and armored scale insects in greenhouses or the field. They are also hosts of the bacterial endosymbiont Cardinium hertigii, which can cause reproductive manipulation phenotypes, including parthenogenesis, feminization, and cytoplasmic incompatibility (the last is mainly studied in Encarsia suzannae). Despite their biological and economic importance, there are no published Encarsia genomes and only one public transcriptome. Here, we applied a mapping-and-removal approach to eliminate known contaminants from previously-obtained Illumina sequencing data. We generated de novo transcriptome assemblies for both female and male E.suzannae which contain 45,986 and 54,762 final coding sequences, respectively. Benchmarking Single-Copy Orthologs results indicate both assemblies are highly complete. Preliminary analyses revealed the presence of homologs of sex-determination genes characterized in other insects and putative venom proteins. Our male and female transcriptomes will be valuable tools to better understand the biology of Encarsia and their evolutionary relatives, particularly in studies involving insects of only one sex.

Towards intelligent and integrated pest management through an AIoT-based monitoring system.

Main bottleneck in facilitating integrated pest management (IPM) is the unavailability of reliable and immediate crop damage data. Without sufficient insect pest and plant disease information, farm managers are unable to make proper decisions to prevent crop damage. This work aims to present how an integrated system was able to drive farm managers towards sustainable and data-driven IPM. A system called Intelligent and Integrated Pest and Disease Management (I2 PDM) system was developed. Edge computing devices were developed to automatically detect and recognize major greenhouse insect pests such as thrips (Frankliniella intonsa, Thrips hawaiiensis, and Thrips tabaci), and whiteflies (Bemisia argentifolii and Trialeurodes vaporariorum), to name a few, and measure environmental conditions including temperature, humidity, and light intensity, and send data to a remote server. The system has been installed in greenhouses producing tomatoes and orchids for gathering long-term spatiotemporal insect pest count and environmental data, for as long as 1368 days. The findings demonstrated that the proposed system supported the farm managers in performing IPM-related tasks. Significant yearly reductions in insect pest count as high as 50.7% were observed on the farms. It was concluded that novel and efficient strategies can be achieved by using an intelligent IPM system, opening IPM to potential benefits that cannot be easily realized with a traditional IPM program. This is the first work that reports the development of an intelligent strategic model for IPM based on actual automatically collected long-term data. The work presented herein can help in encouraging farm managers, researchers, experts, and industries to work together in implementing sustainable and data-driven IPM. © 2022 Society of Chemical Industry.

Effect of nitrogen source on mycelial growth, blastospore production and thermotolerance of Cordyceps fumosorosea (Hypocreales: Cordycipitaceae)

Among the entomogenous fungi, Cordyceps fumosorosea has great potential for the control of piercing-sucking insects in greenhouses. The blastospores of C. fumosorosea developed in liquid fermentation are more efficient for industrialization because they can kill insects faster and be produced faster than conidia from solid cultivation. Thermotolerance of blastospores plays a major role in their application in greenhouses. The added nutrient elements during its cultivation process have a significant impact on the thermotolerance of blastospores. Understanding the effects of nitrogen sources on the mycelial growth, sporulation and thermotolerance of C. fumosorosea is essential for its commercial application. Frequently used nitrogen sources were investigated in fermentation medium, including peptone, soya peptone, yeast extract, ammonium sulfate, urea and so on. Soya peptone provided the maximum blastospore yield and GT50, which were 5.17 × 108 blastospores mL−1 and 1.91 h, respectively. To explore the difference in intracellular substances involved in the thermotolerance of blastospores in the presence of different nitrogen sources, intracellular trehalose and mannitol were extracted and then qualified by ion chromatography. The results showed that blastospores with better thermotolerance generally had lower intracellular trehalose content, indicating that the intracellular trehalose content of blastospores could be a factor that the fungus responds to thermal stress and that its content in the blastospores could be adjusted by the supplemented nitrogen source.

High Prevalence of Sensitization to Mites and Insects in Greenhouses Using Biologic Pest Control

Mites and insects are widely used as biologic pest control in greenhouses. A few studies have reported sensitization to mites among greenhouse workers, but the prevalence of sensitization to pest control insects is not known. We aimed to determine the prevalence of IgE-mediated sensitization to pests and their control organisms in the population of exposed greenhouse workers and the relationship between sensitization and allergic symptoms. In a cross-sectional study, we interviewed 117 tomato and cucumber greenhouse workers from eight companies that use biologic pest control. Sensitization to nine organisms was assessed by serum-specific IgE measurement. We also measured fractional exhaled nitric oxide. The prevalence of specific sensitization to pests and pest control organisms was 50%; to mites, 29%; and to insects, 46%. Of the individual species, Macrolophus pygmaeus insect sensitization had the highest prevalence (46%). Asthma symptoms were significantly associated with sensitization to pest and pest control organisms (odds ratio [OR]= 3.9; 95% confidence interval [CI], 1.2-12.5) and with a fractional exhaled nitric oxide level of 25 ppb or greater (OR= 4.8; 95% CI, 1.7-13.8), indicating eosinophilic airway inflammation. Southeast Asian origin was significantly associated with sensitization (OR= 5.1; 95% CI, 2.1-12.1) and rhinitis (OR= 2.8; 95% CI, 1.2-6.3). Tomato and cucumber greenhouse workers were commonly sensitized to predatory insect M pygmaeus and pest control mites. Our findings stress the importance of surveilling and preventing work-related allergic diseases among greenhouse workers.

Evaluation of the compatibility of Isaria fumosorosea (Hypocreales: Cordycipitaceae) IF-1106 with several adjuvants

ABSTRACT The compatibility of Isaria fumosorosea IF-1106 with 12 commercial pesticide adjuvants was evaluated using the predictive parameter SC90 (the adjuvant concentration at which 90% of conidia survived). Based on the SC90 values and the functionalities of the adjuvants used, two conidial wettable powder formulations of IF-1106 were formulated. Our results indicated that SC90 values can be used to evaluate the compatible concentration of adjuvants and Isaria fumosorosea. The wettable powder formulations F1 and F2 formulated on the basis of this research have a conidia germination rate of 92.4% ± 2.5% and 90.6% ± 1.3%, respectively, showing high compatibility, and their main quality control parameters (conidia germination rate, conidia suspension rate, wetting time, etc.) met commercialisation requirements. Our study also verified that IF-1106 is compatible with major surfactant and water-soluble polymer adjuvants in pesticide formulations when the use concentration is less than its SC90. Our research provided a new method for evaluating the compatibility of adjuvants with entomogenous fungi, and formulated two promising mycoinsecticide formulations for sucking insects in greenhouses.

Automatic greenhouse insect pest detection and recognition based on a cascaded deep learning classification method

AbstractInspection of insect sticky paper traps is an essential task for an effective integrated pest management (IPM) programme. However, identification and counting of the insect pests stuck on the traps is a very cumbersome task. Therefore, an efficient approach is needed to alleviate the problem and to provide timely information on insect pests. In this research, an automatic method for the multi‐class recognition of small‐size greenhouse insect pests on sticky paper trap images acquired by wireless imaging devices is proposed. The developed algorithm features a cascaded approach that uses a convolutional neural network (CNN) object detector and CNN image classifiers, separately. The object detector was trained for detecting objects in an image, and a CNN classifier was applied to further filter out non‐insect objects from the detected objects in the first stage. The obtained insect objects were then further classified into flies (Diptera: Drosophilidae), gnats (Diptera: Sciaridae), thrips (Thysanoptera: Thripidae) and whiteflies (Hemiptera: Aleyrodidae), using a multi‐class CNN classifier in the second stage. Advantages of this approach include flexibility in adding more classes to the multi‐class insect classifier and sample control strategies to improve classification performance. The algorithm was developed and tested for images taken by multiple wireless imaging devices installed in several greenhouses under natural and variable lighting environments. Based on the testing results from long‐term experiments in greenhouses, it was found that the algorithm could achieve average F1‐scores of 0.92 and 0.90 and mean counting accuracies of 0.91 and 0.90, as tested on a separate 6‐month image data set and on an image data set from a different greenhouse, respectively. The proposed method in this research resolves important problems for the automated recognition of insect pests and provides instantaneous information of insect pest occurrences in greenhouses, which offers vast potential for developing more efficient IPM strategies in agriculture.

Evaluation of the Toxicity of Satureja intermedia C. A. Mey Essential Oil to Storage and Greenhouse Insect Pests and a Predator Ladybird.

The use of chemical insecticides has had several side-effects, such as environmental contamination, foodborne residues, and human health threats. The utilization of plant-derived essential oils as efficient bio-rational agents has been acknowledged in pest management strategies. In the present study, the fumigant toxicity of essential oil isolated from Satureja intermedia was assessed against cosmopolitan stored-product insect pests: Trogoderma granarium Everts (khapra beetle), Rhyzopertha dominica (Fabricius) (lesser grain borer), Tribolium castaneum (Herbst) (red flour beetle), and Oryzaephilus surinamensis (L.) (saw-toothed grain beetle). The essential oil had significant fumigant toxicity against tested insects, which positively depended on essential oil concentrations and the exposure times. Comparative contact toxicity of S. intermedia essential oil was measured against Aphis nerii Boyer de Fonscolombe (oleander aphid) and its predator Coccinella septempunctata L. (seven-spot ladybird). Adult females of A. nerii were more susceptible to the contact toxicity than the C. septempunctata adults. The dominant compounds in the essential oil of S. intermedia were thymol (48.1%), carvacrol (11.8%), p-cymene (8.1%), and γ-terpinene (8.1%). The high fumigant toxicity against four major stored-product insect pests, the significant aphidicidal effect on A. nerii, and relative safety to the general predator C. septempunctata make terpene-rich S. intermedia essential oil a potential candidate for use as a plant-based alternative to the detrimental synthetic insecticides.

Development of A Combined Insect Trap for Whitefly (bemisia Tabaci) And Tomato Leaf Miner (tuta Absoluta) Management

Whitefly Bemisia tabaci and tomato leaf miner Tuta absoluta are two important insects that are causing serious damage to crops in protected vegetable cultivation. There is an international call from scientists to find a non-chemical way to manage those pests. This study tested the effect of a new combined light trap with different colors, named GLT trap, on the management of whiteflies and tomato leaf miners in protected vegetable cultivation. The results showed that whiteflies are significantly attracted to the yellow light traps (828 insects) compared to (73 insects) on white traps which captured the least number of insects. Although whitefly is diurnal, a higher number of insects were captured by the yellow-light colored traps (910 insects) than both yellow traps without light (302 insects) and light without color (51 insects) in 6 days. This showed the superiority of GLT trap over the yellow traps by about three times and about 20 times more than light traps without colors. In addition, a higher mean number of leaf miners were captured by yellow traps (14.33), and the lowest number of insects (3.5) was captured on violate traps. The new GLT trap is a promising IPM mean to manage those important insects in greenhouses in both developed and developing countries. It is an inexpensive, effective, and homemade way to control whiteflies and tomato leaf miners without negative consequences

Application of an image and environmental sensor network for automated greenhouse insect pest monitoring

Abstract This work presents an automated insect pest counting and environmental condition monitoring system using integrated camera modules and an embedded system as the sensor node in a wireless sensor network. The sensor node can be used to simultaneously acquire images of sticky paper traps and measure temperature, humidity, and light intensity levels in a greenhouse. An image processing algorithm was applied to automatically detect and count insect pests on an insect sticky trap with 93% average temporal detection accuracy compared with manual counting. The integrated monitoring system was implemented with multiple sensor nodes in a greenhouse and experiments were performed to test the system’s performance. Experimental results show that the automatic counting of the monitoring system is comparable with manual counting, and the insect pest count information can be continuously and effectively recorded. Information on insect pest concentrations were further analyzed temporally and spatially with environmental factors. Analyses of experimental data reveal that the normalized hourly increase in the insect pest count appears to be associated with the change in light intensity, temperature, and relative humidity. With the proposed system, laborious manual counting can be circumvented and timely assessment of insect pest and environmental information can be achieved. The system also offers an efficient tool for long-term insect pest behavior observations, as well as for practical applications in integrated pest management (IPM).

Assisted Evolution in Astrobiology-Convergence of Ecology and Evolutionary Biology within the Context of Planetary Colonization.

In ecology and conservation biology, the concept of assisted evolution aims at the optimization of the resilience of organisms and populations to changing environmental conditions. What has hardly been considered so far is that this concept is also relevant for future astrobiological research, since in artificial extraterrestrial habitats (e.g., plants and insects in martian greenhouses) novel environmental conditions will also affect the survival and performance of organisms. The question therefore arises whether and how space-relevant organisms can be artificially adapted to the desired circumstances in advance. Based on several adaptation and acclimatization strategies in wild ecosystems of Earth, I discuss which methods can be considered for assisted evolution in the context of astrobiological research. This includes enhanced selective breeding, induction of epigenetic inheritance, and genetic engineering, as well as possible problems of these applications. This short overview article aims to stimulate an emerging discussion as to whether humans, which are already prominent drivers of Earth's evolution, should consider such interventions for future planetary colonization as well.

Advance in insect phototaxis and the development and application of colored sticky boards

The visual communication between insect and plant is one of the key sensory signal channels for the survival, reproduction and defense of insects. The colored sticky boards, which are developed based on insects positive phototaxis and as one of the effective green pest control measures, have been widely applied for monitoring, forecasting and mass-trapping of many diurnal agricultural and forestry insect pests. In addition, they could be used to attract beneficial insects to the target areas to prey on or parasitize harmful insects, and to aid in pollination. Here, we discussed the insect phototaxis theory and the "attract and kill" mechanism of colored sticky boards and reviewed the effects of color, shape, size, height, density, facing direction, working duration of the sticky boards, as well as plant morphological characters and insect physiological status on trapping efficacy. We summarized various application techniques of the color sticky boards on different target pest insects in tea plantations, vegetable fields and greenhouses, etc. We analyzed various application technologies of combining colored sticky boards with synthetic sex pheromone attractants and/or botanical attractants and their efficacy; then evaluated the pros and cons of using the colored sticky boards for pest control or monitoring. Accordingly, we provided suggestions for improvements and discussed the trapping efficacy assessment and cost-benefit analysis. Finally, we proposed the RD directions of next generation colored sticky boards, especially its combination with synthetic pheromones/kairomones as an important integrated pest management (IPM) measure, and the future of the colored sticky board industry.

A new concept for controlling tiny-scale insect pest in green house – noval technology to apply liquid ethyl formate:

As increased agricultural insecticide uses and trends in insecticide resistance, increased labor cost to apply insecticide and limited its application to fertility season in green house. There is a need of a safe, labor-saving and confined space application concept to manage control tiny-scale insect pest such as thrips and whitefly. Fumigation with ethyl formate (EF), which is considered as effective to various insect pest and safely use in quarantine treatment, was evaluated in the confined space (glass house) and semi-confined space (vinyl house). The new application technology for application of liquid EF could be the one of the key options for control of tiny flying insects in greenhouses that would save labor and operation costs. It could be connected to smartfarm technologies in the near future.

Effects of Growing Medium Type and Moisture Level on Predation by Adult Rove Beetle, Dalotia coriaria (Coleoptera: Staphylinidae), on Fungus Gnat, Bradysia sp. nr. coprophila (Diptera: Sciaridae), Larvae under Laboratory and Greenhouse Conditions

The fungus gnat, Bradysia sp. nr. coprophila (Lintner) (Diptera: Sciaridae), is an insect pest of greenhouse production systems. The rove beetle, Dalotia coriaria [Kraatz] (Coleoptera: Staphylinidae), is a commercially available predator of certain greenhouse insect pests that reside in growing media, including fungus gnats. There is minimal information discussing how growing medium type and moisture level (watering treatment) impact the interactions between pests and natural enemies. Therefore, we conducted laboratory and greenhouse experiments to investigate the influence of two growing media (Sunshine® LC1 Professional Growing Mix and Fafard® 3B Mix Professional Formula) and two moisture levels (“constantly saturated” and “initially saturated”) on predation by adult D. coriaria on B. sp. nr. coprophila larvae after releasing one or two rove beetle adults. In the laboratory experiment, moisture content or the amount of water retained by the growing medium did not significantly influence the recovery of adult fungus gnats for any of the rove beetle treatments. However, there was a significant difference in the recovery of fungus gnat adults between the two growing media. Fewer fungus gnat adults emerged from the Sunshine® LC1 Professional Growing Mix (0.9 ± 0.2 adults) than the Fafard® 3B Mix Professional Formula (6.0 ± 0.9 adults). Significantly fewer adult fungus gnats were recovered in the treatments where one rove beetle adult was released (2.7 ± 0.7 adults) and two rove beetle adults were released (2.3 ± 0.5 adults) compared with the control without rove beetles (5.4 ± 1.4 adults). However, there was no significant difference between the number of rove beetle adults released. In contrast to the laboratory experiment, moisture content in the greenhouse experiment significantly influenced the recovery of adult fungus gnats. More adult fungus gnats were recovered from the “constantly saturated” treatment (9.9 ± 1.4 adults) than the “initially saturated” treatment (3.8 ± 1.0 adults). Similar to the laboratory experiment, there was a significant difference in the recovery of fungus gnat adults between the two growing media, with fewer adults captured from the Sunshine® LC1 Professional Growing Mix (3.2 ± 0.8 adults) than the Fafard® 3B Mix Professional Formula (10.4 ± 1.4 adults). However, the treatments with rove beetle adults [one rove beetle (6.6 ± 1.8 adults) or two rove beetles (5.3 ± 1.5 adults)] were not significantly different from the control without rove beetles (8.6 ± 1.5 adults), suggesting that the growing media and moisture levels were acting directly on fungus gnat survival. The results of our study demonstrate that survival of fungus gnat larvae that reside in the growing medium and the success of rove beetle adults used to regulate these pests can be influenced by growing media and the moisture content within growing media.

Evaluation of the toxicity of fungicides to flight muscle mitochondria of bumblebee (Bombus terrestris L.)

Insects pollinate 75% of crops used for human consumption. Over the last decade, a substantial reduction in the abundance of pollinating insects has been recorded and recognized as a severe matter for food supply security. Many of the important food crops destined for human consumption are grown in greenhouses. A unique feature of greenhouse agriculture is the extensive use of fungicides to curb multiple fungal infections. The most widely used pollinating insects in greenhouses are commercially reared bumblebees. However, there is no data regarding the toxicity of fungicides to bumblebee mitochondria. To fill this gap in knowledge, we examined the effects of 16 widely used fungicides on the energetics of the flight muscles mitochondria of Bombus terrestris. We found that diniconazole and fludioxonil uncoupled the respiration of mitochondria; dithianon and difenoconazole inhibited it. By analyzing the action of these inhibitors on mitochondrial respiration and generation of reactive oxygen species, we concluded that difenoconazole inhibited electron transport at the level of Complex I and glycerol-3-phosphate dehydrogenase. Dithianon strongly inhibited succinate dehydrogenase and glycerol-3-phosphate dehydrogenase. It also strongly inhibited mitochondrial oxidation of NAD-linked substrates or glycerol 3-phosphate, but it had no effect on the enzymatic activity of Complex I. It may be suggested that dithianon inhibits electron transport downstream of Complex I, likely at multiply sites.