A research update on the food value of Prionoplus reticularis (Huhu grub), an indigenous edible insect of New Zealand

Figures & data

Figure 1. Huhu grub in a decaying pine wood cavity.

Figure 2. Representative developmental stages of Prionoplus reticularis (egg, small-, medium-, and large- larva, pupa, and adult beetle) derived from Kavle (2023).

Table 1. Anthropometric parameters of Huhu grub larvae and pupae; The data were derived from Kavle et al. (2022a).

Parameters	Small larvae	Medium larvae	Large larvae	Pupae
*Weight (g)	1.9 ± 0.4	3.5 ± 0.1	4.3 ± 0.1	3.6 ± 0.2
*Length (cm)	1.3 ± 0.1	2.3 ± 0.1	3.6 ± 0.1	2.4 ± 0.3

*Measurement was performed as reported in Kavle et al. (2022a); Results are presented as means ± standard deviation (SD).

Table 2. Table of previous studies on huhu grubs reported in the literature.

No.	Title	Year	Scope of study	References
1	Host range in Prionoplus reticularis White	1959	First report of huhu grubs presence in exotic conifer forests	Edwards (1959)
2	Observations on the biology of the immature stages of Prionoplus reticularis White (Col. Ceramb.).	1961	Laboratory and field observations study Huhu had a ∼ 23-day egg incubation period and an average larval stage lasting 2–3 years in the wild.	Edwards (1961a)
3	Observations on the ecology and behaviour of the huhu beetle, Prionoplus reticularis White. (Col.: Ceramb.)	1961	Phenology and flight activity patterns of adult insects studied Combat, copulation, and oviposition behaviours documented.	Edwards (1961b)
4	Fatty acid composition of huhu larvae (Prionoplus reticularis) in relation to their food source.	1973	Fatty acid content of huhu grubs, their food supply, and frass analysed Differences in lipid content of larvae, food supply, and frass. Resin acids in pine wood absent in huhu lipids.	Hutchins and Christmas (1973)
5	Mortality of huhu (Prionoplus reticularis) subjected to heat and controlled atmosphere treatments	1999	Survival of huhu grub eggs and larvae at high temperatures under varying controlled atmosphere conditions during wood disinfection for export purposes.	Dentener et al. (1999)
6	Rearing huhu beetle larvae, Prionoplus reticularis (Coleoptera: Cerambycidae) on artificial diet.	2002	Lab grown Huhu grubs reared on a pine sawdust artificial diet exhibited a reduced larval period of 250 days, compared to at least two years in the wild. Artificial diet proved beneficial for raising wild-caught larvae to produce adult beetles for taxonomic research.	Rogers et al. (2002)
7	Biodiversity of active and inactive bacteria in the gut flora of wood ̶ feeding huhu beetle larvae (Prionoplus reticularis).	2011	Pyrosequencing to evaluate the diversity of metabolically active and inactive bacteria in the Huhu grub larval gut Insights into role of gut bacteria in digesting the nutritionally poor wood diet consumed by Huhu larvae.	Reid et al. (2011)
8	The microflora of the huhu grub	2011	Microbial communities in wild huhu grubs and Huhu grubs fed different laboratory formulated diets were examined. Candida shehatae was the dominant microbe when Huhu grubs were fed only cellulose, indicating potential for lignocellulose biodegradation.	Williams (2011)
9	Investigating the lignocellulolytic gut microbiome of huhu grubs	2016	Huhu grubs reared on either pine blocks (lignocellulose) or cotton (cellulose) Gut microbiome analysed to identify novel lignocellulolytic microbes.	Viswam et al. (2019)
10	Huhu grubs, bull semen shots and koki: Visceral geographies of regional food festivals in Aotearoa.	2017	Wild food festivals in New Zealand, featuring huhu grub consumption are highlighted in this study to offer insights into regional and cultural diversity in tourism geographies.	Modlik and Johnston (2017)
11	Macronutrients and mineral composition of wild harvested Prionoplus reticularis edible insects at various development stages: nutritional and mineral safety implications	2022	Huhu grubs at various developmental stages reported to be rich in major nutrients and minerals, Safely and nutrition of Huhu grubs asserted.	Kavle et al. (2022a)
12	Proximate composition and lipid nutritional indices of larvae and pupae of the edible huhu beetle (Prionoplus reticularis) endemic to New Zealand	2022	Variations in lipid content and fatty acid profiles among different developmental stages of huhu grubs were observed, emphasising differences in their nutritional characteristics.	Kavle et al. (2022b)
13	Physicochemical characteristics, techno-functionalities, and amino acid profile of Prionoplus reticularis (huhu) larvae and pupae protein extracts	2023	Protein extracts from huhu grub larvae and pupae exhibited substantial essential amino acid content, indicating high nutritional quality. Huhu grubs protein extracts displayed favourable techno-functional properties such as foaming and emulsifying capacities, suggesting potential for application in food technology.	Kavle et al. (2023)

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Hutchins R, Christmas P. 1973. Fatty acid composition of huhu larvae (Prionoplus reticularis) in relation to their food source. New Zealand Journal of Science. 16(1):155–159.

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Dentener PR, Lewthwaite SE, Rogers DJ, Miller M, Connolly PG. 1999. Mortality of huhu (Prionoplus reticularis) subjected to heat and controlled atmosphere treatments. New Zealand Journal of Forestry Science. 29(3):473–483.

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Reid NM, Addison SL, Macdonald LJ, Lloyd-Jones G. 2011. Biodiversity of active and inactive bacteria in the gut flora of wood-feeding huhu beetle larvae (Prionoplus reticularis). Applied and Environmental Microbiology. 77(19):7000–7006. doi:10.1128/AEM.05609-11.

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Williams TC. 2011. The microflora of the Huhu grub. Hamilton, New Zealand: University of Waikato.

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Viswam JP, Lee CK, Morgan HW, McDonald IR. 2019. Laboratory rearing of huhu, Prionoplus reticularis (Cerambycidae): insights into the gut microbiome. New Zealand Journal of Zoology. 46(1):1–12. doi:10.1080/03014223.2018.1461117.

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Modlik M, Johnston L. 2017. Huhu grubs, bull semen shots and koki: visceral geographies of regional food festivals in Aotearoa. New Zealand Geographer. 73(1):25–34. doi:10.1111/nzg.12148.

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Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.