Potential Biological Control Agent Research Articles

Genomic Insight into a Potential Biological Control Agent for Fusarium-Related Diseases in Potatoes: Bacillus cabrialesii Subsp. cabrialesii Strain PE1

Bacillus strain PE1, which was isolated from potatoes harvested in the Yaqui Valley, Mexico, was evaluated as a potential biological control agent against Fusarium languescens. The draft genome sequence was obtained through Illumina NovaSeq sequencing, revealing a genomic size of 4,071,293 bp, with a G + C content of 44.13%, an N50 value of 357,305 bp, and 27 contigs. The taxonomic affiliation was confirmed by analyzing the 16S rRNA gene and overall genome relatedness indices (OGRIs) and constructing a phylogenomic tree based on the whole genome, which showed a close relationship to Bacillus cabrialesii subsp. cabrialesii. Genomic annotation using RAST and Prokka identified 4261 coding DNA sequences (CDSs) distributed across 331 subsystems, highlighting genes associated with biocontrol, stress response, and iron acquisition. AntiSMASH 7.1 was used for genome mining, revealing seven biosynthetic gene clusters that potentially produce biocontrol-related metabolites. In vitro assays confirmed the antagonistic activity of strain PE1 against Fusarium languescens CE2, demonstrating its potential to inhibit mycelial growth. The study provides a genomic basis for investigating B. cabrialesii subsp. cabrialesii PE1 as a potential biological control agent in potato production.

Investigating the host finding behaviour of the weevil Phytobius vestitus for the biological control of the invasive aquatic weed Myriophyllum aquaticum

Biological control programmes involve pre-release studies that include host range tests to predict likely negative effects on native species. Behavioural responses of potential biological control agents to olfactory signals emitted by target and non-target species provide information on the host-finding and selection behaviour for safer agent selection. The weevil Phytobius vestitus (Coleoptera: Curculionidae) was identified as a potential biological control agent for the sustainable management of the aquatic weed Myriophyllum aquaticum (Haloragaceae). Using olfactometer-based bioassays, we analysed the host-finding and host-selection behaviour of P. vestitus across a variety of plant species closely related to M. aquaticum using a glass olfactometer. We further analysed the volatile organic compounds emitted by the target and non-target plant species to explain the weevil's observed preferences. We demonstrated that P. vestitus was able to recognise and discriminate between eight closely related Haloragaceae plant species and was significantly more attracted to the olfactory cues emitted by the target plant, M. aquaticum, compared to the other plant species. This study provides a first important indication of the specificity of P. vestitus and shows the role of plant chemistry in host selection and the possibility of refining host range assessment for potential biological control agents. However, exhaustive risk assessment for possible release into targeted new environments still requires further investigations.

Assessing the Prey Specificity of Neoleucopis spp. against Marchalina hellenica

Marchalina hellenica Gennadius (Hemiptera: Marchalinidae) is a scale insect native to Greece and Turkey and presently invasive in Australia, where it damages pine plantations. The silver fly, Neoleucopis kartliana Tanasijtshuk (Diptera: Chamaemyiidae), is the most abundant predator of M. hellenica in Greece and is presently being investigated as a potential biological control agent following the scale’s introduction in Australia. This study, conducted in Northern Greece, revealed the presence of a second lineage, closely related to N. kartliana, referred to as Neoleucopis n. sp. B. Field surveys and laboratory experiments were conducted on M. hellenica and a taxonomically related scale insect, Icerya purchasi Maskell (Hemiptera: Monophlebidae), to test the larval growth and survival of the flies on the two prey species and assess their specificity for M. hellenica. The results suggest that both Neoleucopis spp. exhibit a high preference for M. hellenica when compared to I. purchasi. Larval growth was higher on M. hellenica than on I. purchasi but the difference was significant for N. kartliana only. Survival was significantly higher for both predators when provided M. hellenica compared to I. purchasi. Field surveys showed that both predators are abundant on M. hellenica colonies, whereas none of the two Neoleucopis lineages was found to have preyed on I. purchasi.

Biocontrol efficiency and potential mechanism of streptomyces distatochromogenes XT34 against postharvest anthracnose caused by colletotrichum musae on banana fruit

Banana anthracnose caused by Colletotrichum musae is a serious postharvest disease. Use of fungicides has potential adverse effects on the environment safety and human health. Application of biological control agents (BCA) is a promising strategy for managing postharvest fruit diseases. In this study, Streptomyces sp. XT34 was isolated from the banana rhizosphere soil and exhibited a strong antifungal activity against C. musae. Combining the phenotypic and whole-genomic alignment, strain XT34 was identified as Streptomyces diastatochromogenes. Strain XT34 extracts reduced the disease incidence of anthracnose and maintained the fruit quality of banana. Treatment of extracts reduced the colonization of C. musae on fruit surface. The activity inhibition of cell wall-degrading enzymes maintained the cell-wall strength of fruit. The activity increase of defense enzymes contributed to the low disease symptom. It was supported by the differentially expressed genes (DEGs) related to supramolecular fiber organization and flavonoid biosynthesis. In addition, spore germination of C. musae was effectively inhibited by extracts. The morphology of mycelia and spore become wrinkled and ruptured. The treatment of extracts increased the optical density of A260 and soluble sugar and protein contents of C. musae. The integrity of cell membrane was also destroyed, reflecting on an increase in electrical conductivity and malondialdehyde. Several metabolites were found in the genome of strain XT34 using antiSMASH. Eleven volatile compounds were identified by gas chromatography-mass spectrometer (GC-MS). Notably, strain XT34 and extracts exhibited a broad-spectrum antifungal activity against eight phytopathogenic fungi. Hence, S. diastatochromogenes XT34 provides a potential BCA to control banana anthracnose.

Pseudomonas siderophores: production, spectrophotometry detection and Botrytis suppression

Siderophores are iron-chelating agents produced by almost all microorganisms in response to iron deficiency. Due to the requirement of iron for cell growth and metabolism, siderophore-mediated acquisition of iron plays a central role in determining the ability of different microorganisms to colonize plant roots and contributes to microbial interactions in the plant rhizosphere. In this study, five new Pseudomonas (Q14B, Q13B, Q7B, Q6B, Q1B), isolated from the rhizosphere of tomato in Morocco, were examined for siderophores production capacity. The results show that all five isolates produced siderophores on both solid and liquid mediums. In liquid medium, the highest level of production is obtained by Q13B (53.8%).  Concerning siderophores’ chemical types, the five strains of Pseudomonas produce two types of siderophores hydroxamate and catecholate. It was shown by the peaks of absorbance in the wavelength 495 and between 420-450 nm for catecholate and hydroxamate-type siderophores respectively. The results showed that the production of siderophores is progressively inhibited with increasing concentrations of iron in the medium. The maximum production was obtained with a concentration of 0.5 μM, while the lowest was recorded at 10.0 μM of iron. The results of this study showed that the five Pseudomonas isolates producing siderophores could be potential biological control agents.

Evaluation of different Kabuli chickpea genotypes against Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in relation to biotic and abiotic factors.

The chickpea pod borer Helicoverpa armigera (Hübner) is a significant insect pest of chickpea crops, causing substantial global losses. Field experiments were conducted in Central Punjab, Pakistan, to investigate the impact of biotic and abiotic factors on pod borer population dynamics and infestation in nine kabuli chickpea genotypes during two cropping seasons (2020-2021 and 2021-2022). The crops were sown in November in both years, with row-to-row and plant-to-plant distances of 30 and 15 cm, respectively, following a randomized complete block design (RCBD). Results showed a significant difference among the tested genotypes in trichome density, pod wall thickness, and leaf chlorophyll contents. Significantly lower larval population (0.85 and 1.10 larvae per plant) and percent damage (10.65% and 14.25%) were observed in genotype Noor-2019 during 2020-2021 and 2021-2022, respectively. Pod trichome density, pod wall thickness, and chlorophyll content of leaves also showed significant variation among the tested genotypes. Pod trichome density and pod wall thickness correlated negatively with larval infestation, while chlorophyll content in leaves showed a positive correlation. Additionally, the larval population positively correlated with minimum and maximum temperatures, while relative humidity negatively correlated with the larval population. Study results explore natural enemies as potential biological control agents and reduce reliance on chemical pesticides.

First observation of the beetle Sericoderus lateralis consuming Cladosporium fulvum in a greenhouse tomato: potential for biological protection or risk to the crop?

For the first time, the mycophagous beetle Sericoderus lateralis (Gyllenhal, 1827) was documented feeding on tomato leaf mold ( Cladosporium fulvum Cooke, 1878) tissues. The phenomenon was observed during the years 2022 and 2023 in a hydroponic tomato greenhouse situated near the Czech-Polish border within the cadastre of Dolní Lutyně municipality in Czechia. Greenhouse and laboratory observations confirmed that adult and larvae feeding activity led to a reduction in tomato leaf mold lesions. In addition, there was a positive correlation between tomato leaf mold disease progression and increased populations of S. lateralis in the tomato crop. Petri dish observations confirmed egg laying occurred on a diet of tomato leaf mold. Further research is warranted to discern whether S. lateralis is a potential biological control agent for tomato leaf mold or if it acts to facilitate the spread of the disease by acting as a spore vector.

Microbial Interactions as a Sustainable Tool for Enhancing PGPR Antagonism against Phytopathogenic Fungi

Microbial interactions, which regulate the dynamics of eco- and agrosystems, can be harnessed to enhance antagonism against phytopathogenic fungi in agriculture. This study tests the hypothesis that plant growth-promoting rhizobacteria (PGPR) can also be potential biological control agents (BCAs). Antifungal activity assays against potentially phytopathogenic fungi were caried out using cultures and cell-free filtrates of nine PGPR strains previously isolated from agricultural soils. Cultures of Bacillus sp. BS36 inhibited the growth of Alternaria sp. AF12 and Fusarium sp. AF68 by 74 and 65%, respectively. Cell-free filtrates of the same strain also inhibited the growth of both fungi by 54 and 14%, respectively. Furthermore, the co-cultivation of Bacillus sp. BS36 with Pseudomonas sp. BS95 and the target fungi improved their antifungal activity. A subsequent metabolomic analysis using Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) identified fengycin- and surfactin-like lipopeptides (LPs) in the Bacillus sp. BS36 cell-free filtrates, which could explain their antifungal activity. The co-production of multiple families of LPs by Bacillus sp. BS36 is an interesting feature with potential practical applications. These results highlight the potential of the PGPR strain Bacillus sp. BS36 to work as a BCA and the need for more integrative approaches to develop biocontrol tools more accessible and adoptable by farmers.

Evaluation of Bacillus isolates as a biological control agents against soilborne phytopathogenic fungi.

Pesticides, used in agriculture to control plant diseases, pose risks to the environment and human health. To address this, there's a growing focus on biocontrol, using microorganisms instead of chemicals. In this study, we aimed to identify Bacillus isolates as potential biological control agents. We tested 1574 Bacillus isolates for antifungal effects against pathogens like Botrytis cinerea, Fusarium solani, and Rhizoctonia solani. Out of these, 77 isolates formed inhibition zones against all three pathogens. We then investigated their lytic enzyme activities (protease, chitinase, and chitosanase) and the production of antifungal metabolites (siderophore and hydrogen cyanide). Coagulase activity was also examined to estimate potential pathogenicity in humans and animals. After evaluating all mechanisms, 19 non-pathogenic Bacillus isolates with significant antifungal effects were chosen. Molecular identification revealed they belonged to B. subtilis (n = 19) strains. The 19 native Bacillus strains, demonstrating strong antifungal effects in vitro, have the potential to form the basis for biocontrol product development. This could address challenges in agricultural production, marking a crucial stride toward sustainable agriculture.

Development and reproduction of four predatory mites (Parasitiformes: Phytoseiidae) feeding on the spider mites Tetranychus evansi and T. urticae (Trombidiformes: Tetranychidae) and the dried fruit mite Carpoglyphus lactis (Sarcoptiformes: Carpoglyphidae)

The tomato red spider mite, Tetranychus evansi, a notorious crop pest, invaded New Zealand in 2020. In an effort to identify potential biological control agents for this species, we investigated the capabilities of four phytoseiid predators found in New Zealand—Amblyseius herbicolus, Amblyseius lentiginosus, Amblydromalus limonicus, and Neoseiulus californicus. For comparison, we also used the two-spotted spider mite, T. urticae, and the dried fruit mite, Carpoglyphus lactis, as prey for these predators. In our first experiment we monitored immature development and oviposition rate (over the first 5 days) of the phytoseiid predators when presented with the three prey species. While all four species of predators could develop and reproduce on the factitious (alternative and easily available) prey species C. lactis, they had limited success when feeding on T. evansi and T. urticae. Amblyseius herbicolus, A. lentiginosus, and Amblyd. limonicus were unable to reach adulthood when feeding on T. evansi and T. urticae in the presence of the protective webbing spun by the mites. While N. californicus matured when exposed to T. evansi reared on black nightshade leaves, it did not lay eggs—indicating potential limitations in prey suitability. In our second experiment, gravid females of all four predators failed to maintain their reproduction when provided with T. evansi in the presence of webbing. Neoseiulus californicus exhibited phenotypic plasticity in its developmental time, body size, and oviposition rate when feeding on the three prey species. This suggests that N. californicus has the flexibility to switch diets to survive during food scarcity, especially when their primary prey, T. urticae, is limited. This study is also the first to offer life history information about A. lentiginosus. Our findings underscore the difficulties of controlling T. evansi using phytoseiid predators and highlight the need for diversified pest management strategies, including the use of alternative insect predators or entomopathogenic fungi.

Streptomyces spp. Strains as Potential Biological Control Agents against Verticillium Wilt of Olive.

Verticillium wilt of olive (VWO) caused by Verticillium dahliae is considered a major olive (Olea europaea) disease in Mediterranean-type climate regions. The lack of effective chemical products against VWO makes it necessary to search for alternatives such as biological control. The main goal of this study was to evaluate the effect of six Streptomyces spp. strains as biological control agents (BCAs) against VWO. All of them were molecularly characterized by sequencing 16S or 23S rRNA genes and via phylogenetic analysis. Their effect was evaluated in vitro on the mycelial growth of V. dahliae (isolates V004 and V323) and on microsclerotia (MS) viability using naturally infested soils. Bioassays in olive plants inoculated with V. dahliae were also conducted to evaluate their effect against disease progress. In all the experiments, the reference BCAs Fusarium oxysporum FO12 and Aureobasidium pullulans AP08 were included for comparative purposes. The six strains were identified as Streptomyces spp., and they were considered as potential new species. All the BCAs, including Streptomyces strains, showed a significant effect on mycelial growth inhibition for both V. dahliae isolates compared to the positive control, with FO12 being the most effective, followed by AP08, while the Streptomyces spp. strains showed an intermediate effect. All the BCAs tested also showed a significant effect on the inhibition of germination of V. dahliae MS compared to the untreated control, with FO12 being the most effective treatment. Irrigation treatments with Streptomyces strain CBQ-EBa-21 or FO12 were significantly more effective in reducing disease severity and disease progress in olive plants inoculated with V. dahliae compared to the remaining treatments. This study represents the first approach to elucidating the potential effect of Streptomyces strains against VWO.

Effects of low temperatures on quiescence in Trichogramma evanescens Westwood and T. chilonis Ishii reared on Plodia interpunctella (Hübner): implications for mass rearing

The egg parasitoids of the genus Trichogramma are important potential biological control agents for a wide range of lepidopteran pests. Cold storage of host eggs has been proposed as a valuable technique for ensuring the release of sufficient parasitoid numbers whenever it is needed. In this context, the impact of low temperatures to induce quiescence in T. evanescens Westwood and T. chilonis Ishii was studied using eggs of Indian meal moth Plodia interpunctella (Hübner). Prepupae of the parasitoids were stored for 15, 30, 45, 60 and 75 d at 4 °C, following a 7 d period of acclimation at 10 °C. Both parasitoid species seem to survive unfavorable temperature conditions by entering a state of quiescence. Parasitism, adult emergence, sex ratio and progeny quality were not affected by cold storage in either parasitoid species for up to 30 d of storage. Parasitized host eggs of P. interpunctella can be stored for up to 60 d at 4 °C for both parasitoids, but there was no emergence at 75 d. General productivity values gradually decreased as the duration of storage lengthened for both species. Our results clearly reveal that the eggs parasitized by these species can be stored for up to 30 d at 4 °C in a state of quiescence without much loss of their performance compared to the control eggs.

Floral resources enhance fitness of the parasitoid Hadronotus pennsylvanicus (Hymenoptera: Scelionidae) but not biological control of its host Leptoglossus zonatus (Heteroptera: Coreidae).

The diet of adult parasitoid wasps is vital for their survival and reproduction. However, the availability of food resources, such as plant nectar, can vary widely in cropping systems, potentially affecting parasitoid fitness and thereby biological control of pests. The egg parasitoid Hadronotus pennsylvanicus (Ashmead) (Hymenoptera: Scelionidae) is a potential biological control agent of the pistachio pest Leptoglossus zonatus (Dallas) (Heteroptera: Coreidae). While H. pennsylvanicus is known to attack L. zonatus eggs in California, USA, parasitism rates in orchards are highly variable. Floral resource provisioning has the potential to enhance parasitoid longevity and thus improve parasitism rates, leading to reduced pest densities. Here, a combination of field and laboratory studies was used to assess the influence of flowering groundcovers on the reproductive fitness of H. pennsylvanicus and the abundance of L. zonatus. Evaluated groundcovers included oat (Avena sativa L.), cowpea (Vigna unguiculata L.), white mustard (Sinapis alba L.), and buckwheat (Fagopyrum esculentum Moench). Under laboratory conditions, buckwheat and mustard provided the greatest benefit to female H. pennsylvanicus longevity. However, females provided a buckwheat diet produced the greatest number of offspring over the course of their lifetime. In field trials, flowering groundcovers did not influence the abundance of H. pennsylvanicus nor parasitism rates on L. zonatus. While the availability of floral resources can improve the reproductive fitness of H. pennsylvanicus, the use of groundcovers in pistachio did not enhance biological control of L. zonatus.

Morphological characterization of antennal sensilla in Toxorhynchites theobaldi, Toxorhynchites violaceus, andLutziabigotiadults: a comparative study using scanning electron microscopy.

Some mosquitoes, including species of the genus Toxorhynchites, are known for actively preying on other mosquito larvae, making these predators valuable allies in the fight against vector-borne diseases. A comprehensive understanding of the anatomy and physiology of these potential biological control agents is helpful for the development of effective strategies for controlling vector populations. This includes the antennae, a crucial component in the search for hosts, mating, and selection of oviposition sites. This study utilized scanning electron microscopy to characterize the sensilla on the antennae of adult mosquitoes from two species that are exclusively phytophagous, including Toxorhynchites theobaldi and Toxorhynchites violaceus, as well asLutzia bigoti, which females are allegedly hematophagous. The types of sensilla in each species were compared, and five basic types of antennal sensilla were identified: trichoid, chaetic, coeloconic, basiconic, and ampullacea. The analysis also found that they were morphologically similar across the three species, regardless of feeding habits or sex. The identification and characterization of basic types of antennal sensilla in T. theobaldi, T. violaceus, andL. bigoti suggest that these structures, which play a crucial role in the behavior and ecology, have common functions across different mosquito species, despite differences in feeding habits or sex.

Trichopria anastrephae as a Biological Control Agent of Drosophila suzukii in Strawberries.

In South America, the resident pupal parasitoid Trichopria anastrephae Costa Lima (Hymenoptera: Diapriidae) is a potential biological control agent of the pest Drosophila suzukii Matsumura (Diptera: Drosophilidae). In the present study, we (1) examined the behavior of T. anastrephae towards different host (D. suzukii) and host-substrate (strawberry) cues in choice and non-choice bioassays in laboratory, and (2) examined the density-dependent parasitism of T. anastrephae in D. suzukii-infested strawberries in a greenhouse. When given a choice, female parasitoids walked longer over chambers with fruits infested with eggs, larvae, or pupae of D. suzukii, when compared to healthy uninfested strawberries, and over overripe fruits when compared to unripe or ripe fruits. In the greenhouse assay, we observed an increase in parasitism and a decrease in the number of D. suzukii emerging per fruit with an increase in the number of parasitoids released. Our results allow a better understanding of the behavior and parasitism of T. anastrephae in D. suzukii-infested strawberries and provide useful data for potential biological control programs using this parasitoid.

New morphological and biological contributions to adults and immature forms of Pissonotusparaguayensis (Fulgoromorpha, Delphacidae) in wetlands of Argentina.

In the search for insects as biological control agents for the water primrose, the delphacid Pissonotusparaguayensis (Delphacidae) was found on Ludwigiagrandiflorasubsp.hexapetala (Onagraceae) in a wetland of Central East Argentina. The morphology of the unknown females (brachypterous and macropterous) and immature stages are described and illustrated. Adults and nymphs were collected in wetlands of Del Plata River Basin, from Buenos Aires to the northeastern part of Argentina. A rearing methodology was developed to perform biological studies. Both winged forms and structural features of the female genitalia are described for the first time at the genus level. Eggs and immature stages are described and keyed; fifth nymphal instars may be easily recognised by the yellowish colouration, blackish on dorsal of head, thorax and abdomen with conspicuous yellowish pits, ventrally only darkened on base of frons extended to lower level of eyes and dorsal surface of antennomeres I and II, and legs with distinctive black marks at femoro-tibial joint and apex. The geographical distribution is updated, expanding its range into Argentina, making Buenos Aires the southernmost limit of the genus in America. Biological information of the species is also reported here: life cycle, fecundity, oviposition behaviour, and host plant. Field observations showed that P.paraguayensis breeds, feeds, and causes damage to L.g.subsp.hexapetala. This delphacid presents a certain degree of specificity to the Ludwigia species in the Jussiaea section in host specificity tests. More studies are required to test this species as a potential biological control agent.

A parasitoid regulates 20E synthesis and antibacterial activity of the host for development by inducing host nitric oxide production.

Parasitoids are important components of the natural enemy guild in the biological control of insect pests. They depend on host resources to complete the development of a specific stage or whole life cycle and thus have evolved towards optimal host exploitation strategies. In the present study, we report a specific survival strategy of a fly parasitoid Exorista sorbillans (Diptera: Tachinidae), which is a potential biological control agent for agricultural pests and a pest in sericulture. We found that the expression levels of nitric oxide synthase (NOS) and nitric oxide (NO) production in host Bombyx mori (Lepidoptera: Bombycidae) were increased after E. sorbillans infection. Reducing NOS expression and NO production with an NOS inhibitor (NG-nitro-L-arginine methyl ester hydrochloride) in infected B. mori significantly impeded the growth of E. sorbillans larvae. Moreover, the biosynthesis of 20-hydroxyecdysone (20E) in infected hosts was elevated with increasing NO production, and inhibiting NOS expression lowered 20E biosynthesis. More importantly, induced NO synthesis was required to eliminate intracellular bacterial pathogens that presumably competed for shared host resources. Inhibiting NOS expression down-regulated the transcription of antimicrobial peptide genes and increased the number of bacteria in parasitized hosts. Collectively, this study revealed a new perspective on the role of NO in host-parasitoid interactions and a novel mechanism for parasitoid regulation of host physiology to support its development.

Potential Biological Control Agents against Soft Rot Diseases Caused by Pectobacteria on Some Sugar Beet Cultivars

Sugar beet is one of the most economically important agricultural crops cultivated in many provinces of Turkey. Especially in recent years, there has been an increase in bacterial tuber rot due to factors related to climate change. In preliminary trials, soft rot disease by Pectobacterium caratovorum subsp. caratovorum (Pcc) and Pectobacterium betavasculorum (Pb) were detected predominantly in sugar beets in Central Anatolia. Today, some cultural measures and copper compounds are used against soft rot agents in sugar beet, but successful results cannot be obtained in preventing the disease. In this study, a total of 270 soil samples were taken from the rhizosphere of 10 different fields in 3 different periods in 3 different ecologically diverse districts (Çumra, Altınekin and Seydişehir) of Konya, one of the provinces with the highest amount of sugar beet production in Turkey. As a result of the isolations, a total of 3064 bacterial isolates were purified and 262 of them showed antibacterial activity against Pcc and Pb in vitro conditions. In addition, 15 antagonist bacteria with the highest inhibitory effect on the development of both pathogens were tested in greenhouse conditions, and according to the results obtained from here, 3 antagonists with the highest effect were tested in field conditions in the cultivation areas of 3 different districts named above. Biochemical, morphological and molecular diagnoses of antagonist bacteria with high efficacy were made. According to the results obtained, it has been concluded that rhizospheric bacteria with antagonistic effect have a success rate of 33-90% against Pcc and Pb pathogens, and that the biological products to be prepared in future studies can be used in ecological, climate friendly and within sustainable agricultural practices in sugar beet production areas.

Additional host range testing of Eucryptorrhynchus brandti (Coleoptera: Curculionidae) for the biological control of tree-of-heaven, Ailanthus altissima (Simaroubaceae) in the U.S.A.

ABSTRACT Ailanthus altissima, native to China, is a highly invasive plant in North America, Europe, and other continents. This species displaces native plants by forming dense clonal thickets. Ailanthus altissima is shade intolerant, quickly invades fields, rights-of-way, urban areas, and areas in forests disturbed by logging, fire, or pests. This species is also a primary host of the economically damaging spotted lanternfly, Lycorma delicatula, recently introduced into the U.S. Eucryptorrhynchus brandti is native to China and has been identified as a potential biological control agent of A. altissima. Oviposition studies conducted on 11 non-target plant species demonstrated that E. brandti oviposited only on the U.S. native Leitneria floridana. All non- Leitneria species had adult feeding of less than 2% compared to A. altissima, with no oviposition or larval development. Longevity of E. brandti in no-choice tests with L. floridana and L. pilosa subsp. ozarkana, was shorter and the weevils consumed less foliage compared to A. altissima. Seventeen percent of the L. floridana trees tested had larval feeding and 18 E. brandti adults emerged from 10 replicates. No L. floridana trees with larval feeding died. All the A. altissima trees with larval development died. Eucryptorrhynchus brandti is projected to be an effective agent against A. altissima and pose no significant risk to native North American plant species, with potential to be an additional management tool for the spotted lanternfly.

Isolation and Molecular Characterization of Brotowali (Tinospora crispa) Rhizosphere Bacteria Producing Siderophore from Dry Lands of Lombok Island

In the context of biopesticide development, siderophore-producing rhizosphere bacteria play an important role as potential biological control agents. Siderophores are complex organic compounds produced by microorganisms to bind and take up iron ions (Fe3+) from the surrounding environment. This compound is very important because iron is a nutrient necessary for life for many microorganisms and plants. The aim of this research was to determine the type and ability of bacteria in the rhizosphere of Brotowali (Tinospora crispa) to produce siderophores. The method used in this research is an exploratory descriptive type. The isolation results obtained from the North Lombok area obtained 5 samples with codes B4A1, B6A1, BT61, BT63 and BT83. The results of the bacterial isolate potency test with Media Kings showed that only isolate BT63 showed clear fluorescence when exposed to ultraviolet light. Meanwhile, the Arnow's Assay test showed that only BT63 colonies experienced a color change to pink. The results of the molecular identification of the potential bacteria, namely BT63, using the BLAST method using the GenBank data base at NCBI, show that it is closely related to the species Bacillus thuringiensis strain FDAARGOS 791. The results above show that the rhizobacteria isolated from Brotowali have the potential to be developed as a natural biopesticide that can be applied in the future.