Reproduction of Black Soldier Fly (Diptera: Stratiomyidae) under Different Adult Densities and Light Regimes

The
black soldier fly (BSF) Hermetia illucens
L. (Diptera: Stratiomyidae) has been recognized as a promising insect species
for sustainable management of organic waste and by-products. Indoor breeding of
BSF with artificial lighting has been proved successful, but efforts are still
needed to optimize BSF reproductive output. Increasing adult density seems an
option to exploit space, whereas decreasing artificial lighting duration may
reduce unnecessary power consumption. This study aimed at investigating the
effects of adult density (10, 25, and 50 pairs per 30 ×
30 × 30 cm cage; i.e., 370, 926, and 1852 pairs/m3), light
regime (8:16, 12:12, and 16:8 [L:D] h), and their possible interactions, on
some BSF life history traits relevant to reproduction. The results show that
the overall BSF reproductive output increased with increasing adult density but
was not affected by light regimes tested per se. With the highest BSF
adult density tested, an average of more than 20,000 neonate
larvae were produced from a cage within 10 d. At the highest adult density
tested, increasing photoperiod increased neonate production, but also decreased
the number of neonates per watt used for artificial illumination. The temporal
oviposition patterns, mean individual female reproductive output, mating
success, egg hatching rate, and insect survival rate were not affected by adult
density or light regime as simple effects. However, the interaction between
adult density and light regime was significant for the first oviposition peak, mean
individual female reproductive output, and insect survival rate. The possible
mechanisms behind our results are discussed.