Biological control of Cimex lectularius with Beauveria bassiana: Effects of substrate,dosage, application strategy,and bed bug physiology

Background

Cimex lectularius L. (bed bug) (Hemiptera: Cimicidae) is a serious indoor pest worldwide, and this nuisance needs to be controlled using different methods in integrated pest management (IPM). Beauveria bassiana (Bals.-Criv.) Vuill. (Hypocreales: Cordycipitaceae) kills bed bugs, and insect pathogenic fungi may be utilized to control bed bugs in IPM. To increase knowledge of this methodology, forced exposure experiments were conducted with different formulations, doses, and substrates, using bed bugs in variable physiological states.

Results

Both oil- and water-formulated fungal products showed significant improvement when conidial concentrations were raised in five steps from 0.02 to 2.0%. At low concentrations (0.02% in water) effects from substrate and application strategy were observed. Application on soft substrates (cotton and polyester) yielded significantly higher bed bug mortality rates than on harder substrates (paper, wood, and linoleum) with a final mortality of 35–63% against 8–10%. Multiple applications over time also improved B. bassiana's ability to kill bed bugs, and at low concentrations only a triple application on cotton showed 100% final mortality. Bed bug age and reproductive status significantly affected survival. Older and reproducing individuals showed higher mortality compared to newly emerged adults. Differences in feeding status also yielded differences in mortality timing, but only minor differences in final mortality rates. Egg production and hatching success were significantly reduced by some treatments.

Conclusion

B. bassiana appears to be an asset in the fight against bed bugs. Substrate, dosage, application strategy, and bed bug physiology are important factors to consider for optimal efficacy and safe indoor control with insect pathogenic fungi. © 2023 Society of Chemical Industry.     

Stage-specific action of juvenile hormone analogs

The discovery of juvenile hormones (JH) and their synthetic analogs (JHA) generated excitement and hope that these compounds will replace first- and second-generation insecticides that have not so desirable environmental and human safety profiles. However, JHAs used commercially during the past four decades did not meet these expectations. The recent availability of advanced molecular and histological methods and the discovery of key players involved in JH action provided some insights into the functioning of JHA in a stage and species-specific manner. In this review, we will summarize recent findings and stage-specific action of JHA, focusing on three commercially used JHA, methoprene, hydroprene and pyriproxyfen and economically important pests, the red flour beetle, Tribolium castaneum, and the tobacco budworm, Heliothis virescens, and disease vector, the yellow fever mosquito, Aedes aegypti.     

Investigations on Oecophylla longinoda (Latreille) (Hymenoptera: Formicidae) as a biocontrol agent in the protection of cashew plantations

BACKGROUND: Cashew (Anacardium occidentale L.) has become a very important non‐traditional tree crop in Ghana. The crop is, however, attacked by sap‐sucking insects, particularly the mosquito bug, Helopeltis schoutedeni Reuter, the leaf‐footed bug, Pseudotheraptus devastans (Dist.), and the coreid bug, Anoplocnemis curvipes (F.), which feed on shoots, panicles and fruits. Their damage is characterised by withering of the latter. In Ghana, Oecophylla longinoda Latr. occurs in large numbers on cashew and other native plants, but little is known about its relationship with insect pests. The relationship between O. longinoda and shoot and panicle damage by sap‐sucking bugs and the effectiveness of O. longinoda as a biocontrol agent in the protection of cashew as compared with two chemical insecticides, lambda‐cyhalothrin (Karate^®) and cypermethrin + dimethoate (Cyperdim^®), were therefore investigated at Bole in the northern region of Ghana. RESULTS: There was a negative correlation between numbers of O. longinoda nests and pest damage. Trees treated with cypermethrin + dimethoate (969 mg AI mL^?1 tree^?1) and lambda‐cyhalothrin (100 mg AI mL^?1 tree^?1) recorded the smallest bug numbers, followed by O. longinoda. Trees infested by Oecophylla longinoda and trees treated with cypermethrin + dimethoate and with lambda‐cyhalothrin had less than 6% pest damage to shoots, panicles and fruits, while water‐sprayed trees recorded damage as high as 36.8% (shoots) in February, 32.9% (panicles) in February and 37.8% (fruits) in March. Cypermethrin + dimethoate again recorded the highest (485.0 kg ha^?1) nut yield, followed by O. longinoda (431.0 kg ha^?1), with water recording the lowest (93.0 kg ha^?1) nut yield. CONCLUSION: The results indicate that O. longinoda can be used to control some sucking bugs as effectively as some insecticides. Copyright © 2008 Society of Chemical Industry     

Semiochemicals of the common bed bug,Cimex lectularius L. (Hemiptera: Cimicidae), and their potential for use in monitoring and control

The recent resurgence of the common bed bug, Cimex lectularius L., has driven an increase in research into the biology and behaviour of this pest. Current control is reliant on the application of insecticides, but, owing to the development of insecticide resistance, there is a need for new tools and techniques. Semiochemicals (behaviour‐ and physiology‐modifying chemicals) could be exploited for management of bed bugs. The aim of this review was to evaluate studies undertaken in bed bug chemical ecology to date, with particular reference to how the research could be exploited for monitoring and control. Bed bugs, like many other insects, have a complex olfactory system. Recent studies have characterised the olfactory sensilla, located on the terminal segment of the antennae, to functional classes by electrophysiological screening. Behavioural studies have revealed the presence of an alarm pheromone and potential airborne aggregation semiochemicals, but it is not yet understood if bed bugs use a sex pheromone during mating. Host location cues have been investigated, and carbon dioxide has been found to be highly attractive both in laboratory and in field studies. Recent field trials have tested blends of other potential kairomones, which have been shown to have an additive effect when used in a heated bed bug trap with carbon dioxide. The trap, which combines heat and kairomones, is the only trap currently available with proven efficacy in the field. In order for semiochemicals to be useful for bed bug management, an increased knowledge and understanding of the biology, behaviour and chemical ecology of this insect is essential. Copyright © 2010 Society of Chemical Industry     

Using research and education to implement practical bed bug control programs in multifamily housing

Multifamily housing facilities serving low‐income populations have been at the forefront of bed bug outbreaks. Research conducted in the past 8 years has consistently proven that integrated pest management (IPM) is the best approach for successful suppression of bed bug infestations. Bed bug IPM in multifamily settings is especially dependent upon a collaborative community or building‐wide effort involving residents, building staff and pest control technicians. Other components of a bed bug IPM program include regular monitoring to detect early‐stage bed bug infestations and combined use of non‐chemical and chemical interventions. Lastly, to reduce reinfestation rates and costs associated with bed bug control, it is critical to continue periodic monitoring and implement preventive control measures even after successful elimination of bed bugs has been achieved. © 2015 Society of Chemical Industry     

Effect of methoprene on the progeny production of Tribolium castaneum (Coleoptera: Tenebrionidae)

BACKGROUND: Tribolium castaneum (red flour beetle) is a serious insect pest of stored products around the world. Current control measures for this species have several limitations: loss of registration of insecticides, insecticide resistance and consumer concerns about chemical residues in food. The objective of this study was to determine whether methoprene affects progeny production of T. castaneum. Late‐instar larvae or young adults were exposed to methoprene‐treated wheat, and progeny production was determined. The pairing of male and female adults was performed as untreated × untreated, treated × untreated or treated × treated, to study sex‐based effects. RESULTS: There were three outcomes to late‐instar larvae held on methoprene‐treated wheat kernels (0.001 and 0.0165 ppm): (1) failure to emerge as an adult; (2) emergence as an adult, and almost no offspring produced; (3) emergence as an adult and normal production of offspring. Male larvae were more susceptible to methoprene than female larvae. In contrast, young adults exposed to methoprene (1.67–66.6 ppm) showed no reduction in offspring production. CONCLUSION: Methoprene concentrations will decline with time following its application. However, this research indicates that methoprene can still reduce populations of T. castaneum by reducing their progeny production, even if adults emerge. Copyright © 2011 Society of Chemical Industry     

Virulence of select entomopathogenic fungi to the brown marmorated stink bug, Halyomorpha halys (Stål) (Heteroptera: Pentatomidae)

The brown marmorated stink bug. Halyomorpha halys, (BMSB) is an exotic pest causing damage to fruits and vegetables. They also transmit diseases. Integrated pest management strategies are lacking for this invasive. For the first time, information is presented on the virulence of several entomopathogenic fungi against BMSB. Three Beauveria bassiana and two Metarhizium anispoliae isolates were bioassayed against adult BMSB. One B. bassiana isolate was the active ingredient in BotaniGard^® which produced 85 and 100% mortality in 9 and 12 days post treatment, respectively. Experimental isolates ERL 1170 and ERL 1540 were also efficacious. Metarhizium anispoliae isolates produced lower mortalities than the B. bassiana isolates. Data presented showed the potential for management of BMSB with entomopathogenic fungi. Copyright © 2012 Society of Chemical Industry     

Surface contact toxicity and synergism of several insecticides against different stages of the tropical bed bug, Cimex hemipterus (Hemiptera: Cimicidae)

BACKGROUND: Five formulated insecticides (lambda‐cyhalothrin at 10 mg m^?2, bifenthrin at 50 mg m^?2, fipronil at 10 mg m^?2, fenitrothion at 50 mg m^?2, imidacloprid at 5 mg m^?2) and one active ingredient (DDT at 500 mg m^?2) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda‐cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed. RESULTS: The order of susceptibility of different stages of bed bugs was as follows: early stage ? lambda‐cyhalothrin > bifenthrin = imidacloprid > fipronil > fenitrothion > DDT; late stage—lambda‐cyhalothrin > bifenthrin > fenitrothion > imidacloprid > fipronil > DDT; adult—lambda‐cyhalothrin > imidacloprid > bifenthrin > fenitrothion > fipronil > DDT. The late instars exhibited significantly higher LT₅₀ among the life stages. The addition of PBO to fipronil increased the susceptibility of the insects. CONCLUSIONS: Lambda‐cyhalothrin, bifenthrin, fenitrothion and fipronil at the recommended application rates were effective against C. hemipterus. Although imidacloprid demonstrated good initial response against C. hemipterus, the insects showed substantial recovery 72 h post‐treatment. The late instars (fourth and fifth instars) should be used as the model for toxicological evaluation. Copyright © 2011 Society of Chemical Industry     

Evaluation of chlorfenapyr for control of the bed bug,Cimex lectularius L.

BACKGROUND: The presence of bed bug populations resistant to pyrethroids demands the development of new control tactics, including the use of insecticides with new modes of action. Insecticides that disrupt oxidative phosphorylation in insect mitochondria can be an option. Laboratory assays were used to measure the toxicity of chlorfenapyr to susceptible strains and two strains highly resistant to pyrethroids. The effectiveness of two chlorfenapyr‐based formulations was compared, and behavioral responses of bed bugs to dry residues of aerosol sprays were evaluated. RESULTS: Chlorfenapyr was effective against all bed bug strains, killing them at a similar rate, regardless of their susceptibility status to pyrethroids. Dry residues aged for 4 months were as toxic as fresh dry residues. The aerosol formulation had contact activity and caused faster mortality than a water‐based formulation. Bed bugs did not avoid resting on surfaces treated with aerosol. CONCLUSION: Chlorfenapyr is an option for controlling pyrethroid‐resistant bed bugs. While it does not cause quick knockdown, its long residual activity and no avoidance behavior of bed bugs to dry residues appear to make this insecticide suitable for bed bug control. A faster insecticidal effect is obtained with the aerosol formulation, suggesting greater bioavailablity of the toxicant. Copyright © 2010 Society of Chemical Industry     

Use of novel approaches for designing safer drugs in insecticide research: Soft alkylating agents

Based on the analogy between anticancer drugs and insect chemosterliants, both of them acting by virtue of their alkylating capacity, chloromethyl carboxylates (described by Bodor and co-workers as potential anticancer drugs of the soft alkylating agent type) including the chloromethyl ester analogues of the juvenoids hydroprene and methoprene were prepared and tested for chemosterilant and morphogenetic juvenile hormone activity. While the chloromethyl esters of some simple carboxylic acids were inactive in this respect, the juvenoid chloromethyl esters revealed both chemosterilant and morphogenetic activity against Dysdercus cingulatus comparable with that of the known juvenoids hydroprene and methoprene. At the same time their activity against Pieris brassicae showed a sharp drop compared to the ‘parent’ compounds. The results suggest a species-dependent rate of enzymatic hydrolysis of the chloromethyl ester group as a possible reason for their selective action. Thus, the chloromethyl ester group might function as a ‘selectivity factor’).     

Comparative testing of several juvenile hormone analogues in two species of locusts,Locusta migratoria migratorioides and Schistocerca gregaria

Effective treatment with juvenile hormone analogues (JHAs) of early penultimate or early last-instar locust hoppers induces a supernumerary ‘extra’ nymphal instar. These ‘extra’ nymphs, also termed ‘adultoids’, die in the course of, or shortly after, an ‘extra’ moult. Less effective treatment results in imperfect adults with crumpled twisted wings which presumably limit their flight and migratory abilities. Extremely effective treatment leads to death in the next moult. Comparing dose-response relations of (7S)-methoprene, fenoxycarb, pyriproxyfen and a new JHA, R70-1 (ethyl cis-N-{2-[4-(2-hydroxycyclohept-1-ylmethyl)phenoxy]ethyl}carbamate), we revealed that route of administration, instar of the recipient hopper, and species may alter over 1000-fold the ED₅₀ for the same JHA. Locusta migratoria migratorioides is much more susceptible to JHAs than Schistocerca gregaria. The lowest ED₅₀ found to induce adultoids and subsequent death in the ‘extra’ moult was 0·12 μg pyriproxyfen injected in olive oil to early penultimate instar hoppers of L. m. migratorioides (about 0·5 μg g^-1 fresh weight). R70-1 was more active than pyriproxyfen following the more practical topical application to early last-instar hoppers of L. m. migratorioides, 5·9 μg and 46 μg per hopper, respectively (about 10 μg g^-1 and 78 μg g^-1 fresh weight). The high susceptibility of last-instar L. m. migratorioides nymphs to topically applied R70-1 is promising from the practical standpoint. ©1997 SCI     

Inhibitory effects of some insect growth regulators on developmental stages,fecundity and fertility of the Florida wax scale,Ceroplastes floridensis

Four juvenile hormone analogs (JHAs), fenoxycarb. Pro-drone, R-20458 and dofenapyn, and three benzoylphenyl urea molt-inhibiting compounds (MICs), teflubenzuron, triflumuron and hexaflumuron, were evaluated in the laboratory at two concentrations (5 and 50 ppm) as to their effect on the Florida wax scale,Ceroplastes floridensis Comstock. In general, when the first nymphal stages were treated, the number of adults on treated guava plants at the end of the first generation was clearly reduced in comparison with that observed on untreated plants. The JHAs fenoxycarb and R-20458 arrested the development of the insect and no adults emerged at the end of the first generation. With 50 ppm of the JHA Pro-drone only 5.2% of the nymphs developed and transformed into adults. Triflumuron was superior to the other insect MICs in hampering development, as was dofenapyn. The adults emerging at the end of the first generation were used as parental scales for the next generation. Delayed adverse effects were observed on female fecundity and egg hatchability. There was a significant difference between the egg numbers laid by the females in the treatments and the control, and also between the different IGRs. No eggs hatched with dofenapyn and egg hatchability was 46% for teflubenzuronvs 88% for the control. Furthermore, in contradistinction to the control, insects on treated plants deposited only small amounts of wax in an irregular formation.     

High level methoprene resistance in the mosquito Ochlerotatus nigromaculis (Ludlow) in central California

In the summer of 1998, failures of methoprene field applications to control the mosquito Ochlerotatus nigromaculis (Ludlow) were noticed in several pastures in the outskirts of Fresno, California, USA. Effective control with methoprene had been achieved for over 20 years prior to this discovery. Susceptibility tests indicated that the Fresno Oc nigromaculis populations had developed several thousand‐fold higher LC₅₀ and LC₉₀ tolerance levels to methoprene compared with methoprene‐naïve populations. The synergists piperonyl butoxide (PBO), S,S,S‐tributyl phosphorotrithioate and 3‐octylthio‐1,1,1‐trifluoro‐2‐propanone had little synergistic effect, suggesting that the mechanism of methoprene tolerance was not mediated by P450 monooxygenase or carboxylesterase enzyme degradation. As part of initiating a resistance management strategy, partial reversion back to methoprene susceptibility was achieved in a resistant population after six consecutive applications of Bacillus thuringiensis israelensis Goldberg & Marga coupled with two oil and two pyrethrum + PBO applications. © 2002 Society of Chemical Industry     

Evaluation of organically acceptable insecticides as stand-alone treatments and in rotation for managing yellowmargined leaf beetle, Microtheca ochroloma (Coleoptera: Chrysomelidae), in organic crucifer production

BACKGROUND: Yellowmargined leaf beetle, Microtheca ochroloma, is the most damaging pest of organic crucifer crops in the southern United States. Experiments were conducted over four growing seasons (2007–2010) in Alabama to evaluate some botanical and microbial insecticides approved by the Organic Materials Review Institute (OMRI) against M. ochroloma in organically grown crucifer crops. Insecticides evaluated included PyGanic^® (pyrethrum), Aza‐Direct^® (azadiractin), Entrust^® (spinosad), Mycotrol O^® (Beauveria bassiana strain GHA) and NOFLY^® [Isaria ( = Paecilomyces) fumosoroseus strain FE 9901]. Two experimental organic formulations, Tick‐Ex (Metarhizium anisopliae strain F52) and MBI‐203 (Chromobacterium subtsugae), and one non‐OMRI‐listed formulation, Novodor^® (Bacillus thuringiensis subspecies tenebrionis), were also evaluated. The insecticides were applied as stand‐alone treatments at recommended field rates on a weekly schedule. In 2010, some of the treatments were also evaluated in rotation/alternation with Entrust^®. Insecticide efficacy was determined by comparing densities of M. ochroloma larvae and adults and crop damage ratings in treated versus untreated turnip plots. RESULTS: Entrust^® consistently performed well in suppressing M. ochroloma adults, larvae and crop damage. PyGanic^® was the second best treatment. PyGanic^® or NOFLY^? can be applied in rotation with Entrust^® for effective management of M. ochroloma. CONCLUSION: Entrust^® applied weekly or in alternation with PyGanic^® or NOFLY^? provided acceptable control of M. ochroloma in organic crucifer production. Copyright © 2012 Society of Chemical Industry     

Selectivity of diacylhydrazine insecticides to the predatory bug Orius laevigatus: in vivo and modelling/docking experiments

BACKGROUND: Knowledge of pesticide selectivity to natural enemies is necessary for a successful implementation of biological and chemical control methods in integrated pest management (IPM) programmes. Diacylhydrazine (DAH)‐based ecdysone agonists, also known as moulting‐accelerating compounds (MACs), are considered to be a selective group of insecticides, and their compatibility with predatory Heteroptera, which are used as biological control agents, is known. However, their molecular mode of action has not been explored in beneficial insects such as Orius laevigatus (Fieber) (Hemiptera: Anthocoridae). RESULTS: In this project, in vivo toxicity assays demonstrated that the DAH‐based RH‐5849, tebufenozide and methoxyfenozide have no toxic effect against O. laevigatus. The ligand‐binding domain (LBD) of the ecdysone receptor (EcR) of O. laevigatus was sequenced, and a homology protein model was constructed that confirmed a cavity structure with 12 α‐helices, harbouring the natural insect moulting hormone 20‐hydroxyecdysone. However, docking studies showed that a steric clash occurred for the DAH‐based insecticides owing to a restricted extent of the ligand‐binding cavity of the EcR of O. laevigatus. CONCLUSIONS: The insect toxicity assays demonstrated that MACs are selective for O. laevigatus. The modelling/docking experiments are indications that these pesticides do not bind with the LBD‐EcR of O. laevigatus and support the supposition that they show no biological effects in the predatory bug. These data help in explaining the compatible use of MACs together with predatory bugs in IPM programmes. Copyright © 2012 Society of Chemical Industry     

Aerial electrostatic‐charged sprays for deposition and efficacy against sweet potato whitefly (Bemisia tabaci) on cotton

Background: The efficacy of aerial electrostatic‐charged sprays was evaluated for spray deposit characteristics and season‐long control of sweet potato whitefly (SWF), Bemisia tabaci Genn. biotype B (aka B. argentifolii Bellows & Perring), in an irrigated 24 ha cotton field. Treatments included electrostatic‐charged sprays at full and half active ingredient (AI) label rate, uncharged sprays and conventional sprays applied with CP nozzles at full label rate with several different insecticides. Results: Spray droplet size was significantly smaller for electrostatic‐charged sprays than for conventional sprays in top‐ and mid‐canopy locations. The seasonal mean numbers of viable eggs and live large nymphs on cotton treated with electrostatic‐charged sprays were comparable with those on cotton treated with conventional applications. Lethal concentration (LC₅₀) for adults for electrostatic‐charged sprays was comparable with that for conventional sprays. Conclusion: The amenability of electrostatic‐charged sprays to a wide array of pesticides with different chemistries should be a useful tool in combating insect resistance. Results reported here suggest that the potential exists for obtaining increased efficacy against whiteflies using an electrostatic spray charging system, and that additional research will be required to improve charge‐to‐mass (Q/M) ratio in order to increase deposition of pest control materials to the lower surfaces of cotton leaves where the whiteflies reside. Copyright © 2009 Society of Chemical Industry     

Sublethal effect of Beauveria bassiana on feeding and fecundity of the sunn pest,Eurygaster integriceps Puton (Hemiptera: Scutelleridae)

The sunn pest, Eurygaster integriceps Puton, is a major pest of wheat in West and Central Asia. Studies were conducted to investigate the effect of Beauveria bassiana (teleomorph; Cordyceps bassiana) isolates on the sunn pest. Bioassays were done with adult insects collected from overwintering sites at three different times. The effect of sublethal doses of fungi on the insects’ feeding and fecundity was determined. When the sunn pest adults were treated with 2 × 10⁷ conidia mL^?1, all isolates caused significant sunn pest mortality varying between 24 and 100% 12 days after inoculation. There were significant differences between mortality, depending on the date of fungal application. Adult sunn pests treated with B. bassiana at sublethal concentrations caused significantly less damage to wheat leaves than sunn pests in the control. The number of eggs laid by the sunn pest was significantly fewer when wheat plots in plastic greenhouse and field cages were infested with adult sunn pests treated at sublethal concentrations, compared with sunn pests in control plots. Results show that sublethal dosages of B. bassiana reduced sunn pest feeding and fecundity. Applying B. bassiana in sunn pest overwintering sites minimizes the pest populations, which would move to wheat fields in spring.     

Mode of action of methoprene in affecting female reproduction in the African malaria mosquito,Anopheles gambiae

BACKGROUND: One of the most studied actions of juvenile hormone (JH) is its ability to modulate ecdysteroid signaling during insect development and metamorphosis. Previous studies in mosquitoes showed that 20‐hydroxyecdysone (20E) regulates vitellogenin synthesis. However, the action of JH and its mimics, e.g. methoprene, on female reproduction of mosquitoes remains unknown. RESULTS: Here, a major malaria vector, Anopheles gambiae Giles, was used as a model insect to study the action of methoprene on female reproduction. Ecdysteroid titers and expression profiles of ecdysone‐regulated genes were determined before and after a blood meal. An ecdysteroid peak was detected at 12 h post blood meal (PBM). The maximum expression of ecdysone‐regulated genes, such as ecdysone receptor (EcR), hormone receptor 3 (HR3) and vitellogenin (Vg) gene, coincided with the ecdysteroid peak. Interestingly, topical application of methoprene at 6 h PBM delayed ovarian development and egg maturation by suppressing the expression of ecdysone‐regulated genes in female mosquitoes. CONCLUSION: The data suggest that ecdysteroid titers are correlated with Vg synthesis, and methoprene affects vitellogenesis by modulating ecdysteroid action in A. gambiae. Copyright © 2010 Society of Chemical Industry     

不同寄主植物对苜蓿盲蝽种群增长的影响

在自然变温条件下研究了4种寄主植物对苜蓿盲蝽生长、发育和繁殖的影响。结果表明:取食不同寄主植物的苜蓿盲蝽,其发育历期、存活率、若虫平均体重、成虫的繁殖力、寿命及各生命参数均有明显差异。供试植物中,苜蓿为嗜食寄主,棉花次之,莱豆和芝麻为非嗜食寄主。此研究为棉田合理的间套方式提供了依据。