Laboratory screening of entomopathogenic fungi and nematodes for pathogenicity against the obscure mealybug, <i>Pseudococcus viburni</i> (Hemiptera: Pseudococcidae)

Mathulwe, Letodi Luki; Malan, Antoinette P.; Stokwe, Nomakholwa Faith

doi:10.1080/09583157.2021.2010653

Cited by 5 publications

(6 citation statements)

References 34 publications

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“…Indeed, the MHK isolate was as efficient in reducing larval survival and impacting mosquito development as the GHA isolate. Similar results have been reported in studies assessing the entomopathogenic activity of local B. bassiana isolates towards several insects, including mealybug adults and red palm weevils, as compared to commercially available isolates (Sutanto et al 2021, Mathulwe et al 2022). While we acknowledge that statistical evaluation of efficacy between the two fungal isolates is not possible in our study, as larval exposures were conducted using different mosquito generations, our study confirms that the entomopathogenicity of B. bassiana on mosquito larvae is maintained in the MHK isolate.…”

Section: Discussionsupporting

confidence: 86%

The potential of the Beauveria bassiana MHK isolate for mosquito larval control

Tawidian

Kang

Michel

2022

Preprint

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The African malaria mosquito, Anopheles gambiae Giles (Diptera: Culicidae), and the Asian tiger mosquito, Aedes albopictus Skuse (Diptera: Culicidae) are of public health concern due to their ability to transmit disease-causing parasites and pathogens. Current mosquito control strategies to prevent vector-borne diseases rely mainly on the use of chemicals. However, insecticide resistance in mosquito populations necessitates alternative control measures, including biologicals such as entomopathogenic fungi. Here we report the impact of a Beauveria bassiana (Balsamo) Vuillemin (Hyprocreales: Cordycipitaeceae) isolate, MHK, isolated from field-collected Ae. albopictus larvae on mosquito survival and development. Larval infection bioassays using three B. bassiana conidial doses were performed on the second and third larval instars of An. gambiae and Ae. albopictus mosquitoes. Larvae were monitored daily for survival and development to pupae and adults. Our results show that B. bassiana MHK was more effective in killing An. gambiae than Ae. albopictus larvae. We further observed delays in development to pupae and adults in both mosquito species exposed the varying doses of B. bassiana as compared to the water control. In addition, larval exposure to B. bassiana reduced adult male and female survival in both mosquito species, further contributing to mosquito population control. Thus, this study identifies the locally isolated fungus, B. bassiana MHK, as a possible biological control agent of two mosquito species of public health concern, increasing the arsenal for integrated mosquito control.

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Section: Discussionsupporting

confidence: 86%

The potential of the Beauveria bassiana MHK isolate for mosquito larval control

Tawidian

Kang

Michel

2022

Preprint

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“…Following the above-mentioned procedure, the fungal concentrate in the beaker was poured back into the 28-ml McCartney bottles and vortex-mixed for 2 min. The concentrate was then used as the conidial stock for the serial dilutions (Mathulwe et al 2021). The methods employed by Inglis et al (2012) were followed to quantify the conidial concentration per unit volume.…”

Section: Preparation Of Conidial Suspensionsmentioning

confidence: 99%

Infection of insects and persistence of Metarhizium (Hypocreales: Clavicipitaceae) species on apple bark

2023

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Entomopathogenic fungi (EPF) are cosmopolitan soil borne pathogens that cause epizootics in various insect orders. EPF isolates of Metarhizium brunneum and M. pinghaense have shown the potential for use as biological agents of important agricultural insect pests. The aim of the current study was to test for the persistence of M. brunneum and M. pinghaense on apple bark over a period of three weeks, under laboratory conditions. Apple bark was sprayed with conidial suspensions of both fungi, at a standard infective conidial concentration of 107 conidia/ml. The persistence, or survival, of the conidia on apple bark was measured using codling moth larvae (CM) (Cydia pomonella) and females of woolly apple aphid (WAA) (Eriosoma lanigerum) as indicator species. The results showed that conidia of M. pinghaense can induce mortality of insect pests through contact with an EPF-treated substrate, with mortality of 39% to 82% for WAA over a period of 10 days post application, and with mortality of 3% to 68% for CM over a period of 7 days, after application to apple bark. Further evaluation showed that the conidia of M. pinghaense persisted longer on apple bark, up to 63%, than did M. brunneum, up to 11%, three weeks post application of the conidial suspensions. The study provides insights into the potential persistence of fungal isolates on apple bark over time post application. Further evaluation of the persistence of the isolates on apple bark under both glasshouse and field conditions should be conducted.

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“…The bottles containing conidia were sealed, and vortex-mixed for 2 min to produce a homogenous suspension. The conidial suspension was poured into a sterile 100-ml glass beaker, through an organza fabric, to remove the fungal hyphae and mycelium, before being poured back into the McCartney bottle, vortex-mixed for 2 min, and used as the conidial stock (Mathulwe et al 2022). One ml of the conidial stock was transferred into a McCartney (28 ml) glass bottles containing 9 ml of sterile distilled water, and vortex mixed for 3-4 min to produce a homogenous suspension.…”

Section: Preparation Of Conidial Suspensionsmentioning

confidence: 99%

“…The conidia were counted as viable if they developed a germ tube, and those without a germ tube were counted as non-viable. The average number of viable conidia were calculated from the three plates, and only conidial suspensions with percentage viability of >85% were used in the screening bioassay (Mathulwe et al 2022).…”

Section: Preparation Of Conidial Suspensionsmentioning

confidence: 99%

“…Each insect was placed in an alternate well of a 24-well bioassay plate, which was fitted with a filter disc paper, and inoculated using 50 µl of the produced conidial suspension. To prevent settling of conidia at the bottom of the inoculum, the conidial suspensions were regularly vortex mixed for 20-30 s during the inoculation process (Mathulwe et al 2022). To prevent escape of insects from the wells, each plate was closed with a glass cover.…”

Section: Screening Of Entomopathogenic Fungimentioning

confidence: 99%

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The occurrence of entomopathogenic fungi in apple orchards and their biocontrol potential against Eriosoma lanigerum

Mathulwe¹,

Malan²,

Stokwe

2023

Afr. Entomol.

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Eriosoma lanigerum (Hausmann) (Hemiptera: Aphididae), woolly apple aphid (WAA) is an important pest on apples globally and a key pest of apple production in South Africa. The aphid has developed some level of resistance against several chemical insecticides. Entomopathogenic fungi (EPF) have been identified as promising biological control agents against a wide array of insect pests. The main aim of this study was to conduct a survey in local apple orchards in the Western Cape province for EPF and to use isolates to test the susceptibility of WAA under optimum laboratory conditions. Soil samples were collected from apple orchards and EPF, baited and isolated using larvae of Galleria mellonella and Tenebrio molitor. Six EPF species: Beauveria bassiana, Cordyceps fumosorosea, Metarhizium brunneum, M. pinghaense, M. robertsii and Purpureocillium lilacinum were identified from the soil samples. The results from bioassays showed that Metarhizium robertsii and M. pinghaense isolates were the most effective with an average percentage mortality of > 90%. Metarhizium brunneum also proved to be effective when used against the insect with an average percentage mortality of > 80%, while B. bassiana and C. fumosorosea were the least effective with average percentage mortality of 52% and 48%, respectively. The LT50 and LT90 of M. robertsii (2.12; 4.19) and M. pinghaense (2.05; 4.45) showed to require similar mortality time in days of E. lanigerum. The results obtained in the study have provided an insight into the diversity of EPF species across apple orchards of the Western Cape and shown the efficacy of the Metarhizium isolates as potential biological control agents of the WAA.

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Laboratory screening of entomopathogenic fungi and nematodes for pathogenicity against the obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae)

Cited by 5 publications

References 34 publications

The potential of the Beauveria bassiana MHK isolate for mosquito larval control

The potential of the Beauveria bassiana MHK isolate for mosquito larval control

Infection of insects and persistence of Metarhizium (Hypocreales: Clavicipitaceae) species on apple bark

The occurrence of entomopathogenic fungi in apple orchards and their biocontrol potential against Eriosoma lanigerum

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