Black soldier fly (Diptera: Stratiomyidae) larvae reduce cyathostomin (Nematoda: Strongylidae) eggs but develop poorly on horse manure.

The researchers explored the potential of black soldier fly larvae to reduce the number of cyathostomin eggs in horse manure, finding that although the larvae develop poorly on this substrate, they reduce egg densities significantly, which could be an important tool in controlling these parasites.

Study Overview and Objective

• The main objective of this study was to evaluate the effect of black soldier fly larvae (BSFL) on the density of cyathostomin eggs in horse manure. Cyathostomins are common digestive tract parasites found in grazing horses and they can easily spread their eggs via horse feces.
• The researchers used feeding bioassays to compare the larvae’s development on horse manure, which is nutrient-poor, to its development on standard grain-based diets. The larval development was tracked and the reduction in cyathostomin egg density was measured.

Key Findings

• BSFL consumed less substrate, took longer to reach the prepupal stage, and yielded less biomass when reared on horse manure in comparison to grain-based diets, which suggests the manure is not ideal for their growth.
• Despite this, BSFL dramatically reduced average cyathostomin egg densities in horse manure by over three times.

Implications of the Research

• This research revealed that BSFL effectively reduces the cyathostomin egg loads in infected horse manure, despite poor growth conditions in the manure, although the exact mechanism remains unknown.
• The results also hint at the potential underappreciated effects of BSFL on larger, parasitic organisms within animal manures, beyond transforming microbial communities in a diversity of rearing substrates.
• This suggests that using BSFL to promote decomposition of infected horse manure may be a promising approach to managing parasite populations among grazing horses, although more research needs to be conducted to understand exactly how this reduction occurs.