Metarhizium: papers, findings & open questions
Read the original fungal-biological-control research, with the insect species, study setting, and limits kept visible.
Metarhizium research offers important leads for coconut rhinoceros beetle management. This collection links papers and public research records for community review. Laboratory mortality, field suppression, colony elimination, product efficacy, and permission to use a product are separate questions.
CRB in Sri Lanka: laboratory and field results differ
Fernando, Kanagaratnam and Narangoda’s paper appeared in COCOS in 1995; its online publication record is dated 2010. It studied three fungal isolates then identified as Metarhizium anisopliae. The laboratory experiments reported 100% fungus-attributed mortality, with nonfungal deaths excluded from that calculation.
The field experiment used 24 boxes, split between treated and untreated groups. The fungus also reached controls, and the authors reported lower field pathogenicity. The laboratory percentage must not be presented as 100% field control. Read the original paper using the first reference below.
Read the source: Fernando, Kanagaratnam & Narangoda (1995)
CRB in Indonesia: the isolate matters
Prastowo and colleagues (2022) compared 13 isolates using third-instar CRB larvae under laboratory conditions. The Metarhizium majus isolate MaWa reached 100% mortality by day 13; another M. majus isolate, MaMa, had the shortest estimated time to 50% mortality.
These are results for identified isolates and experimental conditions. They do not establish the same performance for every fungus or commercial formulation called Metarhizium, and they are not a Hawaiʻi field trial.
Read the source: Prastowo et al. (2022)
Pacific research: a promising field result with important limits
Villamizar and colleagues (2024) screened Pacific isolates and tested M. majus AgR-F717 against CRB. That isolate produced 100% mortality in laboratory trials. Field work in the Solomon Islands recorded infection, persistence for at least four months, and spread up to 100 meters.
Treated field bins had fewer larvae at month four, but the difference was not statistically significant at months two or six. Spread into untreated bins complicates the comparison. This supports further field evaluation; it does not establish island-wide eradication, lasting palm protection, or a verified Hawaiʻi product claim.
Read the source: Villamizar et al. (2024) · Villamizar et al. (2024)
Little fire ant: keep the species and evidence separate
The little-fire-ant literature cited here uses the name Wasmannia auropunctata. Results for coconut rhinoceros beetle, red imported fire ant (Solenopsis invicta), or another ant cannot be treated as results for this species.
A library catalog records a 1991 paper by Castiñeiras, Neyra, Fernandez-Larrea and Ponce evaluating fungal and bacterial strains against W. auropunctata. We have verified the bibliographic record, but have not reviewed the paper’s methods or results. The catalog link is a route to finding the paper, not evidence of successful colony control.
HISC’s approved FY26 projects include $100,000 for organic little-fire-ant management research. A funded project establishes a research commitment, not a completed efficacy result. The sources reviewed here do not establish one inexpensive organic treatment that reliably controls both CRB and established little-fire-ant colonies in Hawaiʻi.
Read the source: Castiñeiras et al. (1991) · State HISC
From a research isolate to an available product
A species name alone does not identify the strain, viable dose, formulation, or quality of a product. A product-specific claim needs evidence connecting that product to the reported results. Likewise, the registration of one strain does not establish authorization for other strains or formulations.
EPA’s record identifies Metarhizium brunneum strain F52, formerly called M. anisopliae strain F52, as first registered in 2003. That is a specific regulatory record. State HISC also discusses Metarhizium as a CRB biological-control candidate and reports availability and registration limitations in Hawaiʻi. Check current agency records for the exact proposed product and use.
These research links are not application instructions, product recommendations, or evidence that modern fungal biocontrol is an ancestral Hawaiian practice. Place-specific Hawaiian knowledge should be attributed to its knowledge holders and shared with their permission.
Read the source: EPA · State HISC · University of Hawaiʻi (2024)
Read and evaluate the papers
The references below link to publisher pages, article records, and public agency records. We have not copied or republished the papers. Access to the full text may depend on the publisher; the 1991 ant paper is currently a bibliographic lead only.
- Match the insect species and life stage to the problem being addressed.
- Record the fungal species and isolate, setting, comparison, sample size, and follow-up.
- Separate mortality from lower population density, reduced plant damage, and elimination of an ant colony.
- Look for adverse effects, unsuccessful observations, commercial interests, and labor and cost data.
- For Hawaiʻi use, evaluate local field performance, non-target effects, and the exact product’s current authorization.
Sources & further reading
References support the topics discussed above. A link does not imply partnership or endorsement. Some external sources also discuss treatments outside this site’s nonchemical scope.
- Fernando, Kanagaratnam & Narangoda (1995) — Metarhizium and CRB in Sri Lanka
COCOS 10:46–52; online record dated 2010. Primary paper reviewed in full. Laboratory and field experiments; fungal spread into controls limits the field comparison.
- Prastowo et al. (2022) — Virulence of Metarhizium isolates from East Java
Primary paper reviewed in full. Laboratory comparison of 13 isolates against CRB larvae; performance is isolate-specific.
- Villamizar et al. (2024) — New Metarhizium isolates for CRB in the Pacific
Primary paper reviewed in full. Laboratory screening and Solomon Islands field experiments. Field results vary by observation time; this is not Hawaiʻi field validation.
- Villamizar et al. (2024) — PubMed abstract and article record
An additional public route to the abstract, author list, publication details, and publisher link.
- Castiñeiras et al. (1991) — Historical Wasmannia auropunctata paper: catalog record
Bibliographic lead only. Revista de Protección Vegetal 6(1):21–26. The title concerns evaluation of Beauveria, Metarhizium and Bacillus strains against W. auropunctata; methods, results and field relevance have not been reviewed.
- State HISC — Approved FY26 funded projects
Public funding record includes $100,000 for organic little-fire-ant management research. Funding is not an efficacy finding.
- EPA — Metarhizium brunneum strain F52 chemical record
Specific strain record, formerly named M. anisopliae strain F52; first registration listed as 2003. It does not establish approval or performance of another strain or formulation.
- State HISC — Biological and chemical options for CRB control
Institutional discussion acknowledging Metarhizium and describing Hawaiʻi availability and registration limitations. External page also discusses methods outside this site’s scope.
- University of Hawaiʻi (2024) — Testimony on biological control research
Testimony on mycopesticide strain specificity, research feasibility, and potential risks to native species; not a completed efficacy trial.