Control Agents Research Articles

Temperature-Dependent Pupation Depth in the Oriental Fruit Fly Bactrocera dorsalis and Its Implications for Biological Control

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a notable agricultural pest that undergoes pupation in the soil. Mortality risk from predation and parasitism decreases as the depth of the pupal location increases from the ground surface, with a one-centimetre increase in depth causing a significant change. Soil properties, such as moisture and hardness, influence pupation depth, but the effect of temperature has not been fully tested. This laboratory study examined whether a biologically important variation in pupation depth (e.g., one centimetre) is caused by naturally experienced temperature variations (20 to 35 °C) in B. dorsalis. The temperature–pupation depth relationship revealed a unimodal pattern, with the deepest pupation occurring at intermediate temperature levels and shallower pupation at the two extreme temperature ranges. Strong quantitative effects were observed, with the highest mean pupation depth of 40.8 mm at 27.5 °C and the lowest mean pupation depth of 15 mm at 35 °C. The observed quantitative effect suggests that temperature can strongly affect pupal mortality from predators and parasitoids by influencing pupation depth. Future studies that reveal the ability of biological control agents to forage underground for pupae at different temperatures are awaited, as this is key information for evaluating the effectiveness of these agents.

Endophytic Bacillus velezensis GsB01 controls Gleditsia sinensis wilt by secreting antifungal metabolites and modulates symbiotic microbiota within trees.

Identifying effective biological control agents against fungal pathogens and determining their mechanisms of action are important in the control of plant diseases. In this study, we isolated an endophytic bacterial strain, GsB01, from the branches of asymptomatic Gleditsia sinensis. Multi-locus sequence analysis identified the strain as Bacillus velezensis. GsB01 exhibited significant antifungal activity against Thyronectria austroamericana, the causative agent of G. sinensis wilt. Liquid chromatography-mass spectrometry identified four consistently present antimicrobial compounds in GsB01 metabolite fractions with high antifungal activity: macrolactin A, bacillaene A, surfactin, and iturin. GsB01's active metabolite fractions altered the metabolic profiles of T. austroamericana, disrupting seven pathways, including arginine biosynthesis, nucleotide metabolism, purine metabolism, and the pentose phosphate pathway. Furthermore, absolute quantitative polymerase chain reaction analysis suggested that GsB01 may increase the abundance of endophytic bacteria in G. sinensis. The 16S rRNA amplicon sequencing revealed changes in the endophytic landscape in stems and roots following GsB01 introduction, particularly with significant variation in the dominant bacterial genera within the stems. The study highlights GsB01's potential against plant wilt and suggests that its antifungal activity is achieved by secreting antifungal metabolites. The study also recorded changes in the symbiotic microbiota within trees that had been infected with a pathogenic fungus and subsequently treated with an endophytic antagonistic bacterial strain. © 2024 Society of Chemical Industry.

Benefits of combining SGLT2 inhibitors and pioglitazone on risk of MASH in type 2 diabetes-A real-world study.

Both pioglitazone and glucagon-like peptide 1 receptor agonists (GLP1RA) alone improve metabolic dysfunction-associated steatohepatitis (MASH) in randomized clinical trials, whereas preclinical studies suggested MASH benefits with sodium glucose co-transporter 2 inhibitors (SGLT2i). In the real world, patients with type 2 diabetes often require multiple agents for glycaemic control. Here, we investigated the benefits of combining these agents on risks of MASH. Longitudinal changes in FibroScan-aspartate aminotransferase (FAST) score were measured in 888 patients with type 2 diabetes. Use of pioglitazone, GLP1RA and/or SGLT2i was defined as continuous prescriptions of ≥180 days prior to their last reassessment FibroScan. Multivariable logistic regression analysis was conducted to evaluate the associations between use of these agents and FAST score changes. Over a median follow-up of 3.9 years, the increasing number of these agents used was significantly associated with more reductions in FAST score (p for trend <0.01). Dual combination was independently associated with a higher likelihood of achieving low FAST score at reassessment than single use of any of these agents (odds ratio [OR] 2.84, p = 0.01). Among the different drug combinations, using SGLT2i and pioglitazone (median dose 15 mg daily) together, as compared to not using any of these three agents, was associated with a higher likelihood of both low FAST score at reassessment (OR 6.51, p = 0.008) and FAST score regression (OR 12.52, p = 0.009), after adjusting for changes in glycaemic control and body weight during the study. Combining SGLT2i and pioglitazone is a potentially useful strategy to ameliorate 'at-risk' MASH in patients with type 2 diabetes.

Compatibility and antimicrobial activity of silver nanoparticles synthesized using Lycopersicon esculentum peels.

Nanoparticles have gained worldwide attention as a new alternative to chemical control agents due to their special physiochemical properties. The current study focused on the environmentally friendly synthesis of silver nanoparticles (AgNPs) using Lycopersicon esculentum peel. In addition to studying the intrinsic cytotoxic effectiveness of Le-AgNPs contribute to their antibacterial, and antifungal activities and the effect of nanoparticles on the integrity of their morphological behavior. The initiative biosynthesis of L. esculentum silver nanoparticles (Le-AgNPs) was indicated by the color change of L. esculentum (Le) extract mixed with silver nitrate (AgNO3) solution from faint pink to faint brown. UV-visible spectroscopy, Dynamic light scattering (DLS), Fourier-transform infrared spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction techniques were used to characterize biosynthesized Le-AgNPs. Results of UV-visible spectroscopy recorded surface plasmon resonance at 310nm for SPR of 2.5. The DLS results showed particles of 186nm with a polydispersity index of 0.573. The FTIR spectrum indicated the existence of carboxyl, hydroxyl, phenolic, and amide functional groups. The HR-TEM analysis revealed quasi-spherical crystal particles of Le-AgNPs. Le-AgNPs had a negative zeta potential of - 68.44mV, indicating high stability. Bacillus subtilis ATCC 6633 and Escherichia coli ATCC 8739 were the most susceptible pathogens to Le-AgNPs inhibition, with inhibition zone diameters (IZDs) of 4.0 and 0.92cm, respectively. However, Listeria monocytogenes NC 013768 and Shigella sonnei DSM 5570 were the most resistant pathogens, with IZDs of 0.92 and 0.90cm, respectively. Le-AgNPs demonstrated good inhibitory potential against pathogenic fungi, with IZDs of 3.0 and 0.92cm against Alternaria solani ATCC 62102 and Candida albicans DSM 1386, respectively. The cytotoxicity effect was observed at a half-maximal inhibitory concentration (IC50) of 200.53μg/ml on human colon NCM460D normal cells.

Pseudomonas rhodesiae HAI-0804 suppresses Pythium damping off and root rot in cucumber by its efficient root colonization promoted by amendment with glutamate

Plant diseases caused by soil-borne fungi and oomycetes significantly reduce yield and quality of many crops in the agricultural systems and are difficult to control. We herein examine Pseudomonas rhodesiae HAI-0804, a bacterial biological control agent that was originally developed for control of bacterial diseases on the surface of vegetables, and assessed its efficacy at controlling soil-borne diseases caused by oomycetes. Strain HAI-0804 did not exhibit detectable antibiotic activity toward Pythium ultimum, a causal agent of damping-off and root rot; however, it effectively protected against Pythium damping-off and root rot in cucumber. Exogenous glutamate enhanced the efficacy of biocontrol, the production of siderophore pyoverdine, root colonization in cucumber plants, and the ratio of biofilm formation to planktonic cells. The epiphytic fitness of strain HAI-0804 appears to contribute to plant protection efficacy against a broad spectrum of pathogens for both above-ground plant parts and the rhizosphere.

Encapsulated Predatory Bacteria Efficiently Protect Potato Tubers from Soft Rot Disease.

Soft rot Pectobacteriaceae (SRP) are a group of destructive Gram-negative phytopathogens that can infect a wide range of plant hosts, including potatoes. There are no effective control agents available against SRP, making their management challenging. We have developed a novel approach to protect potato tubers against SRP. It makes use of encapsulated predatory Bdellovibrio bacteriovorus bacteria that, upon release from a polymeric carrier, prey upon SRP. We applied a carrageenan-trehalose-based formulation containing a B. bacteriovorus HD100 predator to prevent soft rot disease development in potato tubers, under various conditions. The dried formulation exhibited very high stability over an 18-month period at room temperature (∼25°C), in contrast to unencapsulated suspensions of the predator, in which viability decreased rapidly below detection level. The rehydrated formulation was as efficient as freshly grown unencapsulated predators and provided high protection in potted potato tubers, displaying an average of 50% reduction in disease parameters (e.g., tissue decay and disease index) under controlled conditions at 7 days postinoculation and planting. The protective effect provided by this formulation was maintained in longer-term trials (28 days) conducted in larger vessels within a net house under natural climate conditions, highlighting its potential for practical application in the field.

Wood microbiome variation and interactions with fungal symbionts of invasive ambrosia beetles

The microbiomes of plants can modulate the impacts of pests, including through interactions with microbiomes of pathogen vectors such as ambrosia beetles. While physical and chemical traits of plant hosts are known to affect beetle-carried microbes, how beetle and host microbiomes interact is seldom explored. We aimed to determine whether wood-inhabiting endophytes mediate host susceptibility to Fusarium dieback, an emergent tree disease complex that includes ambrosia beetle vectors. We studied three competent host tree species (Persea americana, Salix spp., Platanus racemosa) common in disease hot spots in agricultural and wildland habitats. Using culturing methods, we compared wood microbiomes of 319 attacked and 133 non-attacked trees across a network of 47 beetle-infested and 41 non-infested plots in southern California, USA. We conducted 1,148 in vitro assays to evaluate antagonism by wood-inhabiting endophytic fungi (60 species) and bacteria (40 species) to the Fusarium pathogens, finding 15 fungal and 11 bacterial species with clear antagonism to the pathogen. Such wood endophytes may potentially protect tree hosts as biological control agents. Antagonistic microbes were more common in attacked trees than in non-attacked trees, suggesting the abundance of antagonistic fungi and bacteria in the wood is insufficient to determine host susceptibility to attack or they are enriched in attacked trees. Wood-inhabiting microbial communities were consistently different between cultivated P. americana and wildland tree species, as there were some differences based on host attack status. Differences between attacked and non-attacked trees were reflected in different microbial consortia rather than the abundance of individual, antagonistic microbial species.

Biological control of locusts and grasshoppers: A review

Locusts and grasshoppers (Orthoptera: Acrididae) are pests of agricultural importance, devastating crops and pastures. This group includes hundreds of pest species and affects the livelihoods of one in every ten people worldwide. Their outbreaks can be chronic or episodic, with alternating periods of invasion and recession. Here, we review the natural enemies of locusts and grasshoppers in both their native and invaded ranges across the globe to assess the need for their conservation and maintenance as part of the natural suppression of outbreaks and to augment outbreak suppression as potential biological control agents. More than 70 natural enemies have been reported to attack locusts and grasshoppers, including entomopathogenic fungi, bacteria, nematodes, predatory insects, birds, reptiles, and mammals. Particular attention is given to the well-studied species of locusts and grasshoppers for which more information is available and to natural enemies in the locust-affected countries as part of the recent trend of looking for indigenous natural enemies. Such organisms can play a vital role in integrated pest management strategies for locusts and grasshoppers, particularly entomopathogens that can be incorporated with chemical pesticides into the management system. Among the organisms considered, Metarhizium acridum is noteworthy for inclusion in integrated pest management programs.

Biological Control of Aphids in China: Successes and Prospects.

Aphids are small, soft-bodied insects, and many are notorious pests of field crops, vegetables, fruit trees, ornamental plants, and trees. In China, there is an increasing emphasis on utilizing biological control agents, including aphidopathogenics, and selective pesticides for the management of aphids. In particular, preventive integrated pest management strategies with early interventions reduce the financial and environmental costs associated with treatments of outbreaks. Decades of progress have proved that biological control is a cost-effective and environmentally safe control option. Here, we review the history and progress of aphid control, with an emphasis on major natural enemies, mass-rearing, and conservation, and provide two successful cases, constraints, and future perspectives on aphid biological control in China.

The Use of Floseal Hemostatic Agent for Local Bleeding Control in Fungating Breast Cancer: A Case Report and Review of Literature

The Use of Floseal Hemostatic Agent for Local Bleeding Control in Fungating Breast Cancer: A Case Report and Review of Literature

Impact of the entomopathogenic fungus Metarhizium anisopliae (Metchnikoff ) Sorokin on Spodoptera frugiperda (J.E Smith), an invasive maize pest in Chad

The invasion of agricultural plots by Spodoptera frugiperda (J.E Smith) constitutes a serious constraint to the sustainable maize production in Chad. Since then, farmers have unsuccessfully used available chemical insecticides to control this pest at that respect, the present study evaluated the bio-efficacy of two strains (Chinese and Senegalese) of Metarhizium anisopliae on the pest, both under laboratory and field conditions. Laboratory results showed that both strains were virulent against FAW resulting in a mortality of 90 ± 5.77% for the strain from Senegal and 75 ± 5.00% for that from China. In the field, significant differences were observed among the four treatments tested, namely the two M. anisopliae strains (2.5 kg/ha), the control and Emamectin benzoate (20g/ha) for both the infestation of maize plants and FAW densities (P &lt;0.05). Meanwhile, maize grain yields were significantly the highest in plots treated with Emamectin benzoate followed by plots treated with either of the two strains of the fungus whose yields were statistically similar (df = 3; F = 27.13; P &lt;0.0001). This biopesticide was more virulent under laboratory and field conditions and could be a promising biological control agent against S. frugiperda as an alternative to synthetic insecticides. However, additional studies that evaluate the implementation cost of the microbiological control are very necessary for more objective and robust conclusions. Key words: Fall armyworm, microbiological control, Zea mays, Emamectin benzoate, biopesticides.

Bacterial communities in Asecodes hispinarum (Hymenoptera: Eulophidae) and its host Brontispa longissima (Coleoptera: Chrysomelidae), with comparison of Wolbachia dominance.

The endoparasitoid Asecodes hispinarum (Bouček) (Hymenoptera: Eulophidae) serves as an effective biological control agent against Brontispa longissima (Gestro) (Coleoptera: Chrysomelidae), a notorious palm pest. Endosymbionts found in parasitoids and their hosts have attracted significant attention due to their substantial influence on biocontrol efficacy. In this study, we employed 16S rRNA sequencing, polymerase chain reaction, and fluorescence in situ hybridization to assess the symbiotic bacteria composition, diversity, phylogeny, and localization in A. hispinarum and its host B. longissima. Our findings showed significant differences in the richness, diversity, and composition of symbiotic bacteria among different life stages of B. longissima. Notably, the bacterial richness, diversity, and composition of A. hispinarum was similar to that of B. longissima. Firmicutes and Proteobacteria were the dominant phyla, while Wolbachia was the dominant genera across the parasitoid and host. It was discovered for the first time that Wolbachia was present in A. hispinarum with a high infection rate at ≥ 96.67%. Notably, the Wolbachia strain in A. hispinarum was placed in supergroup A, whereas it was categorized under supergroup B in B. longissima. Furthermore, Wolbachia is concentrated in the abdomen of A. hispinarum, with particularly high levels observed in the ovipositors of female adults. These findings highlight the composition and diversity of symbiotic bacteria in both A. hispinarum and its host B. longissima, providing a foundation for the development of population regulation strategies targeting B. longissima.

Barn Owls as a Nature-Based Solution for Pest Control: A Multinational Initiative Around the Mediterranean and Other Regions

Pest rodents cause extensive damage to crops worldwide. Up to 40% of global crop production is lost annually to pests and diseases, with rodents accounting for 15–30% of this loss amounting to billions of dollars each year. The current method of controlling rodent populations involves the extensive use of chemical rodenticides. While effective in the short term, these chemicals pose serious environmental and health risks, leading to secondary poisoning of non-target species and other long-term negative ecological consequences, underscoring the need to adopt more sustainable pest-control measures. Nature-Based Solutions (NbSs), on the other hand, are increasingly recognized for addressing environmental challenges such as climate change, biodiversity loss, and sustainable development, and they include actions that protect, sustainably manage, and restore ecosystems. In this context, Barn Owls (Tyto alba) are highly effective as a natural pest-rodent control agents in agro-ecosystems. The species has a wide distribution and adaptability to various environments, and its diet consists predominantly of small mammals, with rodents making up from 50–60% up to even 90–95% of the diet according to different geographical regions. Each Barn Owl family can consume thousands of rodents annually, creating a high potential to reduce crop damage and infestations. Deploying nest boxes in agricultural areas can significantly increase Barn Owl populations, ensuring continuous and effective rodent control. Limitations of this solution must also be taken into consideration such as predation on rodents and small mammals that are not pests, and possible competition with other nocturnal birds of prey. Ιn the current paper, we aim to introduce the concept of owls as a NbS for pest rodent control and outline the main challenges, pitfalls, advantages, and disadvantages of implementing this solution in a new geographical region, and all the necessary in-between steps (scientific, societal, administrative, educational) that have to be followed for a successful implementation. So far, several countries have successfully implemented Barn Owl nest box schemes, with Israel and Cyprus achieving reduction in the use of pesticides by 45% and 58%, respectively, whereas the project is spreading to other Mediterranean countries (Jordan, Palestine Authority, Greece, Morocco, Spain), in palm plantations in Malaysia and USA, and in the vineyards of Napa Valley in California. The success of Barn Owl nest box programs relies on integrating scientific research, societal needs, supportive policy frameworks, and education. Barn Owl nest box programs are both bottom-up and top-down initiatives, in need of the participation of farmers and local communities to establish and deploy the Barn Owl solution. Continuous research is also necessary to explore systematically Barn owl trophic ecology, foraging and breeding ecology, interactions with agricultural landscape, and land uses in temporal and spatial scales, and challenges such as habitat suitability, availability of nesting sites, and regional ecological conditions must also be addressed.

Combined Analysis of Metabolomics and Transcriptome Revealed the Effect of Bacillus thuringiensis on the 5th Instar Larvae of Dendrolimus kikuchii Matsumura

Dendrolimus kikuchii Matsumura (D. kikuchii) is a serious pest of coniferous trees. Bacillus thuringiensis (Bt) has been widely studied and applied as a biological control agent for a variety of pests. Here, we found that the mortality rate of D. kikuchii larvae after being fed Bt reached 95.33% at 24 h; the midgut membrane tissue was ulcerated and liquefied, the MDA content in the midgut tissue decreased and the SOD, CAT and GPx enzyme activities increased, indicating that Bt has toxic effects on D. kikuchii larvae. In addition, transmission electron microscopy showed that Bt infection caused severe deformation of the nucleus of the midgut tissue of D. kikuchii larvae, vacuoles in the nucleolus, swelling and shedding of microvilli, severe degradation of mitochondria and endoplasmic reticulum and decreased number. Surprisingly, metabolomics and transcriptome association analysis revealed that four metabolic-related signaling pathways, Nicotinate and nicotinamide metabolism, Longevity regulating pathway—worm, Vitamin digestion and absorption and Lysine degradation, were co-annotated in larvae. More surprisingly, Niacinamide was a common differential metabolite in the first three signaling pathways, and both Niacinamide and L-2-Aminoadipic acid were reduced. The differentially expressed genes involved in the four signaling pathways, including NNT, ALDH, PNLIP, SETMAR, GST and RNASEK, were significantly down-regulated, but only SLC23A1 gene expression was up-regulated. Our results illustrate the effects of Bt on the 5th instar larvae of D. kikuchii at the tissue, cell and molecular levels, and provide theoretical support for the study of Bt as a new biological control agent for D. kikuchii.

NompC regulates locomotion and touch sensation in Bactrocera dorsalis.

No mechanoreceptor potential C (NompC) is a major mechanotransduction channel with an important role in sensing of external mechanical stimuli by insects, which help these organisms to avoid injury and adapt to environmental changes. To explore the biological functions of NompC in Bactrocera dorsalis, a notorious agricultural pest, we successfully generated NompC knockout strains using clustered regularly interspaced small palindromic repeats (CRISPR) / CRISPR-associated nuclease 9 (Cas9) technology. BdorNompC knockout led to an adult lethal phenotype, with approximately 100% mortality at 3 d after eclosion. Morphological observation revealed that the legs and wings of BdorNompC knockout insects were deformed, while behavioral assays showed that the locomotion was impaired in both adults and larvae, relative to that of the wild-type strain. Moreover, BdorNompC knockout reduced gentle-touch response in larvae. These results suggest that BdorNompC is critical for B. dorsalis survival, and that this mechanosensation channel represents a potential new target for pest control agents. Our findings also represent novel evidence indicating that insect NompC is involved in modulating adult wing and leg morphology.

Fitness Costs in Diamondback Moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) Resistant to Lufenuron, A Chitin-Synthesis Inhibitor Insecticide

The diamondback moth (DBM), Plutella xylostella, is the main pest of Brassicas crops worldwide, and its recorded resistance to 101 active ingredients indicates it is difficult to control. The purpose of this study was to investigate the hypothesis that P. xylostella has fitness costs associated with its resistance to lufenuron, a chitin-synthesis inhibitor insecticide. Thus, concentration–mortality bioassays were performed for susceptible (REC-S), resistant (BZR-R) populations, their progenies F1 and F1′, and one established population without selection pressure (BZR-Rns) after four generations. A fertility life table was used to assess the biological performance of the REC-S and BZR-R. BZR-Rns of P. xylostella. The larval stage, longevity, and survival differed between populations. The reproductive rate (R0) was significantly lower in the F1 (♀R × ♂S) (28.19) and F1′ (♀S × ♂R) (34.06) progenies compared with their parents, but not with the relaxed BZR-Rns (39.39). The mean generation time (T), intrinsic rate of population growth (rm), and doubling time (DT) differed between REC-S and progenies, with fitness of 0.52 and 0.64 for F1 and F1′, respectively. Overall, the results suggest that the resistance of P. xylostella to lufenuron is stable and that low fitness costs appear to be associated with resistance to lufenuron, although heterozygotes showed lower fitness than their parents. Strategies such as preserving refuge areas, rotation of modes of action, etc., are essential for resistance management and prolonging the efficacy of control agents; this highlights the importance of integrated insecticide resistance management.

The benefits and potential of pre-emptive weed biological control: Three case studies in Queensland, Australia

Invasive weed species can have significant impacts on agriculture, biodiversity and livelihoods. The cost and feasibility of managing these species using conventional means can be prohibitive depending on the size of the infestations or the habitats in which they invade. Under these conditions, biological control is seen as a viable, sustainable means to manage many weeds. However, biological control can take many years and at considerable cost to achieve the desired level of control, due to the numerous steps that are involved, including native range surveys and host-specificity testing of potential agents. Pre-emptive biological control targeting particularly high-risk species prior to their arrival in a country or emerging weeds can be cost-effective, especially if the respective biological control agents have been utilized in other countries. While pre-emptive biological control of arthropods has been investigated previously, there are few examples of pre-emptive biological control of weed species. The invasive weed species, Chromolaena odorata, Mikania micrantha and Coccinia grandis have all been or are currently targets of pre-emptive biological control in Australia. Research on the gall fly Cecidochares connexa was initiated prior to its host, C. odorata being detected in Australia. Cecidochares connexa was eventually released in Australia to control C. odorata, after initial research on the agent found it to be suitably host specific and effective against the target weed. Cecidochares connexa has also been released in numerous other countries in Africa, Asia and the Pacific, where it is providing very good control. Australia funded research on the rust Puccinia spegazzinii as part of a project involving Fiji and Papua New Guinea while the target weed, M. micrantha was a target for eradication in Queensland. The rust was later approved for release in Australia to control M. micrantha following additional host-specificity testing. However, research funded by Australia overseas suggests that the rust may not be able to suppress M. micrantha populations below current levels. Consequently, while P. spegazzinii has been released in numerous countries now, it has not yet been field released in Australia. Biological control research in Australia on C. grandis is relatively new as the weed is relatively minor and not yet declared a target for biological control. Consequently, no biological control agents have yet been released in the country. Pre-emptive biological control of C. odorata and M. micrantha has been particularly cost-effective, not just for Australia, but subsequently for numerous other countries where these weeds were well-established and problematic and the respective biological control agents were later released.

Prioritizing weeds for biological control development in the western USA: Results from the adaptation of the biological control target selection system

Nonnative invasive plants (weeds) negatively impact native ecosystems, and their effects are likely to increase with continuing global trade. Biological weed control has been employed as a cost-effective and sustainable management option for weeds in the USA since 1902. Biological control programs require careful prioritization of target weeds to ensure the most appropriate targets are selected to obtain the greatest beneficial outcomes with available resources. The Biological Control Target Selection (BCTS) system was developed by researchers in South Africa as an objective, transparent approach to prioritizing new weed biological control targets. The BCTS system was recently modified and applied to 295 state-regulated weeds in the western USA for which no biological control agents have yet been released. This paper presents the results of that application, identifying the most suitable candidates for new biological control programs as well as problematic weeds for which the likelihood of successful biological control is low.Top-ranked species in the western USA are biennial or perennial weeds that occur in stable habitats, are established in more than one state, have traits deemed difficult to control with conventional methods, have large negative impacts and no conflicts of interest outside of the horticultural industry, and have substantial information available on potential biocontrol agents. Fifteen of the 20 top-ranked species are already targets of ongoing biological control programs in the USA. When species with current programs are excluded from the analysis, the next 20 top-ranked species largely differ by having less information available on potential biological control agents and having native or economically important congeners in the USA. Results from this framework provide valuable insights to the prioritization of current and future biocontrol research programs in the western USA.

Aerial Systems for Releasing Natural Enemy Insects of Purple Loosestrife Using Drones

Lythrum salicaria (purple loosestrife) is an invasive species that displaces native wetland flora in the USA. The detection and manual release of biological control agents for L. salicaria is challenging because L. salicaria inhabits many inaccessible areas. This study was conducted to develop aerial systems for the detection of L. salicaria and the release of its natural enemy, Galerucella calmariensis (Coleoptera: Chrysomelidae). We determined the optimal sensors and flight height for the aerial detection of L. salicaria and designed an aerial deployment method for G. calmariensis. Drone-based aerial surveys were conducted at various flight heights utilizing RGB, multispectral, and thermal sensors. We also developed an insect container (i.e., bug ball) for the aerial deployment of G. calmariensis. Our findings indicated that L. salicaria flowers were detectable with an RGB sensor at flight heights ≤ 15 m above the canopy. The post-release mortality and feeding efficiency of G. calmariensis did not significantly differ from the control group (non-aerial release), indicating the feasibility of the targeted release of G. calmariensis. This innovative study establishes a critical foundation for the future development of sophisticated aerial systems designed for the automated detection of invasive plants and the precise release of biological control agents, significantly advancing ecological management and conservation efforts.

Biocontrol potential of Bevibacillus brevis HK544 for fungal plant diseases

Chemical fungicides have been widely used to control plant diseases caused by fungal pathogens. Still, the overuse of these fungicides has led to concerns about the hazards to humans, animals, and the environment and an increase in fungicide resistance. Interest in biocontrol agents with strong antimicrobial activity has significantly increased to counteract the escalating risks of chemical fungicides. Our previous study found that a soil-born microbe, Brevibacillus brevis HK544, exhibited a promising antifungal activity against a plant pathogen, Fusarium graminearum, with edeine B1 identified as the active compound. Herein, we extended our study to investigate the in vitro and in vivo antifungal spectrum of B. brevis HK544, including edeine B1, against various plant pathogenic fungi and evaluated the possibility that B. brevis HK544 could be used in combination with chemical fungicides to enhance the disease control efficacy. With an in vitro broad-spectrum antifungal activity, the B. brevis HK544 culture filtrate, culture broth, and metabolite edeine B1 exhibited a promising disease control efficacy against tomato gray mold and tomato late blight among the tested fungal diseases. Based on the in vitro antifungal activity against Botrytis cinerea, when edeine B1 was combined with various chemical fungicides, the highest average synergy score among the tested combinations was observed in the edeine B1 and benomyl combination. The co-application of the B. brevis HK544 culture filtrate and benomyl improved the disease control efficacy against gray mold disease, supporting the in vitro result. Taken together, our results show that B. brevis HK544 has potential as a biological control agent for controlling plant pathogenic fungi and also that B. brevis HK544 could be combined with chemical fungicides to enhance the efficacy of antifungal agents.