Effects of egg-mass-dissolving substances on the post-embryonic development of Chrysomya megacephala (Fabricius, 1794) and Chrysomya putoria (Wiedemann, 1830) (Diptera: Calliphoridae): Implications for maggot therapy

Maggot therapy uses necrophagous dipteran larvae to remove necrotic tissue, requiring strict aseptic protocols. The disruption of egg masses is a crucial step to ensure uniform disinfection; however, chemical agents can cause sublethal effects. This study investigated the impact of three disrupting compounds on the post-embryonic development of Chrysomya megacephala and Chrysomya putoria. Egg masses were subjected for 10 minutes to the following treatments: papain (0.5%), sodium hydroxide (NaOH 1%), potassium hydroxide (KOH 2%), and a control (distilled water). After hatching, 40 larvae per replicate (n = 640 per species) were monitored for viability, stage duration, feeding cessation rate, larval weight (L3), sex ratio, and morphological normality. Data normality was assessed using the Shapiro-Wilk test; comparisons between treatments were performed using nonparametric Kruskal-Wallis tests followed by Dunn's post hoc tests, while categorical variables were analyzed using chi-square tests and Fisher's exact test, with a significance level of p < 0.05. The results revealed species-specific responses. In Chrysomya megacephala, there was no significant reduction in viability (57% to 70%) or changes in the pupation rate among the groups. However, NaOH significantly reduced larval weight (67.5 mg) compared to the control (69.9 mg), while papain did not differ significantly from the control (68.5 mg). Chrysomya putoria, on the other hand, showed greater sensitivity to alkaline compounds; treatments with NaOH and KOH reduced total viability to 68% (compared to 88-91% in the control and papain groups) and delayed the feeding cessation rate. In both species, papain preserved larval weight gain and maintained developmental stability. The total duration of the life cycle (10-11 days) and the morphological normality of adults were not significantly affected by the treatments. It is concluded that C. megacephala exhibits greater physiological resilience to chemical stress in early life stages. Among the agents tested, 0.5% papain emerged as the most promising option for maggot therapy protocols, as it combines efficient dissociation with the maintenance of larval biological quality.