Compatibility of Microplitis manilae with reduced concentration microbial biopesticides under pre- and post-parasitization laboratory conditions

NURSYIFA NADA HARIYADI (Graduate Program of Integrated Pest Management, Institut Pertanian Bogor. Jl. Kamper, IPB Dramaga Campus, Bogor 16680, West Java, Indonesia)
RULY ANWAR (Department of Plant Protection, Faculty of Agriculture, Institut Pertanian Bogor. Jl. Kamper, IPB Dramaga Campus, Bogor 16680, West Java, Indonesia)
NINA MARYANA (Department of Plant Protection, Faculty of Agriculture, Institut Pertanian Bogor. Jl. Kamper, IPB Dramaga Campus, Bogor 16680, West Java, Indonesia)

Biodiversitas Journal of Biological Diversity
Vol. 27 No. 9 (2026)

Abstract. Hariyadi NN, Anwar R, Maryana N. 2026. Compatibility of Microplitis manilae with reduced concentration microbial biopesticides under pre- and post-parasitization laboratory conditions. Biodiversitas 27 (9): d270913. https://doi.org/10.13057/biodiv/d270913. Heavy reliance on synthetic insecticides for managing the invasive pest Spodoptera frugiperda underscores the urgency of integrating biological control agents, particularly the indigenous endoparasitoid Microplitis manilae, with microbial entomopathogens. This study evaluated the compatibility of commercial formulations of Bacillus thuringiensis and Metarhizium anisopliae, applied at half the recommended field concentrations, based on the biocontrol efficacy and pre-adult parameters of M. manilae. The experiment was conducted using a Randomized Block Design (RBD), analyzed via Linear Mixed-effects Models (LMM), in which the time cohort defined as a random effect. Based on the parasitization-rate reduction criteria set by the International Organization for Biological Control (IOBC), both biopesticides were classified as Class 1 (Harmless). However, significant sublethal effects were observed. Pre-parasitization exposure to M. anisopliae significantly prolonged the egg-larval and pupal development stages compared to the control, it also induced a strong male-biased sex ratio, reducing the female proportion to 28.60%. Conversely, a significant reduction in adult female longevity was observed following post-parasitization exposure to B. thuringiensis, with a mean longevity of 21.46 days compared to 26.84 days in the control group. Preliminary qualitative observations revealed rare physical malformations affecting the distal antennal segments of two eclosed female adults in the post-parasitization treatment. These laboratory findings provide an initial indication that post-parasitization application may be less disruptive at reduced concentrations, thereby offering a safer integration strategy in sustainable pest management programs for S. frugiperda.