The Nonlinear Library EA - Research summary: farmed yellow mealworm welfare by abrahamrowe
Jan 3, 2024
13:33
Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Research summary: farmed yellow mealworm welfare, published by abrahamrowe on January 3, 2024 on The Effective Altruism Forum.
This post is a short summary of a peer-reviewed, open access publication on yellow mealworm welfare in the Journal of Insects as Food and Feed. The paper and supplemental information can be accessed
here. The original paper was written by Meghan Barrett, Rebekah Keating Godfrey, Alexandra Schnell, and Bob Fischer; the research conducted in the paper was funded by Rethink Priorities.
This post was written by Abraham Rowe and reviewed by Meghan Barrett. Unless cited otherwise, all information is derived from the Barrett et al. 2023 publication.
Summary
As of 2020, around 300 billion yellow mealworms (Tenebrio molitor) are farmed annually (though recent estimates now put this figure at over 3 trillion individuals (
Pells, 2023
)).
Barrett et al. 2023 is the first publication to consider species-specific welfare concerns for farmed mealworms.
The authors identify 15 current and future welfare concerns, including more pressing current concerns such as:
Disease - Bacterial, fungal, protist, and viral pathogens can cause sluggishness, tissue damage, slowed growth, increased susceptibility to other diseases, and even mass-mortality events.
High larval rearing densities - Density can cause a range of negative effects, including increased cannibalism and disease, higher chances of heat-related death, competition over food leading to malnutrition, and behavioral restriction near pupation.
Inadequate larval nutrition - This may result from not providing enough protein in the animals' largely grains-based diet.
Light use during handling - Photophobic adults and larvae may experience significant stress due to light use during handling.
Slaughter methods - While we have high empirical uncertainty about the relative harms of slaughter methods, it is clear that some approaches to slaughter and depopulation on farms are more harmful than others.
Future concerns that haven't yet been realized on farms include:
Novel, potentially toxic, or inadequate feed substrates - Polymers (like plastics) and mycotoxin-contaminated grains may be more likely to be used in the future.
Selective breeding and genetic modification - In vertebrate animals, selective breeding has caused a large number of welfare issues. The same might be expected to become true for mealworms.
Current rearing and slaughter practices
Yellow mealworms are the larval instars of a species of darkling beetle, Tenebrio molitor. Larvae go through a number of molts prior to pupation, which can take between a few months to two years depending on nutrition and abiotic conditions. Mealworms take up to 20 days to pupate. After pupating, the emerged adult beetles will mate within 3-5 days. Mealworms are a popular insect to farm for food due to their rapid growth, high nutrient content, and ease of handling. Adults are typically only used for breeding, while large larvae are sold as food and feed.
Mealworms typically consume decaying grains, but have been reported to eat a wide variety of other foods in certain circumstances (including dead insects, other mealworms, and decaying wood). In farmed conditions, larval mealworms are fed a diet of 70%-85% cereals and other carbohydrates, and may be provided with supplementary protein, fruit, or vegetables.
Mealworms are reared in stackable crates, usually with screened bottoms to allow frass (insect excrement) to fall through and not accumulate. Mealworms may be reared in up to 24-hour darkness, as they are photophobic.
Insects bound for slaughter are collected at around 100 mg. Prior to slaughter, insects are sieved out of the substrate, washed (to remove frass and other waste from the exterior surface of their bodies), and prevented from eating for up to two days (ca...
This post is a short summary of a peer-reviewed, open access publication on yellow mealworm welfare in the Journal of Insects as Food and Feed. The paper and supplemental information can be accessed
here. The original paper was written by Meghan Barrett, Rebekah Keating Godfrey, Alexandra Schnell, and Bob Fischer; the research conducted in the paper was funded by Rethink Priorities.
This post was written by Abraham Rowe and reviewed by Meghan Barrett. Unless cited otherwise, all information is derived from the Barrett et al. 2023 publication.
Summary
As of 2020, around 300 billion yellow mealworms (Tenebrio molitor) are farmed annually (though recent estimates now put this figure at over 3 trillion individuals (
Pells, 2023
)).
Barrett et al. 2023 is the first publication to consider species-specific welfare concerns for farmed mealworms.
The authors identify 15 current and future welfare concerns, including more pressing current concerns such as:
Disease - Bacterial, fungal, protist, and viral pathogens can cause sluggishness, tissue damage, slowed growth, increased susceptibility to other diseases, and even mass-mortality events.
High larval rearing densities - Density can cause a range of negative effects, including increased cannibalism and disease, higher chances of heat-related death, competition over food leading to malnutrition, and behavioral restriction near pupation.
Inadequate larval nutrition - This may result from not providing enough protein in the animals' largely grains-based diet.
Light use during handling - Photophobic adults and larvae may experience significant stress due to light use during handling.
Slaughter methods - While we have high empirical uncertainty about the relative harms of slaughter methods, it is clear that some approaches to slaughter and depopulation on farms are more harmful than others.
Future concerns that haven't yet been realized on farms include:
Novel, potentially toxic, or inadequate feed substrates - Polymers (like plastics) and mycotoxin-contaminated grains may be more likely to be used in the future.
Selective breeding and genetic modification - In vertebrate animals, selective breeding has caused a large number of welfare issues. The same might be expected to become true for mealworms.
Current rearing and slaughter practices
Yellow mealworms are the larval instars of a species of darkling beetle, Tenebrio molitor. Larvae go through a number of molts prior to pupation, which can take between a few months to two years depending on nutrition and abiotic conditions. Mealworms take up to 20 days to pupate. After pupating, the emerged adult beetles will mate within 3-5 days. Mealworms are a popular insect to farm for food due to their rapid growth, high nutrient content, and ease of handling. Adults are typically only used for breeding, while large larvae are sold as food and feed.
Mealworms typically consume decaying grains, but have been reported to eat a wide variety of other foods in certain circumstances (including dead insects, other mealworms, and decaying wood). In farmed conditions, larval mealworms are fed a diet of 70%-85% cereals and other carbohydrates, and may be provided with supplementary protein, fruit, or vegetables.
Mealworms are reared in stackable crates, usually with screened bottoms to allow frass (insect excrement) to fall through and not accumulate. Mealworms may be reared in up to 24-hour darkness, as they are photophobic.
Insects bound for slaughter are collected at around 100 mg. Prior to slaughter, insects are sieved out of the substrate, washed (to remove frass and other waste from the exterior surface of their bodies), and prevented from eating for up to two days (ca...