PTM rearing innovations

The potato tuber moth (Phthorimaea operculella) is a major pest of solanaceous crops worldwide, including in South Africa. Effective mass-rearing protocols are essential for laboratory research and the implementation of biological control strategies. This study investigated the effects of two ecological regimes on the developmental and reproductive performance of P. operculella under controlled laboratory conditions. The regimes differed in temperature and relative humidity, with the 28 °C regime maintained under continuous darkness and the 21 °C regime under a 12L:12D light cycle. Although light and humidity were not independently controlled, temperature was the primary variable influencing outcomes. Key life stage parameters including fecundity, egg hatch rate, and the duration of egg, larval, and pupal stages were significantly affected by temperature. Females reared at 28 °C laid significantly more eggs (mean ± SD: 2371.46 ± 183.1) than those at 21 °C (1587.30 ± 167.7) (F₁,₉₈ = 181.44, p < 0.001). The egg hatch rate was also higher at 28 °C (83.24%) compared to 21 °C (80.42%) (F₁,₉₈ = 5.99, p = 0.016). Development from egg to adult was markedly faster under the warmer regime, with a total duration of 24.44 days at 28 °C versus 42.60 days at 21 °C (F₁,₉₈ = 368.88, p < 0.001). Individual developmental stages (egg: F₁,₉₈ = 1307.87, larva: F₁,₉₈ = 1152.72, pupa: F₁,₉₈ = 1247.34) all showed significant reductions in duration at 28 °C (all p < 0.05). These findings provide clear guidance for optimizing laboratory rearing protocols for P. operculella by prioritizing temperature control.