The potential of soil amendment with insect exuviae and frass to control the cabbage root fly

Abstract

Reliable options to control the cabbage root fly, Delia radicum L., are lacking in many countries as restrictions on insecticide use have tightened due to environmental concerns. Although microbial control agents are often considered as a sustainable alternative, their application in agriculture is constrained by inconsistent efficacy owing to low field persistence. To stimulate naturally occurring beneficial microbes, soil amendment with the residual streams of insect production has been suggested as an alternative to synthetic fertilization and a new approach to microbial crop protection. In a set of greenhouse experiments, exuviae and frass of black soldier fly larvae, Hermetia illucens L., house crickets, Acheta domesticus L. and exuviae of mealworms, Tenebrio molitor L., were added to soil from an organically managed field. Exuviae and frass treatments were compared to treatments with synthetic fertilizer. Brussels sprouts, Brassica oleracea L., plants were grown in amended soil for 5 weeks before being infested with cabbage root fly larvae. Insect and plant performance were assessed by recording cabbage root fly survival, biomass and eclosion time and seed germination and plant biomass, respectively. Whereas soil amendment with black

Effects of frass from larvae of black soldier fly (Hermetia illucens) and yellow mealworm (Tenebrio molitor) on growth and insect resistance in field mustard (Brassica rapa): differences between insect species and frass treatments

“…To date, there is limited research on the potential of frass to enhance plant development and resistance to insect herbivory. A recent study showed that mealworm exuviae did not affect shoot and root dry biomass of B. oleracea (Wantulla et al., 2022). The study further recorded reduced survival of D. radicum larvae in BSFF‐exposed soil, but mealworm exuviae did not affect larval survival and biomass compared to a synthetic fertilizer.…”

“…However, Wantulla et al. (2022) did not investigate the effects of MWF, which is the most abundant byproduct of mealworm cultivation. They focused on a root‐feeding pest, D. radicum , and did not include shoot‐feeding insect pests.…”

“…Intriguingly, whether insect frass can replace traditional organic and mineral fertilizers and chemical insecticides in agricultural systems still requires further research. There is currently no single paper that addressed this question, and several studies on soil fertility have mainly focused on frass application to improve soil health and promote plant growth, with limited attention to its potential effect on insect herbivore performance (Poveda, 2021; Wantulla et al., 2022). Exploring the effects of insect frass on plant resistance to herbivores may provide insights into its use as a pest management strategy and reduce the need for chemical pesticides.…”

“…The study further recorded reduced survival of D. radicum larvae in BSFF-exposed soil, but mealworm exuviae did not affect larval survival and biomass compared to a synthetic fertilizer. However, Wantulla et al (2022) did not investigate the effects of MWF, which is the most abundant byproduct of mealworm cultivation. They focused on a root-feeding pest, D. radicum, and did not include shoot-feeding insect pests.…”

“…They focused on a root-feeding pest, D. radicum, and did not include shoot-feeding insect pests. Additionally, Wantulla et al (2022) did not investigate the effects of preprocessing insect residual streams. Furthermore, evaluations of plant growth in frass-amended soil and herbivore performance on such plants have been limited to a few plant species and insect herbivores under soil treatment with frass, thus limiting the generalization of the results.…”