Isaria Fumosorosea Research Articles

Effects of Pesticides on the Survival of Rove Beetle (Coleoptera: Staphylinidae) and Insidious Flower Bug (Hemiptera: Anthocoridae) Adults.

This study determined the direct, indirect, or both effects of pesticides on the rove beetle, Dalotia coriaria (Kraatz) (Coleoptera: Staphylinidae), and the insidious flower bug, Orius insidiosus (Say) (Hemiptera: Anthocoridae). The pesticides evaluated were Capsicum oleoresin extract, garlic oil, and soybean oil; cyantraniliprole; flupyradifurone; GS-omega/kappa-Hxtx-Hv1; Isaria fumosorosea; tolfenpyrad; pyrethrins; and spinosad. One experiment was conducted in a greenhouse with rove beetle adults exposed to growing medium applications of cyantraniliprole. The number of live and dead rove beetle adults was determined after 10 d. Four additional experiments were conducted under laboratory conditions. Rove beetle or insidious flower bug adults were individually placed into Petri dishes with filter paper treated with the pesticides. After 24, 48, 72, and 96 h, the number of live and dead adults of both natural enemies was recorded. GS-omega/kappa-Hxtx-Hv1 (VST-006340LC); tolfenpyrad; Capsicum oleoresin extract, garlic oil, and soybean oil (Captiva); and Isaria fumosorosea were not directly harmful to O. insidiosus (80-100% adult survival). Likewise, the pesticides such as tolfenpyrad, Captiva, and I. fumosoroea were not directly harmful to D. coriaria (80-100% adult survival). D. coriaria was more sensitive to VST-006340LC (40% survival) than O. insidiosus (100% survival), whereas O. insidiosus was more sensitive to flupyradifurone (0% survival) than D. coriaria (80% and 40% survival for both rates tested, respectively). The pesticides pyrethrins, spinosad, flupyradifurone, and combinations of tolfenpyrad and Captiva were directly harmful (<50% adult survival) to both natural enemies. However, none of the pesticides tested affected the ability of O. insidiosus adults to feed on western flower thrips adults.

PTP1B Inhibitors from the Entomogenous Fungi Isaria fumosorosea.

Protein tyrosine phosphatase 1B (PTP1B) is implicated as a negative regulator of insulin receptor (IR) signaling and a potential drug target for the treatment of type II diabetes and other associated metabolic syndromes. Thus, small molecule inhibitors of PTP1B can be considered as an attractive approach for the design of new therapeutic agents of type II diabetes and cancer diseases. In a continuing search for new PTP1B inhibitors, a new tetramic acid possessing a rare pyrrolidinedione skeleton named fumosorinone A (1), together with five known ones 2–6 were isolated from the entomogenous fungus Isaria fumosorosea. The structures of 2–6 were elucidated by extensive spectroscopic analysis. Fumosorinone A (1) and beauvericin (6) showed significant PTP1B inhibitory activity with IC50 value of 3.24 μM and 0.59 μM.

Enhanced activities of acetylcholinesterase, acid and alkaline phosphatases in Helicoverpa armigera after exposure to entomopathogenic fungi

The toxicity of entomopathogenic fungi, Metarhizium anisopliae (isolates Ma-11.1 and Ma-4.1), Isaria fumosorosea (isolates If-02 and If-2.3) and Beauveria bassiana (isolates Bb-01 and Bb-08) to Helicoverpa armigera was assessed by measuring the activity of acetylcholinesterase (AChE) and acid/alkaline phosphatases after 48 h of exposure till 168 h. The results showed high AChE activity in the hemolymph, intestine and fat bodies samples of H. armigera exposed to higher concentrations of I. fumosorosea (If-02 and If-2.3), M. anisopliae (Ma-4.1), B. bassiana (Bb-08) between 72 -168h at 7×108 spores/mL concentration, while M. anisopliae (Ma-4.1) exhibited maximum acid phosphatases (ACP) activity at similar concentration in the hemolymph and intestine samples with similar duration of exposure. On the other hand, isolates If-2.3, Ma-4.1 and Bb-08 showed maximum ACP activity during the same exposure duration. The results showed similar high alkaline phosphatases (ALP) activity in all body samples of H. armigera when treated with Ma-4.1 (7×108 spores/mL), while, isolate Bb-08 at similar concentration showed maximum ALP activity after 72 and 120 h of exposure. The increased production of these detoxification enzymes in this economic insect pest can possibly lead to the development of resistance against entomopathogenic fungi.

Compatibility and Efficacy of Isaria fumosorosea with Horticultural Oils for Mitigation of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae).

Horticultural oils are an important component of integrated management programs of several phytophagous arthropods and pathogens affecting fruit, ornamentals and vegetables in greenhouse and field production systems. Although effective against the target pest, their incompatibility with biological control agents can compromise efforts to develop eco-friendly management programs for important agricultural pests. In this study, we assessed the in vitro effect of selected refined petroleum oils used in citrus and other horticultural crops with a biopesticide containing the entomopathogenic fungi, Isaria fumosorosea (PFR-97) under laboratory conditions. Further, we used leaf disk bioassays to evaluate the combined efficacy of petroleum oils and I. fumosorosea against the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), a major pest of citrus in the United States. All five petroleum oil treatments (Orchex, Sun Pure, Conoco Blend -1, Conoco Blend -2, and JMS) were compatible with I. fumosorosea blastospores, as none of them were found to affect I. fumosorosea colony-forming units and radial fungal growth measured at 3, 6, 9, and 12 days post-inoculation. All mixed treatments performed better than I. fumosorosea alone against D. citri, where the highest mean survival time of D. citri was 12.5 ± 0.7 days. No significant differences in D. citri survival time and I. fumosorosea growth (fungal development index) on dead cadavers, which is important for determining their horizontal transmission, were observed when mixed with Orchex, Sun Pure, Conoco Blend -2, and JMS. Results indicated that horticultural oils in combination with I. fumosorosea could offer citrus growers an alternative treatment for integrating into their current management programs while battling against D. citri in citrus production systems. Due to their eco-friendly, broad-spectrum effect, it could provide control against various citrus pests, while also encouraging the retention of effective chemistries for a longer period in the marketplace. However promising, these combination treatments need to be tested further with I. fumosorosea under grove conditions to confirm their field efficacy.

Glycosylation of 6-methylflavone by the strain Isaria fumosorosea KCH J2.

Entomopathogenic fungi are known for their ability to carry out glycosylation of flavonoids, which usually results in the improvement of their stability and bioavailability. In this study we used a newly isolated strain of the entomopathogenic filamentous fungus Isaria fumosorosea KCH J2 as a biocatalyst. Our aim was to evaluate its ability to carry out the biotransformation of flavonoids and to obtain new flavonoid derivatives. The fungus was isolated from a spider’s carcass and molecularly identified using analysis of the ITS1-ITS2 rDNA sequence. As a result of biotransformation of 6-methylflavone two new products were obtained: 6-methylflavone 8-O-β-D-(4”-O-methyl)-glucopyranoside and 6-methylflavone 4’-O-β-D-(4”-O-methyl)-glucopyranoside. Chemical structures of the products were determined based on spectroscopic methods (1H NMR, 13C NMR, COSY, HMBC, HSQC). Our research allowed us to discover a new species of filamentous fungus capable of carrying out glycosylation reactions and proved that I. fumosorosea KCH J2 is an effective biocatalyst for glycosylation of flavonoid compounds. For the first time we describe biotransformations of 6-methylflavone and the attachment of the sugar unit to the flavonoid substrate having no hydroxyl group. The possibility of using flavonoid aglycones is often limited by their low bioavailability due to poor solubility in water. The incorporation of a sugar unit improves the physical properties of tested compounds and thus increases the chance of using them as pharmaceuticals.

Rapid discrimination of Isaria javanica and Isaria poprawskii from Isaria spp. using high resolution DNA melting assays.

The current study evaluates the potential of using high resolution DNA melting assays to discriminate species in the genus Isaria. The study utilizes a previously identified 103 base pair PCR amplicon, which was reported to be selective for Isaria fumosorosea. Our study finds the amplicon selective for Isaria javanica and Isaria poprawskii when assayed against all members of the genus. In addition, the high resolution melting profile of this amplicon can be used to discriminate between I. javanica, I. poprawskii and a 1:1 mixture of the two species. The practical application of this technique was confirmed using a bioassay on whitefly nymphs (Bemisia tabaci biotype B) inoculated with I. javanica, I. poprawskii or a 1:1 mixture of the two species. This assay provides a simple assay to identify these two species of entomopathogenic fungi.

Isaria fumosorosea KCh J2 Entomopathogenic Strain as an Effective Biocatalyst for Steroid Compound Transformations.

The catalytic activity of enzymes produced by an entomopathogenic filamentous fungus (Isaria fumosorosea KCh J2) towards selected steroid compounds (androstenedione, adrenosterone, progesterone, 17α-methyltestosterone and dehydroepiandrosterone) was investigated. All tested substrates were efficiently transformed. The structure of the substrate has a crucial impact on regio- and stereoselectivity of hydroxylation since it affects binding to the active site of the enzyme. Androstenedione was hydroxylated in the 7α-position to give a key intermediate in the synthesis of the diuretic-7α-hydroxyandrost-4-ene-3,17-dione with 82% conversion. Adrenosterone and 17α-methyltestosterone were hydroxylated in the 6β-position. Hydroxylated derivatives such as 15β-hydroxy-17α-methyltestosterone and 6β,12β-dihydroxy-17α-methyltestosterone were also observed. In the culture of Isaria fumosorosea KCh J2, DHEA was effectively hydroxylated in the C-7 position and then oxidized to give 7-oxo-DHEA, 3β,7α- and 3β,7β-dihydroxy-17a-oxa-d-homo-androst-5-ene-17-one. We obtained 7β-OH-DHEA lactone with 82% yield during 3 days transformation of highly concentrated (5 g/L) DHEA.

The potential of Isaria spp. as a bioinsecticide for the biological control of Nasutitermes corniger

ABSTRACTThe termite Nasutitermes corniger is a serious pest infesting urban areas of Brazil and many other countries. Control largely depends on synthetic pesticides whose indiscriminate use can impact the environment and the health of humans and other animals. Alternative strategies against insect pests, such as biological control by entomopathogenic fungi, could be effective while minimising these deleterious effects. We analysed the actions of the entomopathogenic fungi Isaria farinosa, Isaria fumosorosea, and Isaria javanica against the insect N. corniger. Our results indicated that the fungi examined were pathogenic against N. corniger, with I. farinosa ESALQ1355 being the most efficacious strain, resulting in the death of 95% of the workers (LC50 6.66 × 104 conidia/mL) and 85% of the soldiers (LC50 6.81 × 104 conidia/mL). This is the first report of the pathogenicity of Isaria spp. on N. corniger. These in vitro results suggest that I. farinosa ESALQ1355 demonstrates a significant biological potential for controlling N. corniger.

Pengaruh Kombinasi Aplikasi Jamur Paecilomyces fumosoroseus, Lem Perangkap, dan Insektisida Imidakloprid terhadap Empoasca sp.

In order to obtain an effective and efficient control method in integrated pest management, a research to know the effectiveness of combination treatments on Empoasca sp. on tea plant had been conducted. The trial was carried out at Gambung Experimental Station (1,250 masl) and designed in Randomized Complete Block design (RCB), with 8 treatments and 3 replications. The treatment tested comprised with A. Paecilomyces fumosoroseus (Pfr); B. sticky trap (ST); C. imidacloprid (I); D. Pfr + ST; E. Pfr + I; F. ST + I; G. Pfr + ST + I; and H. control. Pfr multiplied in rice medium 2.5 kg ha-1 and imidacloprid 0.125 L ha-1 were sprayed, while sticky trap was set in the middle of 5 m x 5 m plot. The parameters observed were attack intensity of Empoasca sp., population of Empoasca sp, and tea shoot production. The results showed that after 3 times application of all treatments revealed a decrease in the attack intensity of Empoasca sp. After the fourth application, combination treatment of sticky trap (ST) + imidacloprid (I) consistently showed higher efficacy than other treatments. In the sixth observation, the average of Empoasca sp. attack intensity of combination treatment (ST + I) was 15.95% with an average population of 0.67 Empoasca sp. per plot. In the meantime, tea shoot production was 33.64% higher compared with control.

The Entomopathogenic Fungi Isaria fumosorosea Plays a Vital Role in Suppressing the Immune System of Plutella xylostella: RNA-Seq and DGE Analysis of Immunity-Related Genes.

Most, if not all, entomopathogenic fungi have been used as alternative control agents to decrease the insect resistance and harmful effects of the insecticides on the environment. Among them, Isaria fumosorosea has also shown great potential to control different insect pests. In the present study, we explored the immune response of P. xylostella to the infection of I. fumosorosea at different time points by using RNA-Sequencing and differential gene expression technology at the genomic level. To gain insight into the host-pathogen interaction at the genomic level, five libraries of P. xylostella larvae at 12, 18, 24, and 36 h post-infection and a control were constructed. In total, 161 immunity-related genes were identified and grouped into four categories; immune recognition families, toll and Imd pathway, melanization, and antimicrobial peptides (AMPs). The results of differentially expressed immunity-related genes depicted that 15, 13, 53, and 14 up-regulated and 38, 51, 56, and 49 were down-regulated in P. xylostella at 12, 18, 24, and 36 h post-treatment, respectively. RNA-Seq results of immunity-related genes revealed that the expression of AMPs was reduced after treatment with I. fumosorosea. To validate RNA-Seq results by RT-qPCR, 22 immunity-related genes were randomly selected. In conclusion, our results demonstrate that I. fumosorosea has the potential to suppress the immune response of P. xylostella and can become a potential biopesticide for controlling P. xylostella.

Susceptibility of Diaphorina citri (Hemiptera: Liviidae) and Its Parasitoid Tamarixia radiata (Hymenoptera: Eulophidae) to Entomopathogenic Fungi under Laboratory Conditions.

Diaphorina citri (Kuwayama) is a global pest of citrus that transmits the bacteria associated with the disease, Huanglongbing. Entomopathogenic fungi and the parasitoid Tamarixia radiata (Waterston) are important biological control agents of this pest and likely to interact in D. citri populations. As a basis for interaction studies, we determined the susceptibility of nymphs and adults of D. citri and adults of the parasitoid T. radiata to six fungal isolates from the species Beauveria bassiana s.l. (Bals.-Criv.) Vuill. (isolates B1 and B3), Metarhizium anisopliae s.s. (Metsch.) (Ma129 and Ma65) and Isaria fumosorosea Wize (I2 and Pae). We conducted experiments evaluating infection levels in all three insect groups following inoculation with a series of conidial concentrations (1×104-1×108 conidia mL-1). Results showed that D. citri nymphs and T. radiata were more susceptible to fungal isolates than D. citri adults. Overall, B. bassiana and M. anisopliae isolates caused the greatest infection compared with I. fumosorosea isolates in all three groups of insects. Isolates B1 (B. bassiana) and Ma129 (M. anisopliae) infected a greater proportion of adults and nymphs of D. citri, respectively. Both isolates of B. bassiana caused greater infection in T. radiata compared with isolates of the other fungal species. We propose that isolates B1 and Ma129 are the strongest candidates for control of D. citri. Our results represent the first report of entomopathogenic fungi infecting T. radiata, and the basis for future studies to design a biological control programme that uses both agents more efficiently against D. citri populations.

Characterization and role of gut bacterium Bacillus pumilus on nutrition and defense of leafhopper (Amrasca biguttula biguttula) of cotton

Five culturable gut bacteria associated with single leafhopper [A. biguttula biguttula (Ishida)] (Hemiptera: Cicadellidae) of Guntur field population were characterized through morphological and 16S rDNA sequences. The characterized gut bacteria were Staphylococcus pasteuri, Enterococcus silesiacus, Bacillus amyloliquefaciens, Enterobacter asburiae and Bacillus pumilus. Among these, Bacillus pumilus was chosen for studying its role on host nutrition and defense. The role of the gut bacterium B. pumilus on insect defense against entomofungal pathogens and nutrition was studied under in vitro condition by dual culture technique and other bioassays. The gut bacterium B. pumilus inhibited the mycelial growth of all four major entomofungal pathogens. Maximum growth inhibition (2.0cm) was recorded on Beauveria bassiana followed by Metarhizium anisopliae (1.7cm), Paecilomyces fumosoroseus (1.6cm) and Lecanicillium lecanii (1.5cm) as compared to control. In vitro experiments proved the production of digestive enzymes such as cellulase, pectinase, amylase and protease from B. pumilus. The present study characterized the gut bacteria associated with A.biguttula biguttula and studied the role of the gut bacterium B.pumilus on host nutrition and defense against entomofungal pathogens for the first time in the world.

Efficacy of entomopathogenic fungi against adult Diaphorina citri from laboratory to field applications

The Asian citrus psyllid, Diaphorina citri, is the most serious threat to citrus crops worldwide, and its management relies exclusively on frequent applications of chemical insecticides. Entomopathogenic fungi may play an important role for regulating this citrus pest. Two virulent fungal strains, Isaria fumosorosea ESALQ-1296 and Beauveria bassiana ESALQ-PL63, were selected among 17 fungal isolates under laboratory conditions and caused 77.8 and 78.4% adult mortality, respectively, while in semifield trials the adult mortality reached up to 83.5% with B. bassiana and 80.6% with I. fumosorosea. The bioefficacy of these two fungi on D. citri adults was assessed through monthly applications during 1 year in a commercial citrus grove located in Itapetininga, Sao Paulo, Brazil. The application of I. fumosorosea ESALQ-1296 and B. bassiana ESALQ-PL63 was as effective as the chemical insecticides in most trials. The fungal-induced mortality of D. citri adults ranged from 96.1% in December 2011 to 57.8% in October 2012. This mortality level tended to build up with the increase in the maximum relative humidity; the percentage of sporulated cadavers was positively correlated with both higher relative humidity and rainfall but negatively associated with maximum temperatures. These results support the use of I. fumosorosea or B. bassiana as an eco-friendly biopesticide for the integrated management of D. citri.

Efecto del Hongo Isaria fumosorosea Wize Sobre la Herbivoría por los Adultos del Escarabajo de Margen Amarillo, Microtheca ochroloma Stal (Coleoptera: Chrysomelidae)

El escarabajo de margen amarillo, Microtheca ochroloma Stål (Coleoptera: Chrysomelidae) es una plaga que causa pérdidas económicas en la producción de crucíferas (Brassicaceae) en Argentina y el sureste de los Estados Unidos. El control biológico utilizando el hongo entomopatógeno Isaria fumosorosea Wize (Hypocreales: Cordycipitaceae) es una alternativa para reducir las poblaciones de esta plaga. Este estudio evaluó el efecto que tiene este hongo en la cantidad de herbivoría por los adultos del escarabajo al ser alimentados con hojas aplicadas con I. fumosorosea. Se evaluaron cuatro concentraciones (0.1, 0.5, 1.0 y 2.0 g) de la formulación PFR-97 20% WDG cepa Apopka 97 por 100 ml de agua destilada y se usó como tratamiento control únicamente agua destilada. Se realizaron dos ensayos, cada ensayo con 10 plantas de bok choy por tratamiento, cada planta con seis escarabajos. A los 7 días se midió el área foliar consumida por los escarabajos. En el primer ensayo, las plantas aplicadas con 1.0 y 2.0 g/100 ml sufrieron significativamente menos daño que el control. Para el segundo ensayo hubo diferencia significativa entre el control y la concentración 2.0 g/100 ml. El control tuvo 3.7 y 2.0% más daño comparado con los demás tratamientos en el primer y segundo ensayo, respectivamente.Ceiba, 2016. Volumen 54(2):118-126

Lack of resistance development in Bemisia tabaci to Isaria fumosorosea after multiple generations of selection

The emergence of insecticide resistant insect pests is of significant concern worldwide. The whitefly, Bemisia tabaci, is an important agricultural pest and has shown incredible resilience developing resistance to a number of chemical pesticides. Entomopathogenic fungi such as Isaria fumosorosea offer an attractive alternative to chemical pesticides for insect control, and this fungus has been shown to be an effective pathogen of B. tabaci. Little is known concerning the potential for the development of resistance to I. fumosorosea by B. tabaci. Five generations of successive survivors of B. tabaci infected by I. fumosorosea were assayed with I. fumosorosea. No significant differences in susceptibility to I. fumosorosea, number of ovarioles, or ovipostioning were seen between any of the generations tested. Effects of I. fumosorosea and cell-free ethyl acetate fractions derived from the fungus on the B. tabaci fat body, ovary, and vitellogenin were also investigated. These data revealed significant deformation and degradation of ovary tissues and associated vitellogenin by the fungal mycelium as well as by cell-free ethyl acetate fungal extracts. These data indicate the lack of the emergence of resistance to I. fumosorosea under the conditions tested and demonstrate invasion of the insect reproductive tissues during fungal infection.

Impact of Entomopathogenic Fungi on the Growth, Development, and Health of Cabbage Growing under Water Stress

Entomopathogenic fungi such as Beauveria bassiana, Isaria fumosorosea, and Metarhizium brunneum are commonly used in the form of biopesticides to manage various arthropod pests. These fungi also form endophytic and mycorrhiza-like relationships with plants. This study aimed at evaluating the impact of three entomopathogenic fungi on the growth, development, and health of cabbage plants grown under artificial lighting with limited water. Beauveria bassiana had a positive influence on the survival, growth, health, length, and dry weight of cabbage. Other fungi also had a positive impact on some of the measured parameters. Other beneficial bacteria and mycorrhizae were also compared with the entomopathogenic fungi. This is the first report evaluating the non-entomopathogenic role of three entomopathogenic fungi on cabbage plants.

Laboratory and Field Susceptibility of Drosophila suzukii Matsumura (Diptera: Drosophilidae) to Entomopathogenic Fungal Mycoses

Spotted wing drosophila (Drosophila suzukii Matsumura; Diptera: Drosophilidae) is a recently established invasive insect pest of berries and stone fruits. We tested the susceptibility of adult D. suzukii to infection by four species of entomopathogenic fungi: Beauveria bassiana (Bals.) Vuill., strains GHA and HF-23; Isaria fumosorosea Wize, strains FE-9901 and Apopka 97; Metarhizium anisopliae var anisopliae (Metschn.), strain F-52; and Metarhizium robertsii, strain DW-346; in laboratory bioassays. Scanning electron micrographs confirmed germination of conidia on D. suzukii integument. Exposure to conidia of all fungal isolates significantly increased mortality rates in comparison to untreated flies. In a subsequent bioassay of the two most virulent isolates, increasing pathogen dose from 0–16,000 conidia mm−2 of B. bassiana strain GHA increased fly mortality and proportion of sporulating cadavers. While fly inoculations with M. anisopliae at 0–4000 conidia mm−2 did not yield any measurable mortality response, a positive correlation was observed between dose and frequency of sporulating cadavers. In addition, we found that oocyte maturation rates were curtailed through one week of adulthood development after sub-lethal exposure to B. bassiana conidia. Despite promising laboratory results, a field cage experiment demonstrated that application of B. bassiana did not protect fruit from infestation. Taken together, these results show that entomopathogenic fungi are virulent against D. suzukii in the laboratory, but application in the field did not show promise.

Infection of the formosan subterranean termite, Coptotermes formosanus Shiraki, by the entomopathogenic fungus Isaria fumosorosea

this study investigates Isaria fumosorosea (Ifr) infection of and transfer among Formosan subterranean termites (FST). Prior to fungal exposure nestmates were fed Nile Blue, dye or Neutral Red dye. Blue FST were exposed to 6.3 x 109 fungal spores and mixed with red nestmates. At timepoints up to 168 h, termites were removed from each dyed group and fixed with osmium tetroxide. SEM observation at 24 h post-exposure showed most fungal conidia ungerminated and on the external cuticle of blue FST. At 48 h, germ tubes had formed on blue FST and penetrated the cuticle. Hyphae were observed externally at 96 h post-exposure. Fungal spores were visible on red FSt 96 h after placement with blue FSt, and hyphae were abundant at 168 h post-exposure. Blue FST were fixed, dehydrated, then embedded with a low viscosity epoxy. Embedded FST were sectioned with a microtome and visualized via light microscopy. Ifr penetrated the cuticle of blue FST at 48 h and were found on the interior of termites after 72 h. Transfer to red FST was confirmed 96 h post-exposure through visualization of spores.

Responses ofLiriomyza trifolii(Diptera: Agromyzidae) to Chemical and Biorational Insecticides

One of the most troublesome pests of snap beans is the American serpentine leafminer, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae). Growers commonly use abamectin, spinosad, and cyromazine to manage L. trifolii populations; however, the biological insecticide azadirachtin and the fungus Isaria fumosorosea Wize offer promising alternatives. We tested the effectiveness of these five insecticides for controlling L. trifolii under field conditions in southern Florida. Abamectin and spinosad were generally the most effective for reducing L. trifolii mines, larvae, and/or pupae. Cyromazine and azadirachtin were less effective than abamectin or spinosad, although better than I. fumosorosea or the untreated control. Isaria fumosorosea was the least promising treatment; however, it still performed better than the control in reducing L. trifolii mines, larvae, and/or pupae. As pesticide effectiveness increased, differences in numbers of mines, larvae, and pupae appeared to be reduced among the 5 dates that pesticides were sprayed. Overall, mines appeared to be more effectively controlled 1 to 2 d after treatment than after 7 d, whereas larvae and pupae were controlled equally throughout the period. The pesticides employed can be classified into 3 general groups based on modes of action: abamectin and spinosad (disrupters of insect neural and muscular systems), cyromazine and azadirachtin (disrupters of molting), and I. fumosorosea (invades the insect, produces a toxin, and halts feeding). Pesticides with at least two modes of action were each able to provide effective control. Alternating pesticides may therefore control L. trifolii while limiting the development of resistance in L. trifolii populations. ResumenUn de los peores plagas de habichuelas es el minador serpentino Americano, Liriomyza trifolii Burgess (Diptera: Agromyzidae). Frecuentemente, los productores utilizan abamectina, spinosad, y ciromazina para el control de L. trifolii. Sin embargo, azadiractina, una insecticida biologica, y el hongo, Isaria fumosorosea (Wize) AHS Br. Y G. Sm., pueden ofrecer alternativas eficaces. Pusimos a la prueba el rendimiento de todas estas insecticidas para el control de L. trifolii en el campo en el sur de Florida. Abamectina y spinosad fueron generalmente los mas eficaces para la reduccion de las minas, larvas, y/o pupas. Ciromazina y azadiractina aparecieron menos eficaz que abamectina o spinosad, pero mas eficaz que I. fumosorosea o el control no tratado. Isaria fumosorosea fue el tratamiento menos eficaz, aunque mas eficaz del control para la reduccion de las minas, larvas, y/o pupas. Como la eficacia de pesticidas aumento, las diferencias en los numeros de las minas, larvas, y pupas disminuyieron entre los 5 aerosoles. En general, las minas aparecieron controlado mas eficaz a 1–2 d despues de la rociada que despues de 7 d, pero las larvas y pupas fueron controlados por igual en todo el periodo. Sobre la base de modos de accion, los plaguicidas se clasificaron en tres grupos generales: abamectina y spinosad (disruptores de sistemas neurales y musculares en insectos), ciromazina y azadiractina (interrumpen la muda), y I. fumosorosea (invade el insecto y detiene la alimentacion). Cada de las pesticidas con modos de accion diferentes fue capaz de proporcionar un control eficaz. Alternando el uso de ellos puede controlar L. trifolii mientras illimitando el desarrollo de resistencia causada por el uso continuo de las pesticidas con un modo de accion unico. View this article in BioOne

Efficacy of Topical Application, Leaf Residue or Soil Drench of Blastospores of Isaria fumosorosea for Citrus Root Weevil Management: Laboratory and Greenhouse Investigations.

The efficacy of topical, leaf residue, and soil drench applications with Isaria fumosorosea blastospores (Ifr strain 3581) was assessed for the management of the citrus root weevil, Diaprepes abbreviatus (L.). Blastospores of Ifr were applied topically at a rate of 107 blastospores mL−1 on both the larvae and adults, and each insect stage was incubated in rearing cups with artificial diet at 25 °C, either in the dark or in a growth chamber under a 16 h photophase for 2 weeks, respectively. Percent larval and adult mortality due to the infection of Ifr was assessed after 14 days as compared to untreated controls. Leaf residue assays were assessed by feeding the adults detached citrus leaves previously sprayed with Ifr (107 blastospores mL−1) in Petri dish chambers and then incubating them at 25 °C for 2–3 weeks. Efficacy of the soil drench applications was assessed on five larvae feeding on the roots of a Carrizo hybrid citrus seedling ~8.5–10.5 cm below the sterile sand surface in a single 16 cm × 15.5 cm pot inside a second pot lined with plastic mesh to prevent escapees. Drench treatments per pot consisted of 100 mL of Ifr suspension (107 blastospores mL−1), flushed with 400, 900, or 1400 mL of water compared to 500, 1000, and 1500 mL of water only for controls. The mean concentration of Ifr propagules as colony forming units per gram (CFUs g−1) that leached to different depths in the sand profile per treatment drench rate was also determined. Two weeks post-drenching of Ifr treatments, larvae were assessed for percent mortality, size differences, and effect of treatments in reducing feeding damage to the plant root biomass compared to the controls. Topical spray applications caused 13 and 19% mortality in larvae and adults after 7 days compared to none in the control after 14 days, respectively. Adults feeding on a single Ifr treated leaf for 24 h consumed less than the control, and resulted in 100% mortality 35 days post-treatment compared to 33% in the untreated control. Although offered fresh, untreated leaves after 24 h, only adults in the control group consumed them. Ifr CFUs g−1 were isolated 8.5–10.5 cm below the sand surface for the 1000 and 1500 mL drench rates only, resulting in 2%–4% larval mortality. For all the Ifr drench treatments, no differences were observed in percent larval mortality and size or the effect of treatments in reducing feeding damage to the plant root biomass compared to the controls. These results suggest that the foliar application of Ifr may be an efficient biocontrol strategy for managing adult populations of D. abbreviatus; potential alternative larval management strategies are discussed.