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A preliminary evaluation of the potential of Beauveria bassiana for bed bug control


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Residual biopesticide treatments of Beauveria bassiana were tested against the bed bug Cimex lectularius. An oil formulation of conidia was applied to different substrates. Bed bugs were exposed for 1 h, transferred to an unsprayed environment and monitored for mortality. Separate bioassays evaluated the effect of bed bug strain, sex, life stage, and exposure substrate on mortality. Rapid mortality was observed in all bioassays, with bed bugs exposed to treated jersey knit cotton dying most rapidly. A further assay demonstrated efficient autodissemination of conidia from exposed bed bugs to unexposed bed bugs within artificial harborages.
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Short Communication
A preliminary evaluation of the potential of Beauveria bassiana for bed bug control
Alexis M. Barbarin
, Nina E. Jenkins
, Edwin G. Rajotte
, Matthew B. Thomas
Department of Entomology, Penn State University, 501 Agricultural Sciences & Industries Building, University Park, PA 16802, USA
Center for Infectious Disease Dynamics, Penn State University, 112 Merkle Lab, University Park, PA 16802, USA
article info
Article history:
Received 13 April 2012
Accepted 16 April 2012
Available online 25 April 2012
Cimex lectularius
Entomopathogenic fungi
Biological control
Insecticide resistance
Residual biopesticide treatments of Beauveria bassiana were tested against the bed bug Cimex lectularius.
An oil formulation of conidia was applied to different substrates. Bed bugs were exposed for 1 h, trans-
ferred to an unsprayed environment and monitored for mortality. Separate bioassays evaluated the effect
of bed bug strain, sex, life stage, and exposure substrate on mortality. Rapid mortality was observed in all
bioassays, with bed bugs exposed to treated jersey knit cotton dying most rapidly. A further assay dem-
onstrated efficient autodissemination of conidia from exposed bed bugs to unexposed bed bugs within
artificial harborages.
Ó2012 Elsevier Inc. All rights reserved.
1. Introduction
The human bed bug Cimex lectularius is a hematophagous insect
that requires blood meals for growth and development throughout
its life cycle. Over the past decade, bed bug infestations have grown
virtually exponentially in both North America and Europe (Hwang
et al., 2005). This resurgence in bed bug infestations has been
linked to increased international travel, changes in pest manage-
ment practices (including increased regulatory constraints remov-
ing certain chemical insecticides from operational use (Boase,
2007)) and the wide scale spread of insecticide resistance (Moore
and Miller, 2006; Romero et al., 2007; Seong et al., 2010). Insecti-
cide resistance, together with concerns over extensive use of
chemicals in the domestic environment (Sanborn et al., 2002), cre-
ate a need for safe alternative methods of bed bug control. One
candidate approach is the formulation of fungal entomopathogens
as novel biopesticides.
Entomopathogenic fungi lend themselves to development as
biopesticides because, like many conventional chemical insecticide
active ingredients, they act through contact. Fungal species such as
Beauveria bassiana and Metarhizium anisopliae are capable of infect-
ing a broad range of insect hosts and several biopesticide products
have been developed for use in horticulture and agriculture (Lacey
et al., 2008). Recently, research has extended to blood feeding in-
sects and disease vectors including mosquitoes (Scholte et al.,
2005; Blanford et al., 2005, 2011; Darbro et al., 2011), ticks
(Fernandes et al., 2011), tsetse flies (Maniania and Odulaja, 1998)
and triatomid bugs (Pedrini et al., 2009).
To date, there are no published studies on the efficacy of
entomopathogenic fungi against bed bugs. In this study, we evalu-
ated the efficacy of one candidate isolate of B. bassiana as a residual
biopesticide against the common bed bug in laboratory conditions,
considering effects of feeding status, sex, bed bug strain, life history
stage, and exposure substrate. Additionally, we evaluated autodis-
semination of conidia as a means to spread infection among bed
bug populations in untreated, inaccessible areas.
2. Materials and methods
2.1. Bed bugs
A pyrethroid-susceptible laboratory strain (Harlan; cultured
without introductions nor pesticide exposure since 1973) of bed
bugs (designated HS) was obtained from Virginia Polytechnic Insti-
tute and State University. A second ‘field’ strain (an amalgam of
several populations collected from cities across the US in 2005;
designated FS) was obtained from University of Minnesota. Both
strains were reared in our lab under standard conditions of 27 °C,
50% relative humidity (RH), and 14:10 (L:D) in glass rearing jars
containing folded filter paper (Whatman No. 1, 90 mm) for a har-
borage and offered a blood meal weekly via an artificial feeding
system (Montes et al., 2002).
2.2. Fungal isolate
B. bassiana I93-825 was maintained in long-term storage at
80 °C on microporous beads (Pro-Lab Diagnostics, Austin, TX,
USA). Conidia were mass-produced using our standard 2-stage pro-
duction system on barley flake (Jenkins et al., 1998; Anderson et al.,
0022-2011/$ - see front matter Ó2012 Elsevier Inc. All rights reserved.
Corresponding author. Fax: +1 814 865 3048.
E-mail address: (A.M. Barbarin).
Journal of Invertebrate Pathology 111 (2012) 82–85
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2011). Conidia were harvested using a Mycoharvester (Acis Manu-
facturing, Devon, UK), dried to 5% moisture content over silica gel,
sealed in foil laminated sachets and stored at 5 °C until use.
Conidia were formulated in oil containing 80% Isopar M (Exxon
Mobil) and 20% Ondina 22 (Shell) and adjusted to a concentration
of 1.6 10
conidia/mL (viability 94–98%).
2.3. Application of conidia to exposure substrate
Conidial formulations were applied to substrates (paper or cot-
ton jersey) at a rate of 3 10
using an airbrush
sprayer (Anderson et al., 2011), to give an equivalent volume appli-
cation rate of 20 mL/m
. Spore formulations were applied to HP™
Color-Laser Paper or jersey knit cotton, which were then cut into
9 cm circles. Control substrates were sprayed with blank oil formu-
lation only. After spraying, substrates were allowed to dry at room
temperature overnight. Coverage of conidia was verified by
extracting the conidia from three replicate, 2 cm
swatches in Iso-
par M and counting the resulting conidial suspension using an im-
proved Neubauer hemocytometer.
2.4. Exposing bed bugs to fungal spores
FS bed bugs were used in all experiments except that which
compared the susceptibility of the two strains. Most experiments
used adult bed bugs of mixed sex, which were removed from the
colony one day prior to exposure and fed 12 h prior to experimen-
tation. Variations to this procedure are described in the specific
methods for each study.
In all studies, three replicates of 10 bed bugs were exposed to
each treatment by placing them on pre-sprayed, dry substrate in
a Petri dish for 1 h. After exposure, bed bugs were placed on clean
filter paper in a Petri dish. All bed bugs were fed on day 7, 14, and
21 following exposure and mortality recorded daily for 21 d.
Cadavers were incubated under high humidity to confirm mycosis.
Survival data were analyzed using Kaplan–Meier survival analysis
(SPSS, software version 18). Differences in median survival time
between treatments were compared using the log-rank test.
2.5. Impact of feeding status, sex, and strain
All bioassays to evaluate the effect of feeding status, sex and
strain of bed bugs were conducted on HP™ Color-Laser Paper as
the test substrate. To evaluate the effect of feeding status, 60 adult
bed bugs of mixed sex were randomly selected from the FS colony
prior to feeding. Thirty bed bugs were left unfed (no blood meal for
14 d), while the remaining 30 were blood fed 12 h prior to expo-
sure and the bioassay conducted on three replicates of 10 bed bugs
as per the standard bioassay procedure.
To evaluate sex and strain differences, males versus females or
mixed sex populations from the HS and FS colonies were used,
2.6. Impact of sprayed substrate on conidial transfer
Adults of mixed sex from the FS colony were fed 12 h prior to
exposure and placed on either sprayed HP™ Color-Laser Paper or
jersey knit cotton for 1 h.
2.7. Impact of life history stage
FS bed bugs were grouped according to instar. Adult, first and
fifth instar bed bugs were selected as these life stages were most
easily distinguishable. All bed bugs were fed 12 h prior to expo-
sure. Three replicate groups of 10 bed bugs from each instar were
placed on treated jersey knit cotton for 1 h.
2.8. Autodissemination of conidia
Bed bugs were removed from the FS colony, fed, and placed into
30 mL diet cups in six groups of 20 and left overnight. The follow-
ing day, 10 bed bugs were removed at random from each group
and exposed to either treated or unsprayed jersey cotton (three
replicates) and allowed to remain in contact with the substrate
for 1 h. After exposure, bed bugs were returned to their respective
diet cups to comingle with the 10 unexposed bed bugs. A sterile fil-
ter paper harborage was provided. Mortality was assessed daily as
3. Results
There was no difference in mean survival times (MST) of treated
bed bugs regardless of feeding status (MST fed 4.30 ± 0.160 days,
unfed 4.17 ± 0.230 days, chi-square = 0.714, d.f. = 1, p= 0.398),
sex (MST males 4.60 ± 0.214 days, females 5.60 ± 1.070 days, chi-
square = 0.328, d.f. = 1, p= 0.567), or strain (MST HS 5.03 ± 0.559
days, FS 5.10 ± 0.552 days, chi-square = 0.259, d.f. = 1, p= 0.611)
(Fig. 1A–C). Mycosis was confirmed in 100% of cadavers.
Mean survival times of bed bugs exposed to sprayed jersey knit
cotton were significantly shorter than those exposed to sprayed
paper (MST jersey 3.03 ± 0.580 days, paper 4.30 ± 0.160 days chi-
square = 43.382, d.f. = 1, p60.001) (Fig. 1D).
All bed bug instars tested were susceptible to infection follow-
ing exposure to sprayed jersey material (MST 1st instar 3.00 ±
0.00 days, 5th instar 4.00 ± 0.048 days, adults 3.03 ± 0.033 days)
(Fig. 1E).
Bed bugs sharing harborages with conidia-exposed individuals
experienced significantly more mortality than in the control harbo-
rages (chi-square = 124.04, d.f. = 1, p60.000). Mean survival times
for adult bed bugs in the exposed treatment was 5.42 ± 0.532 days.
There was no control mortality in this experiment. Overall mortal-
ity in the treated group was 95%, demonstrating that practically all
of the unexposed beg bugs became infected when sharing the har-
borage with recently exposed individuals (Fig. 1F).
4. Discussion
B. bassiana (I93-825) was highly virulent to bed bugs, causing
rapid mortality (3–5 days) following short-term exposure to spray
residues. Infection levels were generally 100% indicating complete
susceptibility to fungal infection under these exposure conditions.
In a couple of assays 5–8% of individuals did not die, but re-expo-
sure of these few survivors resulted in infection and mortality (re-
sults not shown), suggesting sub-optimal pick up of spores
(especially from the paper substrate) rather than any physiological
resistance. Results were robust across six separate assays.
There were no striking differences in susceptibility due to bed
bug feeding status, sex, strain, or life stage. With respect to test
substrates, jersey knit cotton was a better substrate for conidial
transfer than paper, probably due to the relatively contoured sur-
face resulting in more conidia coming into contact with the insect
cuticle. These results demonstrate that choice of substrate is
important in both bioassay design and end product development.
Studies exploring transfer of conidia to mosquitoes following
short-term residual exposure also show substrate type to effect
infection levels and spore persistence (Farenhorst et al., 2011).
The current study focused on the lethal effects of infection, not
least because our bioassay system resulted in such rapid and
extensive mortality. In ‘field’ settings (i.e. in domestic environ-
ments where the fungus would be deployed) it is possible that
bed bugs might experience lower doses via transient exposures,
or when fungal spray residues begin to decay, resulting in slower
A.M. Barbarin et al. / Journal of Invertebrate Pathology 111 (2012) 82–85 83
Fig. 1. (A–C) Mean proportional survival of bed bugs exposed to paper sprayed with oil formulation of B. bassiana conidia at 3 10
(circles), or blank oil
formulation (squares) for 1 h. (A) Bed bugs blood-fed 12 h prior to exposure (black circles), or left unfed prior to exposure (grey circles). (B) Male (black circles) and female
(grey circles) bed bugs. (C) Harlan strain (black circles) and field strain (grey circles). (D) Mean proportional survival of adult field strain bed bugs exposed to sprayed paper
(grey circles) or cotton jersey (black circles) for 1 h. (E) Mean proportional survival of first instar (black circles), fifth instar (grey circles) and adult (open circles) bed bugs,
exposed to treated and untreated cotton jersey. (F) Mean proportional survival of adult bed bugs where only 50% of the population was exposed to fungus-treated cotton
jersey (black circles) or blank formulated control (squares), and the remaining bed bugs sharing the harborages were unexposed. All data points represent the mean (± SE) of
three replicates of 10 bed bugs except (F) where three replicates of twenty bed bugs were used.
84 A.M. Barbarin et al. / Journal of Invertebrate Pathology 111 (2012) 82–85
mortality. However, slower speed of kill might be of relatively little
consequence with respect to population suppression and ultimate
elimination from a residence. Bed bug nymphs typically take 4–
5 weeks to complete development and reach sexual maturity
(Omori, 1941). This relatively slow development provides many
days for a fungus to act while still preventing reproduction.
Furthermore, sub- or pre-lethal effects of fungal infection, which
include reduced feeding, mobility, and fecundity, are well docu-
mented in other systems (Blanford and Thomas, 2001; George
et al., 2011; Howard et al., 2010) and have the potential to supple-
ment lethal effects substantially.
Elimination of established bed bug infestations is challenging
because it is difficult to identify and target all concealed harborag-
es. However, bed bugs make nightly excursions in search of a blood
meal (Mellanby, 1939; Usinger, 1966). Therefore, development of
delivery systems based on barrier treatments, such as a ‘bed skirt’,
positioned between the harborages and the human host show
potential for effective control. In addition, our results suggest
the potential for efficient autodissemination of conidia via contact
with contaminated individuals. Our assay demonstrated that when
only 50% of a bed bug population was directly exposed to fungus,
total mortality exceeded 95%. Other studies have demonstrated
autodissemination of conidia (Scholte et al., 2004) and potential
for disease cycling following biopesticide spray applications
(Arthurs and Thomas, 1999; Thomas et al., 1995). Since bed bugs
are highly gregarious with all life stages aggregating in confined
harborages with humid microclimates (Usinger, 1966), horizontal
transmission could greatly increase the impact of fungal treat-
ments relative to conventional chemicals.
Overall, this study represents an important first step in develop-
ing B. bassiana as a biopesticide for use against bed bugs within no-
vel strategies of integrated pest management. Further research is
now required to develop appropriate formulations and delivery
systems to investigate population level impact under more realistic
‘semi-field’ and ‘field’ settings.
We thank D. Miller at Virginia Tech, Blacksburg, VA and J. Olson
at University of Minnesota-Twin Cities, Minneapolis–St. Paul, MN
for supplying the Harlan strain and Field strain of bed bugs respec-
tively. We are also grateful to Naworaj Archarya, who assisted with
conidia production, formulation and monitoring and Rebecca Hei-
nig for help with spray application and germination counts.
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... Genus Beauveria include entomopathogenic and endophytic fungi which are widely spread in different habitats [1][2][3]. Furthermore, many researchers reported that fungi in the genus Beauveria can produce enzymes for biotransformation and biodestructors [4,5]. On the other hand, the genus Beauveria is considered also a human pathogen where it causes opportunistic infections especially in patients with weak immune systems [6]. ...
... The application of B. bassiana has many advantages such as being an eco-friendly management compared to chemical pesticides where it is harmless to human health [8,[10][11][12]. For decades, several scientists have reported the importance of B. bassiana in reducing a range of nuisance insects, where it can induce direct insect mortality [2,13,14] and can also reach 90% reduction of life-time fecundity [15]. ...
Full-text available
The genus Beauveria include important entomopathogenic and endophytic fungi, among them, Beauveria bassiana is the most studied species. However, there are few knowledge regarding their antimicrobial activity. The current research has been conducted to evaluate in vitro antagonistic activity of B. bassiana and the antimicrobial efficacy of its Exo and Endo metabolites against Bacillus cereus, B. megaterium, Clavibacter michiganensis (gram positive bacteria, G+ve), Xanthomonas campestris, Pseudomonas aeruginosa and P. fluorescence (gram negative bacteria, G-ve). In addition, Solid-phase microextraction (SPME) was coupled to Gas Chromatography-Mass Spectrometry (GC/MS) to qualitatively measure the volatile organic compounds (VOCs) metabolic profile of the most efficient studied isolate of B. bassiana. The obtained results showed that, the isolate UniB2439-3 has promising antibacterial effect against most of studied target bacteria. SPME-GC/MS analysis of VOCs revealed the presence of ethanol; butanal,2-methyl; 2,4-dimethyl-1-heptene; octane, 4-methyl and β-elemene as the main dominant bioactive compounds. The outgoing results explicated that the efficient isolate of B. bassiana can be potentially used as a biocontrol agent against several bacteria especially G+ve ones.
... importance of B. bassiana in reducing a range of nuisance insects, where it can induce direct insect mortality [2,13,14] and can also reach 90% reduction of life-time fecundity [15]. ...
... Genus Beauveria include entomopathogenic and endophytic fungi which are widely spread in different habitats [1][2][3]. Furthermore, many researchers reported that fungi in the genus Beauveria can produce enzymes for biotransformation and biodestructors [4,5]. On the other hand, the genus Beauveria is considered also a human pathogen where it causes opportunistic infections especially in patients with weak immune systems [6]. ...
Full-text available
The genus Beauveria include important entomopathogenic and endophytic fungi, among them, B. bassiana is the most studied species. However, there are few knowledge regarding their antimicrobial activity. The current research has been conducted to evaluate in vitro antibacterial efficacy of five isolates of B. bassiana against Bacillus cereus, B. megaterium, B. mojavensis, Clavibacter michiganensis (gram positive bacteria, G+ve), Xanthomonas campestris, X. vesicatoria, Escherichia coli, Pseudomonas aeruginosa and P. fluorescence (gram negative bacteria, G-ve). In addition, chemical composition of the principal diffusible metabolites and volatile organic compounds (VOCs) of the most efficient studied isolate of B. bassiana has been carried out using GC-MS analysis. The obtained results showed that, the isolate UniB2439-3 has promising antibacterial effect against most of studied target bacteria. GC-MS analysis of diffusible metabolites detected the presence of hexanedioic acid, bis(2-ethylhexyl) ester as the main compound in the cell-free culture filtrate. Furthermore, GC-MS analysis of VOCs revealed the presence of ethanol; butanal,2-methyl; 2,4-dimethyl-1-heptene; octane, 4-methyl and β-elemene as the main dominant bioactive compounds. The outgoing results explicated that, the isolates of B. bassiana have promising antibacterial activity which could be correlated to their diffusible and VOCs metabolites. Therefore, the selected isolate can be potentially used as a biocontrol agent against several bacteria especially G+ve ones. Taking in consideration that the antibiotics are forbidden in agriculture in many countries worldwide, search for possible natural alternatives as efficient antimicrobial agents are highly interesting.
... and Metarhizium anisopliae (Metschn.)] have been tested against C. lectularius (1,11,135). Metarhizium anisopliae was only effective at very high humidities (133). ...
... Metarhizium anisopliae was only effective at very high humidities (133). In contrast, B. bassiana performed well at 50% relative humidity (11), leading to the commercialization of a B. bassiana-based liquid spray formulation. The fungal-based formulation was effective against both susceptible and pyrethroidresistant C. lectularius (10) and when combined with other insecticides (120,121). ...
Bed bugs (Hemiptera: Cimicidae) are an important group of obligate hematophagous urban insect pests. The global resurgence of bed bugs, involving the common bed bug, Cimex lectularius L., and the tropical bed bug, Cimex hemipterus (F.), over the past two decades is believed to be primarily due to the development of insecticide resistance, along with global travel and poor pest management, which have contributed to their spread. This review examines and synthesizes the literature on bed bug origins and their global spread and the literature on historical and contemporary control options. This includes bed bug prevention, detection and monitoring, nonchemical and chemical control methodologies (and their limitations), and potential future control options. Future research needs are highlighted, especially the factors behind the modern resurgence, the necessity of identifying differences between the two bed bug species relevant to control, and the need to improve insecticide test protocols and management strategies. Expected final online publication date for the Annual Review of Entomology, Volume 68 is January 2023. Please see for revised estimates.
... 61 Figure 5 includes other chemicals and biological methods, such as fungal agents and other agents that can sterilize the bugs. [62][63][64] Figure 2 (a) Cimex lectularius. (b) Life cycle of bedbugs, triangles demonstrating the change in appearance after a feed. ...
Bed bugs are on the rise in urban populations across the world, perhaps reflecting the ban on the use of organophosphates in many countries worldwide. They are flat obligate haematophagous insects, preferring humans, and as a consequence the bed bug bites lack toxins and can often go unnoticed for some time. Bites can however cause wheals, purpura, petechiae, vesicles, pustules, papular urticaria, localised infection and rarely anaphylaxis. Infestations have to be confirmed by finding the bugs, usually around the bed of the person being bitten. Eradication usually requires a combination of physical (e.g.high temperature, mattresses protectors, traps, cold) and chemical methods (e.g. chrysanthemic acid derivatives plus potentiators such as geraniol and piperonyl butoxide, or acetyl choline esterase inhibitors).
... This product was found to be effective for both insecticide-resistant strains of Cimex lectularius L. (>94% mortality) and a susceptible strain (98-100% mortality) (Barbarin et al. 2017). Beauveria bassiana was also found to be highly virulent to both adult and nymphal stages of C. lectularius, usually resulting in 100% mortality by three to five days postexposure, and can be transferred horizontally among conspecifics from treated to untreated bed bugs within harborage sites (Barbarin et al. 2012, Aak et al. 2018. Shikano et al. (2021) found that the residues of a majority of 22 insecticides used for bed bug control resulted in reduced spore viability when Aprehend was applied to the surface. ...
The use of the entomopathogenic fungus Beauveria bassiana (Bals. – Criv.) Vuill. (Hypocreales: Cordycipitaceae) has been recently incorporated in the management of bed bugs, Cimex lectularius L. (Hemiptera: Cimicidae). Bed bugs produce a set of aldehydes that are known to affect the growth of some fungi. Considering that bed bugs or their exuviae release these aldehydes, it was suspected that the bed bugs’ aggregation sites would contain an increased level of the bed bug aldehydes. The current study examined if elevated levels of the bed bug aldehydes in the microhabitats would impact the efficacy of B. bassiana. Following a brief exposure to the residues of commercial products containing B. bassiana, the treated bed bugs were kept in a vial with or without a natural or artificial blend of bed bug aldehydes (i.e., exuviae or synthetic compounds). For a B. bassiana product that is not currently registered for bed bugs control, the presence of aldehydes significantly reduced 15-d mortality (61–62%) compared to the no aldehydes control (97.7%). However, when tested with a B. bassiana formulation designed for bed bug control, the aldehydes only caused delayed mortality for the treated bed bugs. When tested in culture, the growth rate of B. bassiana on a medium was significantly reduced when the bed bug aldehydes were provided in the headspace. Implications on practical bed bug management using fungal biopesticides are discussed.
... Although some modes of exposure were more effective than others, we found that, overall, the bed bugs were susceptible to B. bassiana through all the tested routes of exposure. These findings are consistent with previous research using contact assays with the same B. bassiana strain [18][19][20]. On the other hand, the German cockroaches were largely unaffected by B. bassiana, except when conidia were introduced directly into the hemocoel by injection or when exposed to dry aerial conidia that were not sprayed in a liquid suspension. ...
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The ability of a fungal entomopathogen to infect an insect depends on a variety of factors, including strain, host, and environmental conditions. Similarly, an insect’s ability to prevent fungal infection is dependent on its biology, environment, and evolutionary history. Synanthropic pests have adapted to thrive in the indoor environment, yet they arose from divergent evolutionary lineages and occupy different feeding guilds. The hematophagous bed bug (Cimex lectularius) and omnivorous German cockroach (Blattella germanica) are highly successful indoors, but have evolved different physiological and behavioral adaptations to cope with the human-built environment, some of which also reduce the efficacy of fungal biopesticides. In order to gain greater insight into the host barriers that prevent or constrain fungal infection in bed bugs and German cockroaches, we tested different doses of Beauveria bassiana GHA through surface contact, topical application, feeding, and injection. Bed bugs were generally more susceptible to infection by B. bassiana with the mode of delivery having a significant impact on infectivity. The German cockroach was highly resilient to infection, requiring high doses of fungal conidia (> 8.8 × 104) delivered by injection into the hemocoel to cause mortality. Mortality occurred much faster in both insect species after exposure to surfaces dusted with dry conidia than surfaces treated with conidia suspended in water or oil. These findings highlight the importance of developing innovative delivery techniques to enhance fungal entomopathogens against bed bugs and cockroaches.
... As a saprotrophic fungus, Spizellomyces colonizes decaying plant material that seems to be provided by the nearby plants, while Pseudogymnoascus destructans was proven to live in wood or soil and can cause white-nose syndrome (WNS) in bats [76]. In addition, Sphaerobolus stellatus is known as the shotgun or artillery fungus because it discharges its spores with explosive forces, while Beauveria bassiana grows naturally in the soil and acts as a parasite and biological insecticide to control several pests [77]. None of the latter four taxa seems to have any justified response to either soil type or watering time point. ...
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The metagenomic whole genome shotgun sequencing (mWGS) approach was used to detect signatures of the rhizosphere microbiomes of Dipterygium glaucum and surrounding bulk soil microbiomes, and to detect differential microbial responses due to watering. Preliminary results reflect the reliability of the experiment and the rationality of grouping microbiomes. Based on the abundance of non-redundant genes, bacterial genomes showed the highest level, followed by Archaeal and Eukaryotic genomes, then, the least abundant viruses. Overall results indicate that most members of bacteria have a higher abundance/relative abundance (AB/RA) pattern in the rhizosphere towards plant growth promotion, while members of eukaryota have a higher pattern in bulk soil, most likely acting as pathogens. The results also indicate the contribution of mycorrhiza (genus Rhizophagus) in mediating complex mutualistic associations between soil microbes (either beneficial or harmful) and plant roots. Some of these symbiotic relationships involve microbes of different domains responding differentially to plant root exudates. Among these are included the bacterial genus Burkholderia and eukaryotic genus Trichoderma, which have antagonistic activities against the eukaryotic genus Fusarium. Another example involves Ochrobactrum phage POA1180, its bacterial host and plant roots. One of the major challenges in plant nutrition involves other microbes that manipulate nitrogen levels in the soil. Among these are the microbes that perform contraversal actions of nitrogen fixation (the methanogen Euryarchaeota) and ammonia oxidation (Crenarchaeota). The net nitrogen level in the soil is originally based on the AB/RA of these microbes and partially on the environmental condition. Watering seems to influence the AB/RA of a large number of soil microbes, where drought-sensitive microbes (members of phyla Acidobacteria and Gemmatimonadetes) showed an increased AB/RA pattern after watering, while others (Burkholderia and Trichoderma) seem to be among microbes assisting plants to withstand abiotic stresses. This study sheds light on the efficient use of mWGS in the taxonomic assignment of soil microbes and in their response to watering. It also provides new avenues for improving biotic and abiotic resistance in domestic plant germplasm via the manipulation of soil microbes.
... Using this spray application equipment and the proprietary oil formulation of B. bassiana spores in Aprehend, we were able to demonstrate excellent efficacy against bed bugs following brief exposure to spray residues 7 weeks after application (Shikano et al 2021). Furthermore, following contact with the spray residue, bed bugs return to their harborages providing additional efficacy via autodissemination of the spores (Barbarin et al. 2012). We also verified that Aprehend was equally effective against insecticide resistant and non-resistant bed bug strains (Barbarin et al. 2017). ...
Conference Paper
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The Sixth International Symposium on Biological Control of Arthropods, held virtually from British Columbia, Canada, continues the series of International Symposia on Biological Control of Arthropods, organized every four years. The history of the meetings is: • First ISBCA, Hawaii, USA – January 2002 • Second ISBCA, Davos, Switzerland – September 2005 • Third ISBCA, Christchurch, New Zealand – February 2009 • Fourth ISBCA: Pucón, Chile – March 2013 • Fifth ISBCA: Langkawi, Malaysia – September 2017 The goal of these symposia is to create a forum where biological control researchers and practitioners can meet and exchange information, to promote discussions of up to date issues affecting biological control, particularly pertaining the use of parasitoids and predators as biological control agents. This includes all approaches to biological control: conservation, augmentation, and importation of natural enemy species for the control of arthropod targets, as well as other transversal issues related to its implementation. To this end, 12 sessions have been organized in order to address the most relevant and current topics in the field of biological control of arthropods, delivered by invited speakers, contributed talks and poster presentations. To kick off ISBCA 2022, Dr. Martin Hill, Global President of the International Organization for Biological Control, presents an opening keynote talk on the current state of biological control. Some of the topics covered in ISBCA 2022 have remained as important issues since the first meeting, like the importance of biological control for managing invasive species, sustainable pest regulation in agricultural landscapes, the continuing challenges for biological control of forest pests, and the role of native vegetation in conservation biological control. But also, as new challenges and environmental concerns arise, some fresh topics have emerged. Among them are climate change and the disruption of biological control, stakeholder knowledge and perceptions of biological control, the use of native and exotic natural enemies for augmentative biological control, and functional diversity supporting biological control. For the first time, a workshop on biological control of ticks will be held. To show that biological control is a continuum linked to other disciplines, there will be a session on the science underpinning the successful use of pathogens in biological control. An important goal of the International Symposium on Biological Control of Arthropods is to promote early career researchers, and the first session Proceedings of ISBCA 6 – D.C. Weber, T.D. Gariepy, and W.R. Morrison III, eds. (2022) iii is organized to showcase the work of select individuals. The International Organization for Biological Control (IOBC) has sponsored these presentations. Another important goal of these meetings has been to be truly international, and this is why every conference so far has been organized in a different continent. This year we are excited in having achieved this goal despite the many world crises, by having participants from over 30 countries and all continents except Antarctica. We are particularly happy for the many works and participants from South America, a region that in the past has been poorly represented in these symposia. As a result, this meeting represents an opportunity for creating and expanding networks between researchers worldwide. Thus we expect that, despite the virtual format, the 6th International Symposium on Biological Control of Arthropods would be an important milestone in keep moving forward the research and practice on biological control of arthropods, thereby helping to improve the sustainability of managed systems as well as aiding in the protection of biodiversity on the planet.
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Post-mating immunosuppression has been widely accepted as a female trait in Drosophila melanogaster . Our results challenge this notion by presenting a mating-immunity trade-off in males as well as in females. When inoculated with the fungal pathogen, Beauveria bassiana , both males and females die faster compared to inoculated virgins, and survival is lower when inoculated flies are continuously mated compared to a single day of mating. Past studies with Beauveria bassiana have shown females to be more susceptible to infection than males. Our results challenge this finding as well, showing that the direction of sexual dimorphism in immune defense depends on mating status, specific Beauveria bassiana strain, and fly genotype. Moreover, we show that survival after fungal infection is largely influenced by diet, and that post-infection dietary improvements can help enhance survival. Post-mating suppression in Drosophila survival of B. bassiana infection presents study opportunities with potential applications for biological control of insect vectors of human disease and insect crop pests.
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Dengue is a global health concern. Growing insecticide resistance in the primary mosquito vector, Aedes aegypti, limits the effectiveness of vector control, so alternative tools are urgently needed. One approach is the use of biopesticides comprising entomopathogenic fungi, e.g. Beauveria bassiana and Metarhizium anisopliae. These fungi may decrease disease transmission by reducing mosquito vector longevity and also occur worldwide, although many isolates have not been tested for virulence against mosquitoes. Ninety-three isolates of entomopathogenic fungi representing 6 species (B. bassiana, M. anisopliae, Isaria fumosorosea, I. farinosa, I. flavovirescens and Lecanicillium spp.) were screened as potential biological control agents of Aedes aegypti. A hierarchical, multi-criteria experimental design was undertaken to find suitable isolates. Initial screening was performed via in vitro assays measuring radial growth and spore persistence, eliminating isolates with poor growth or viability on nutrient-rich substrate. Subsequent measurements of spore persistence revealed that only 9 of 30 strains tested had half-lives exceeding 3 weeks. Ten isolates were chosen for in vivo bioassays against adult Ae. aegypti. From these assays, two Australian isolates of B. bassiana, FI-277 and FI-278, appeared to be most promising. Both isolates were shown to be virulent against Ae. aegypti at 20, 26 and 32°C. Spreading spores manually onto substrate was found to be more efficacious than spraying. Ae. aegypti infected by manually-spread spores on cotton substrate were found to have an LT50 of 3.7±0.3 d. These characteristics suggest that FI-277 has promise as a dengue mosquito biocontrol agent, either alone or combined with conventional chemical insecticides.
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Prior to the global outbreak of Bemisia tabaci type B in the early 1990s, very little attention was paid to the potential of fungal pathogens for control of this whitefly. A massive foreign exploration effort was mounted in 1991 by the USDA Agricultural Research Service to collect and develop fungi and other natural enemies of whiteflies. From 1990 until 1996, dozens of trips were made by scientists from the USDA European Biological Control Laboratory (EBCL) in Montpellier, France specifically for the purpose of finding natural enemies of whiteflies. The countries visited by EBCL ranged from European countries bordering the Mediterranean (Spain, France, Italy, Greece, Cyprus), to the Middle East (Israel, Egypt), Western Asia (Pakistan, India, Nepal), Southeast Asia (Thailand, Malaysia) and Latin America (Argentina and Brazil). Other exploratory efforts for entomopathogenic fungi within the USA and in other foreign countries (Philippines, Indonesia, Taiwan) were also undertaken by USDA-ARS personnel in Weslaco, Texas. The most prevalent fungus attacking B. tabaci in the field was Paecilomyces fumosoroseus. Fungi from whiteflies or from other insects with good activity against the silverleaf whitefly include Paecilomyces spp., Lecanicillium lecanii (=Verticillium), Beauveria bassiana and Aschersonia spp. Hundreds of isolates of these fungi were collected and shipped to the USA. Subsequent research involved screening of isolates for activity, study of factors that limited or enhanced their activity, and evaluation of candidate fungi in field and glasshouse crops. The literature on research for the development and implementation of these fungi is reviewed with recommendations for future avenues of research and development.
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Rapidly emerging insecticide resistance is creating an urgent need for new active ingredients to control the adult mosquitoes that vector malaria. Biopesticides based on the spores of entomopathogenic fungi have shown considerable promise by causing very substantial mortality within 7-14 days of exposure. This mortality will generate excellent malaria control if there is a high likelihood that mosquitoes contact fungi early in their adult lives. However, where contact rates are lower, as might result from poor pesticide coverage, some mosquitoes will contact fungi one or more feeding cycles after they acquire malaria, and so risk transmitting malaria before the fungus kills them. Critics have argued that 'slow acting' fungal biopesticides are, therefore, incapable of delivering malaria control in real-world contexts. Here, utilizing standard WHO laboratory protocols, we demonstrate effective action of a biopesticide much faster than previously reported. Specifically, we show that transient exposure to clay tiles sprayed with a candidate biopesticide comprising spores of a natural isolate of Beauveria bassiana, could reduce malaria transmission potential to zero within a feeding cycle. The effect resulted from a combination of high mortality and rapid fungal-induced reduction in feeding and flight capacity. Additionally, multiple insecticide-resistant lines from three key African malaria vector species were completely susceptible to fungus. Thus, fungal biopesticides can block transmission on a par with chemical insecticides, and can achieve this where chemical insecticides have little impact. These results support broadening the current vector control paradigm beyond fast-acting chemical toxins.
Persistent chemical pesticides can provide an effective means of control against locusts and grasshoppers due to prolonged activity of the spray residue. However, use of these pesticides is now prohibited, and non-persistent chemical alternatives are substantially less successful. Here we show why it is expected that biological pesticides based on the fungal pathogen Metarhizium flavoviride will be highly effective in the control of both locust and grasshopper. We demonstrate, using novel population dynamic models containing measured estimates of horizontal transmission coefficients, that secondary cycling of the pathogen after a single spray application provides a biological substitute for chemical persistence. This has significant consequences for the economics of biopesticide use in pest control. Furthermore, by identifying that secondary cycling acts in a density-dependent manner, this study also highlights fundamental differences between conventional pesticides and biopesticides and how they might be used.
Some marked bugs were released and the proportion of recaptures to others in the total catch was noted. From this a rough estimate of the population was made. It appears that few adults live more than 29 days as they are probably killed by the rats when trying to feed.(Received January 11 1939)
Laboratory studies were carried out to determine the effect of sex and age on the susceptibility of tsetse, Glossina morsitans morsitans and G. m. centralis, to the entomopathogenic fungus, Metarhizium anisopliae. Both species of host flies were susceptible to fungal infection. Female flies were generally more susceptible than male flies. Three host ages (40, 20, and <1 day-old) were used; the youngest group was most resistant to fungal infection. Interactions between species, sex and age were significant on many occasions. Age usually accounted for the largest variability in mortality, followed by sex. All flies of age 40 days died between 7 and 8 days after infection whereas some of the younger flies, especially age 0, lived longer than 10 days. Log10 day probit (LDP) mortality regressions fitted well to most of the data sets. LDP slopes were significant and high, ranging between 4.3 and 12.8, indicating a generally high mortality rate of increase over days. The slopes differed significantly between species, sexes, and ages, but grouping by age was more intra homogeneous than by species or sex. The 50% lethal time mortalities (LT50) ranged between 4 and 7 days for age 0, 3 and 6 days for age 20, and about 5 days for age 40. Corresponding ranges of the LT95 were 8 to 20, 5 to 10, and 6 to 7 days for ages 0, 20 and 40, respectively. The significance of these results in the fungal disease transmission by tsetse is discussed.
Studies were conducted with two different doses of Metarhizium anisopliae var acridum to examine the effects on survival and reproductive potential of adult Schistocerca gregaria under conditions that either limited thermoregulation or enabled optimal thermoregulation. Adult S. gregaria infected with the fungal pathogen showed either a rapid and high mortality at relatively constant temperatures or a much reduced mortality and lengthened survival time when allowed to thermoregulate. Mortality rate varied from >90% after 10 days under constant temperature conditions to 66% after 70 days under optimal thermoregulatory conditions. Effects of infection on maturation and reproduction depended on the age of the adults at the time of inoculation, the nighttime temperature regime, the fungal dose, and the length of time of the monitoring period. No difference in reproductive behaviors in treated and control insects were found in one experiment that utilized older adults and was conducted over 25 days. In a second experiment with newly fledged locusts, differences in maturation rates and total reproductive output were observed due to infection. The results from these experiments are discussed in terms of the potential of M. anisopliae var acridum to alter the balance of insect endocrine systems and the importance of the assessment of behavioral changes and their impact on microbial control agents in the long term.