House Crickets Now Have a Frailty Index, and Rapamycin Lowers It

House Crickets Now Have a Frailty Index, and Rapamycin Lowers It
On September 17, the geropathology group led by Warren Ladiges at the University of Washington published a composite frailty index for the house cricket Acheta domesticus in the peer-reviewed journal npj Aging. This is the first quantitative measure of functional aging for the species. The index increased with age in young versus old crickets, and in a separate middle-aged cohort it decreased under rapamycin treatment. Acarbose and phenylbutyrate showed no effect under the same conditions.

In humans, frailty is a state distinct from chronological age: a decline in physiological reserves that predicts risk better than years lived. Geriatricians measure it by summing scores across individual markers of aging, and the authors applied the same logic to the cricket. Cheap, fast invertebrate models had no such measure before. The usual endpoint was lifespan alone, which says nothing about what happens to the body on the way to death.

Video tracking recorded ten behavioral parameters: walking and running speed, freezing episodes, and time spent and distance traveled in the center versus the periphery of the arena, separating locomotor speed from exploratory willingness. Each parameter was compared to a reference group, converted to a score from 0 to 4, and summed into an overall frailty index ranging from 0 to 1, where higher values indicate greater decline.

In cohorts of young (4 to 6 weeks) and old (10 to 12 weeks) crickets, the index rose by nearly the same amount in both sexes, and the magnitude was large: from 0.38 to 0.65 in females, from 0.38 to 0.67 in males.

The index was then tested against drugs. Middle-aged crickets (8 weeks) were fed rapamycin, acarbose, or phenylbutyrate for two weeks at doses drawn from the Interventions Testing Program (ITP) of the U.S. National Institute on Aging, the standard mouse-based geroprotector screening program. The reasoning was straightforward: if the cricket index reproduces an effect already established in mice, that confirms the instrument is measuring aging. By week 10, the frailty index in the rapamycin group had dropped to roughly half the control value in both sexes. Acarbose and phenylbutyrate produced no significant effect.

The authors are cautious about ruling these two compounds out:

This should not be taken as evidence that acarbose or phenylbutyrate cannot reduce frailty in crickets. Rather, no measurable improvement was detected under the present experimental conditions.

There is a more concerning signal for acarbose: in an earlier experiment by the same group using intermittent dosing, it significantly reduced survival in female crickets, while rapamycin, conversely, extended it.

This paper is the fifth step in the Ladiges laboratory's program. Since 2024, the group first proposed the cricket as a model organism, then confirmed its age-related changes, and in 2025 showed that memory and behavioral decline begins at 8 to 10 weeks. The current trial was timed to that window, capturing the drug effect before the species reaches its natural lifespan limit.

The tool is intended as a fast, inexpensive first filter for geroprotector candidates (metformin, SGLT2 inhibitors, GLP-1 agonists, all originally developed for diabetes) before committing $100,000 to $300,000 and three to four years to mouse trials, as an analysis of ITP data has shown. The paper did not test whether the index translates to mammals or to humans.