Biopesticides Research Articles

Evaluation of the insecticidal efficacy of four plants to protect stored Bambara groundnuts [Vigna subterranea (L.) Verdc. (Fabaceae)

Bambara groundnuts [Vigna subterranean] is one of the main legumes consumed in Northern Cameroon. However, stored nuts by farmers are quickly destroyed by pests leading to low yields. To overcome this constraint, the efficient control of stored grains from insect pests is dependent on synthetic insecticides. To reduce post-harvest losses of stored voandzou seeds, four botanicals insecticides have been developed and evaluated on the main pest. Plant powders prepared from Piper nigrum Linn. (Pipericaceae), Syzygium aromaticum (L.) Merr. & L.M.Perry (Myrtaceae), Xylopia aethiopica Dunal (Annonaceae) and Phaseolus vulgaris L.( Fabaceae), at different doses were tested on Callosobruchus maculatus Fabricius under laboratory conditions. The rest of the study involved combining black bean powder with the three condiment species in different proportions. The analysis shows a highly significant difference (p < 0.0001) between the mortality induced by formulations on day two of exposure with the lowest dose (0.5 g). These mortalities are 100%, 94.44 ± 3.79%, 72.5 ± 96 and 8.33 ± 4.77, respectively for S. aromaticum, P. nigrum, X. aethiopica and P. vulgaris powders. In relation to the formulation, the results show S. aromaticum powder induced 100% mortality compared with 94.44%, 72.59% and 8.33% respectively for P. nigrum, X. aethiopica and P. vulgaris plant powder at a dose of 5%. The results show that the natural substances used had a good insecticidal action against bruchid. The persistent compounds present in the studied spice plant powders are not toxic for human consumption at the concentrations used, but rather a beneficial effect. Key words: botanical insecticide, aromatic plants, powder, seeds, storage, insect pest.

Botanical extracts for insect management: lessons from participatory research in peri-urban horticultural systems of central Argentina

ABSTRACT We evaluate botanical insecticides as a technological device for synthetic input substitution in peri-urban horticultural system transitions. For that purpose, a Participatory Action Research (PAR) framework was proposed, and garlic extracts (GE) performance was evaluated for pest and natural enemy regulation in lettuce crops in conventional and agroecological contexts. Through three PAR cycles under actual production conditions, we observed GE effectiveness on aphids, thrips, and natural enemies. Additionally, context-specific adaptations were noticed: for conventional systems; the extract is useful near harvest and serves as a trust-building tool while reducing synthetic insecticide dependence. Instead, for agroecological systems, garlic extract highlighted biodiversity’s relevance for system redesign.

Multispecies Trichoderma in Combination with Hydrolyzed Lignin Improve Tomato Growth, Yield, and Nutritional Quality of Fruits

The application of biological pesticides as alternatives to chemical phytosanitary products is a natural and innovative method to improve environmental protection and sustainable agricultural production. In this work, the compatibility between Trichoderma spp. and a commercial lignin extract was assessed in vitro and in vivo. The beneficial effects of lignin in combination with different Trichoderma consortia were evaluated in terms of improved growth and quantitative and qualitative tomato productivity. T. virens GV41 + T. asperellum + T. atroviride + lignin formulation was the most effective in growth promotion and increased root and stem dry weight compared to control (45.4 and 43.9%, respectively). This combination determined a 63% increase in tomato yield compared to the control, resulting in the best-performing treatment compared to each individual constituent. Consistent differences in terms of lycopene, GABA, ornithine, total, essential, and branched-chain amino acids were revealed in fruits from tomato plants treated with Trichoderma–lignin formulations (T. asperellum + T. virens GV41 + lignin) or with the microbial consortia (T. asperellum + T. virens GV41, T. atroviride + T. virens GV41). The developed bioformulations represent a sustainable biological strategy to increase yield and produce nutritional compound-enriched vegetables.

Effect of Pipe Materials and Interspecific Interactions on Biofilm Formation and Chlorine Resistance: Turn Enemies into Friends

Drinking water distribution systems (DWDSs) may be contaminated to various degrees when different microorganisms attach to the pipe walls. Understanding the characteristics of biofilms on pipe walls can help prevent and control microbial contamination in DWDSs. The biofilm formation, interspecific interactions, and chlorine resistance of 10 dual-species biofilms in polyethylene (PE) and cast iron (CI) pipes were investigated in this paper. The biofilm biomass (heterotrophic bacterial plate count and crystal violet) of dual species in CI pipes is significantly higher than that in PE pipes, but the biofilm activity in CI pipes is significantly lower than that in PE pipes. The interspecific interaction of Sphingomonas-containing group presented synergistic or neutral relationship in PE pipes, whereas the interspecific interaction of the Acidovorax-containing group showed a competitive relationship in CI pipes. Although interspecific relationships may help bacteria resist chlorine, the chlorine resistance was more reliant on dual-species groups and pipe materials. In CI pipes, the Microbacterium containing biofilm groups showed better chlorine resistance, whereas in PE pipes, most biofilm groups with Bacillus exhibited better chlorine resistance. The biofilm groups with more extracellular polymeric substance (EPS) secretion showed stronger chlorine resistance. The biofilm in the PE pipe is mainly protected by EPS, while both EPS and corrosion products shield the biofilms within CI pipe. These results supported that dual-species biofilms are affected by pipe materials and interspecific interactions and provided some ideas for microbial control in two typical pipe materials.

Integrated pest management farmer field school of Chinese cabbage for young farmers in Batu City

The Abinaya Milenial Youth Farmers Group in Sumber Brantas Village, Bumiaji District, Batu City, faces significant challenges in cultivating Chinese cabbage due to a high incidence of clubroot disease caused by Plasmodiophora brassicae, with infection rates reaching 50–80 percent, leading to crop failure. The overuse of synthetic pesticides has resulted in pathogen resistance. Therefore, we adopted an integrated pest management (IPM) approach focusing on long-term prevention by integrating ecologically-based control techniques. The principles of IPM include managing healthy plants, preserving natural enemies, monitoring, and enhancing farmers' ecological understanding to become IPM experts. Through the IPM Farmer Field School (IPM-FFS), we aimed to implement ecological IPM, improve agroecosystem health, and support sustainable agriculture through participatory extension methods. Activities were conducted from June to November 2023 in Sumber Brantas Village, Bumiaji District, Batu City. The activities included surveys, planning, socialization, teaching, training, and follow-up. The IPM-FFS successfully developed standard operating procedures for Chinese cabbage management, increasing farmers' knowledge of IPM by 85 percent. The adoption of IPM reduced the incidence of clubroot disease to 20 percent, increased production by 420 kg, and reduced production costs by IDR 403,000 on an area of 400 m2. Farmers independently produce compost, compost tea, botanical pesticides, mycorrhizae, and fungicides through the IPM-FFS, empowering them in sustainable agriculture.

Optimization of fermentation conditions for Bacillus velezensis TCS001 and evaluation of its growth promotion and disease prevention effects on strawberries

Bacillus velezensis TCS001 is a novel biocontrol bacterium with broad-spectrum antifungal activity and plant growth-promoting effects, holding great potential for development in agricultural production. This study optimized the fermentation conditions for B. velezensis TCS001 through single-factor experiments combined with response surface methodology, and developed a formulation for TCS001 suspension concentrate (TCS001-SC). The efficacy of TCS001-SC to promote the growth of strawberries and to prevent and control strawberry anthracnose was evaluated. The optimal liquid fermentation condition for TCS001 was determined to be 2.89 % soluble peanut cake powder, 3.0 % glucose, 3.0 % soluble starch, 0.002 % FePO4, 0.006 % KCl, 0.6 % NaCl, 0.05 % MgCl2·6H2O, 0.3 % K2HPO4, 0.15 % KH2PO4, 0.05 % CaCO3, 0.005 % MnSO4, a working volume of 31 % (77.5 mL/250 mL), a rotation speed of 173 r/min, a cultivation temperature of 28°C, an inoculum volume of 1.0 %, and a pH of 7.0. The 15 L fermenter upscale culture achieved a spore count of 9.46 × 109 CFU/mL, which was 2.01 times the spore count of 4.7 × 109 CFU/mL before optimization, and a preliminary TCS001-SC was developed with the fermented broth as the main component. Agar plate confrontation tests showed that TCS001 had antifungal activity against five types of anthracnose fungi, with inhibition rates ranging from 70.3 % to 87.2 %. TCS001-SC could promote the growth of strawberries and induce a rapid defense enzyme response in their leaves, enhancing the plant's resistance to pathogens. After treatment, individual strawberry plants showed significant increases in the number of leaves, fresh weight of stems and leaves, root fresh weight, leaf area, plant height, and the content of POD, SOD, CAT enzymes, GA, IAA, and ABA compared to the control.Additionally, it shows good prevention and control effects against strawberry anthracnose, with a control efficacy of 60.45% after five spray treatments at a concentration of 2 × 107 CFU/mL, which is not significantly different from the efficacy of commercial microbial agents such as Bacillus subtilis wettable powder, subsequent field trials will be conducted to determine its potential as a microbial pesticide. This study provides important support for the future industrial production and application of the strain TCS001.

Making waves: Intelligent phage cocktail design, a pathway to precise microbial control in water systems

Current practices in water and wastewater treatment to control unwanted microbes have led to new problems, including health effects from disinfection byproducts, growth of opportunistic pathogens resistant to residual disinfectants (e.g., chlorine), and antibiotic resistance. These challenges are spurring interest in rethinking our practices of microbial control. Simultaneously, advances in molecular biology and computation power are driving renewed interest in using phages (viruses that infect bacteria) to precisely control microbial growth (aka, phage biocontrol). In this Making Waves article, I begin by reviewing the current state of research into phage cocktail design, emphasizing our limited understanding of the features of successful phage cocktails (combinations of multiple types of phages). I describe the state of modeling phage-bacteria interactions and underscore the need for increasing research efforts to predict phage cocktail success, a key gap slowing the application of phage biocontrol. I also detail how research must also focus on techniques for engineering more effective phages to offer a more rapid alternative to phage discovery from natural environments. In this way, phage cocktails comprised of phages with complementary infection strategies may be designed. The final area for increased research effort that I highlight is the need for phage cocktail design to account for possible unintended environmental effects, a risk that is increasingly acknowledged in phage ecology studies but mostly ignored by those developing phage biocontrol technologies. By focusing more research effort towards the areas necessary for intelligent phage cocktail design, we can accelerate the development of phage-based biocontrol in water systems and improve public health.

Development of a Triplex qPCR Assay Based on the TaqMan Probe for the Detection of Haemophilus parasuis, Streptococcus suis Serotype 2 and Pasteurella multocida

Porcine respiratory disease is a significant economic problem for the global swine industry. Haemophilus parasuis (H. parasuis), Streptococcus suis (S. suis), and Pasteurella multocida (P. multocida) are three important pathogenic bacteria of the swine respiratory tract. Notably, the three pathogens not only frequently manifest as mixed infections, but their striking clinical similarities also present difficulties for pig populations in terms of disease prevention and treatment. Thus, we developed a triplex real-time quantitative polymerase chain reaction (qPCR) assay based on a TaqMan probe for the detection of H. parasuis, S. suis serotype 2, and P. multocida. Primers and probes were designed to target the conserved regions of the H. parasuis OmpP2 gene, the S. suis serotype 2 gdh gene, and the P. multocida Kmt1 gene. By optimizing the reaction system and conditions, a triplex qPCR method for simultaneous detection of H. parasuis, S. suis serotype 2, and P. multocida was successfully established. The amplification efficiencies of the standard curves for all three pathogens were found to be highly similar, with values of 102.105% for H. parasuis, 105.297% for S. suis serotype 2, and 104.829% for P. multocida, and all R2 values achieving 0.999. The specificity analysis results showed that the triplex qPCR method had a strong specificity. The sensitivity test results indicated that the limit of detection can reach 50 copies/μL for all three pathogens. Both intra- and inter-assay coefficients of variation for repeatability were below 1%. This triplex qPCR method was shown to have good specificity, sensitivity, and reproducibility. Finally, the triplex qPCR method established in this study was compared with the nested PCR as recommended by the Chinese national standard (GB/T34750-2017) for H. parasuis, the PCR as recommended by the Chinese national standard (GB/T 19915.9-2005) for S. suis serotype 2, and the PCR as recommended by the Chinese agricultural industry standard (NY/T 564-2016) for P. multocida by detecting the same clinical samples. Both methods are reasonably consistent, while the triplex qPCR assay was more sensitive. In summary, triplex qPCR serves not only as a rapid and accurate detection and early prevention method for these pathogens but also constitutes a robust tool for microbial quality control in specific pathogen-free pigs.

INSECTICIDE SUSCEPTIBILITY IN TWO POPULATIONS OF Aedes aegypti L. (Diptera: Culicidae) FROM GUERRERO, MEXICO, AND RECOMMENDATIONS FOR THEIR MANAGEMENT

The Aedes aegypti L. mosquito is a vector of diseases such as classic and hemorrhagic dengue (DENV), chikungunya (CHIKV), Zika (ZIKV), yellow fever (YFV), and Mayaro (MAYV). In 2019 alone, in Latin America, there were 2.7 million cases and 1206 deaths. In Mexico, government programs for managing this pest include the elimination of larval habitats and chemical control of larvae and adults. The objective of this study was to evaluate the response of two larvae and adult populations of A. aegypti from the state of Guerrero, Mexico, under laboratory conditions, to insecticides with different modes of action and to make considerations for their management. In the bioassays, larvae showed susceptibility to permethrin, malathion, deltamethrin, and Bacillus thuringiensis var. israelensis; low resistance to Temephos and propoxur; as well as moderate resistance to Spinosad. Both adult populations showed resistance to permethrin and susceptibility to deltamethrin, while the Acapulco population showed resistance to alpha-cypermethrin. For larvae, Spinosad is suggested to be used in times of high incidence of dengue. During drought, it is advisable to include rotations of B. thuringiensis var. israelensis with organophosphates. For adults, the use of imidacloprid in combination with botanical insecticides is considered a rational alternative to rotations with organophosphates and pyrethroids.

Special issue: Botanical pesticides for crop protection

Special issue: Botanical pesticides for crop protection

Evaluation the Efficacy of Botanical Insecticides in Controlling Tomato Boll Worm (Helicoverpa zea) and Leaf Minor (Tuta absoluta) in WesternTigray, Ethiopia

Aim of the study was to evaluate botanical insecticides to control tomato boll worm and leaf minor in western Tigray, Ethiopia. Field experiment was conducted during 2018/2020 in main crop growing season at Humera. A total of five treatments (Green miracle, Neembicidene, Melatonin, Gm+ Neembicidene and control no sprayed) were used in the field experiment. The experiment was laid out randomized complete block design (RCBD) with three replications. The mean yield had a significant difference at (p<0.001) among the botanical insecticides. The highest mean yield was obtained from Neembicidene (348.8) followed by green miracle (195.8) Malathion (183), Malathion+GM (162.8), and control (84.2) qtha-1 respectively. The highest severity recorded from control was 85.41% for leaf severity and 71.3% for fruit severity. However, lowest recorded severity 18.73% for leaves and 4.55% for fruits were calculated from Neembicidene. The highest percent population reduction after chemical spray was recorded from Neembicidene (85.07%). Therefore, Neembicidene botanical insecticide recommended and promoted to verification trial to control tomato bollworm and leaf minor.

Efficacy of Botanical Insecticides for Controlling Cochineal Scale (Dactylopius opuntiae) Insect on Cactus (Dactylcompound sopius opuntiae) Plant at Southern Tigray, Ethiopia

Cochineal scale insects, scientifically known as D. opuntiae, are small insects that feed on the sap of cacti plants. These insects are notorious for their ability to rapidly reproduce and spread, causing significant damage to cactus populations. Tigray region, located in northern Ethiopia, has been particularly affected by the relentless attack of cochineal scale insects on its cacti. The aim of this study was to evaluate botanical insecticide to control cochineal scale insect of cacti plant in southern Tigray, Ethiopia. Field experiment was conducted during 2024 in off-season at Raya-azobo district. A total of five treatments; leave extract (Neem, Lantana camara and Pepper tree and liquid soap), salt+liquid soup, liquid soup, water and control (no sprayed)) were used in the field experiment. The experiment was laid out randomized complete block design (RCBD) with three replications. The mortality rate of cochineal scale insect had a significant difference at (p<0.001) among the treatments. The highest rate of mortality (free of cochineal scale insect) was calculated from the leave extract (100%) extracted from leaves. However, the increasing number of cochineal scale insect was observed from untreated (control) (+9.9%) followed by cladodes treated with water (45.29%). The current research findings provide strong evidence that botanical insecticide derived from plant leaves could be an effective solution for controlling cochineal scale insect infestations on cacti. These eco-friendly alternatives offer several advantages over synthetic pesticides in terms of reduced toxicity to non-target organisms. Beside; it should be promoted to further demonstration and popularization at farmer level in the coming off-season.

Effect of Different Concentrations of Tomato Leaf Extract on Aphid Control in Rape Production in Zimbabwe

Rape (Brassica napus) is an important vegetable crop grown by smallholder farmers in Zimbabwe to achieve food and nutritional security. However, productivity and quality of rape are greatly dampened by aphids which reduce its palatability and quality. Chemical pesticides, while effective, pose environmental risks and can lead to pest resistance and resurgence, besides residual effects and bioaccumulation along the food chain. Tomato leaves are rich in phenolic and flavonoid compounds, that have shown promise as a botanical pesticide against aphids in other crops. This research aimed to establish the aphicidal components in tomato leaf extract using TLC and UV-Vis Spectroscopy; establish toxicity of the extract using laboratory bioassay, investigate the potential of different concentrations of tomato leaf extracts as a natural, environmentally friendly and sustainable approach to pest management against aphids in rape production at Kushinga Phikelela Agricultural College in Zimbabwe. A CRD with four treatments (0%, 20%, 40% and 60% of tomato leaf extract) and distilled water (negative control) replicated five times each was used. Aphid infestation (scored on a scale of 0-9), yield, leaf size, and plant height were measured fortnightly. Data was analysed for statistical significance using ANOVA while separation of significant means was done by Fisher’s Protected Least Significant Difference Test (LSD (5%). The results from combined analysis using TLC and UV- Vis Spectroscopy indicated that tomato leaf extract used in this research contained compounds (Solanine, Tomatine, Chaconine) which are known to be toxic to pests. There was a highly significant (p<0.001) difference among treatments on aphid mortality. The highest aphid mortality (95.57%) while the lowest (4%) was observed in 60% and 0% leaf extract respectively. Aphid infestation, leaf size and plant height were highly significant (P<0.001) during weeks 4, 6, 8 and 10 after transplanting. Aphid infestation in week 10 mean score was 8.8, 6.2, 3.8 and 0.8 for 0%, 20%, 40% and 60% tomato leaf extract respectively. Other parameters such as yield and leaf size were highest in the plots that received 60% tomato leaf extract sprays. Highly significant difference (P<0.001) in yield was observed in weeks 8 and 10, while significant difference (P<0.05) in yield was noted in weeks 4 and 6. However, in week two there were no significant differences among the treatments in yield and aphid infestation. Tomato leaf extracts contain secondary metabolites toxic to aphids and this can be used by resource constrained farmers. We recommend the use 60% tomato leaf extracts to control aphids in rape to sustainably achieve high yields.

Self-financing model for cabbage crops with pest management.

Smallholder farmers rely on their farm earnings to cover operating costs and generate income. That is not an easy task because of the pests, which reduce yields and generate plant protection costs. The farm yield and plant protection depend on the budget capacity of the farmer. In this work, we want to explore conditions for a sustainable and self-financing cabbage farm. We propose then a non-linear mathematical model for cabbage crops by considering the current account of the plantation as a dynamic variable. We assume that this variable increases due to the sale of cabbages, and provides for the seedling purchase, the plant protection costs, and the grower's income. In the first part, we analyze the model without pest management. We determine how the budget must be spent and we show the existence of a double transcritical bifurcation. We quantify the seasonal yield and income, and estimate the damage due to pest herbivory. In the second part, we analyze a slightly simplified version of our model and obtain the existence of a backward bifurcation. Furthermore, we show that botanical pesticides can be used to prevent pest spread with relatively low plant protection costs.

Microbial Biopesticides: An Ecofriendly Plant Protection Measures

Microbial pesticides possess active microbes capable of controlling plant pests in agriculture, horticulture, and forests. Microbes benefit plants through metagenomics, metabolomics, and strain enhancement efforts, keeping the loss below the economic threshold. The study looked at over 50 years of literature from various sources. Other investigations combined the factors used in this review study. They are biologically effective in controlling plant disease and insect pests. Since the modern agroecosystem depends more on chemical-based pesticides for pest control, microbial biopesticides are gaining popularity in terms of their natural, eco-friendly, and cost-effectiveness. Furthermore, the higher demand for organic food products further propels the future market for microbial pesticides. This review updates the mechanisms of controlling insect pests and plant diseases through biological control using biopesticides.

Unveiling the antibacterial potential of anthocyanins - a comprehensive review on this natural plant extract.

With the gradual prohibition of antibiotic fungicides, it is of great significance to develop high-efficient, nontoxic and environmental-friendly antimicrobial agents. Anthocyanin is a natural plant polyphenol pigment which shows antibacterial, anti-inflammatory and antioxidant effects through inhibiting the synthesis of bacterial cell wall, interfering bacterial respiratory metabolism, and inducing bacterial autolysis. As a typical antibacterial agent, anthocyanins have been widely used in various fields, including biological pesticides or feed additives in agricultural production, anti-inflammatory and antibacterial wound dressings in medicine, etc. However, the structure of anthocyanins is unstable, which limits its practical application. In this article, the biological activity, antibacterial mechanism and stabilization strategy of anthocyanins as antibacterial agents were reviewed. The safety, application scope and methods of anthocyanins were discussed. In addition, the challenges and development prospects of anthocyanin extract antibacterial technology were also prospected. This will be the direction for researchers to further explore and better apply anthocyanins to practical production and application.

Combination of a novel bacteriophage and d-serine effectively controls Vibrio parahaemolyticus growth in seafood

Seafood is an important high-protein and low-fat food source prone to spoilage and may harbor food poisoning bacteria. Vibrio parahaemolyticus is a gram-negative halophilic bacterium that causes food poisoning. It is heat labile and can be eliminated through heating; however, V. parahaemolyticus may be present in seafood for raw consumption, such as sashimi. Recently, the use of bacteriophages or phages has been proposed as a non-thermal inactivation method for microbial control. Here, we characterized VF16, a novel phage that infects V. parahaemolyticus, and evaluated the effectiveness of the combination of VF16 with the antimicrobial amino acid d-serine in controlling V. parahaemolyticus through antimicrobial testing in broth cultures and raw scallops. The morphology of VF16 was examined using transmission electron microscopy, which demonstrated that it had a long, flexible tail characteristic of a siphovirus. Genome sequencing revealed that VF16 is a novel phage belonging to the family Demerecviridae, subfamily Ermolyevavirinae, and genus Vipunavirus. Analysis of adsorption and one-step growth curve in a liquid medium indicated that Ca2+ and Mg2+ are necessary for one or more subsequent replication processes of VF16 but are not essential for its adsorption. The combination of VF16 and d-serine completely inhibited the regrowth of V. parahaemolyticus in the liquid medium and effectively suppressed its growth in the scallop samples. No VF16-resistant mutants were isolated from the scallop samples treated with VF16 alone or in combination with d-serine. The combination of phages and d-amino acids is an effective non-thermal inactivation method for controlling foodborne pathogens.

Manganese Complex-Gold Nanoparticle Hybrid for Biofilm Inhibition and Eradication.

Biofilms, which are resistant to conventional antimicrobial treatments, pose significant challenges in medical and industrial environments. This study introduces manganese complex-gold nanoparticles (Mn-DPA-AuNPs) as a hybrid strategy for biofilm inhibition and eradication. Upon exposure to green light, these nanoparticles significantly enhance the generation of reactive oxygen species (ROS), including hydrogen peroxide and superoxide. This activity substantially reduces the regrowth potential of the surviving bacteria within the biofilm, with marked efficacy noted in Pseudomonas aeruginosa PAO1. This study highlights the potential of integrating manganese complexes with gold nanoparticles to develop advanced antimicrobial agents against resistant biofilms, offering a promising approach to enhance microbial control in diverse settings.

Testing microbial pest control products in bees, a comparative study on different bee species and their interaction with two representative microorganisms

BackgroundThe evaluation of the impact of pesticides on non-target species, like bees, is a crucial factor in registration procedures. Therefore, standardized test procedures have been developed on OECD level assessing the effects of chemicals on honey bees or bumble bees. Unfortunately, these protocols cannot directly be adapted for testing products that contain microorganisms. Interest in the use of microorganisms has increased in recent years due to their specificity to target species while not harming non-target organisms. This study aimed to evaluate optimal conditions to assess the effects of microbial plant protection products on bee species according to currently available test protocols. Some of the most commonly used microorganisms for plant protection, Bacillus thuringiensis subspecies aizawai (B. t. a. ABTS 1857) and Beauveria bassiana (B. b. ATCC 74040) were tested on Apis mellifera, Bombus terrestris, and Osmia bicornis at different temperatures (18, 26, 33 °C) under laboratory conditions.ResultsExposure to the product containing B. t. a. ABTS 1857 resulted in higher mortality compared to B. b. ATCC 74040 in all tested bee species. A temperature-dependent effect towards higher mortality at higher temperatures of 26 °C or 33 °C was observed in O. bicornis exposed to both microorganisms. A. mellifera showed variable responses, but for B. terrestris there was mostly no effect of temperature when exposed to microorganisms in high concentrations. However, temperature affected longevity of bee species in the non-exposed control group. A. mellifera mortality increased with decreasing temperatures, while B. terrestris and O. bicornis mortality increased with increasing temperatures. A test duration of 15 or 20 days was found to be suitable for testing these microorganisms.ConclusionIn conclusion, 26 °C should be considered the worst-case scenario for testing B. bassiana on all tested bee species. For testing B. thuringiensis, a temperature of 33 °C is recommended for A. mellifera, whereas B. terrestris and O. bicornis should be tested at 26 °C.

Toxicity of botanical insecticides on different species of lace bugs

This study aimed to evaluate the toxicity of essential oils (EO) from Allium sativum (Amaryllidaceae) and Eucalyptus citriodora (Myrtaceae), commercial oil (CO) from Azadirachta indica (Meliaceae), and ethanolic extracts (EE) of Eugenia caryophyllata (Myrtaceae) and Piper nigrum (Piperaceae) on lace bugs (Hemiptera: Tingidae). The study also investigated the effects of exposure method, surfactant addition, and lace bug species on insecticide toxicity. The results indicated that assessing lace bug toxicity via contact with contaminated filter paper is a more effective method. Adding 5% detergent to E. citriodora EO 1% increased the mean mortality rates of the lace bug Gargaphia lunulata and Corythaica passiflorae from 34.11% to 94.00%. A. sativum EO 10%, E. citriodora EO 1%, and A. indica CO 1%, when combined with 5% detergent, caused high mortality rates in G. lunulata (76.00%, 77.67%, and 80.73%, respectively). However, these insecticides without detergent caused lower mortality in C. passiflorae (15.44%, 20.09%, and 11.15%, respectively), highlighting the significant impact of surfactant addition on the toxicity of essential and commercial oils. Piper nigrum EE 10% was toxic to all lace bug species. Conversely, the toxicity of Eugenia caryophyllata EE 10% varied among species, with mortality rates of 40% in G. lunulata, an average of 76.00% in Ulotingis sp. and Vartiga illudens, and 95.48% in C. passiflorae. In conclusion, despite variations in toxicity due to exposure method, surfactant addition, and lace bug species in laboratory bioassays, the botanical insecticides studied show promise for lace bug control.