Simple Summary The tomato leafminer is a major pest that damages tomato plants worldwide. Its young stage, the pupa, often lives in the soil. This study examined whether changing soil wetness could be used to control this pest. We tested how well pupae survive and turn into adult moths in soils ranging from completely dry to fully waterlogged. We found that the insects strongly preferred slightly dry soil. Most adult moths successfully emerged when soil moisture was around twenty to forty percent. However, in very dry or very wet soils, many pupae died. In waterlogged soil, all the pupae died within days. Most insects also stayed in the very top layer of soil. These findings suggest that farmers could help control this pest by briefly wetting the soil surface when the insect is entering the pupal stage. This method could reduce the need for chemical sprays, offering a more natural way to protect crops and support sustainable farming. The tomato leafminer, Tuta absoluta (Meyrick), is a globally invasive lepidopteran pest whose pupal stage commonly occurs within or at the soil surface. Soil moisture is a primary abiotic driver shaping soil microhabitats and therefore likely to influence pupation behavior, pupal survival and emergence. We quantified how six controlled soil moisture levels (0%, 20%, 40%, 60%, 80% and 100% saturation, wet-weight basis) affect pupation site selection, pupation depth, pupal survival and emergence under laboratory conditions, and performed a four-choice moisture preference assay. Larvae preferentially selected shallow soil layers (0–1 cm) and showed a marked behavioral preference for relatively low moisture (20–40%); maximum emergence (83%) occurred at 20% moisture. Both extreme drought (0%) and high saturation (≥80%) strongly reduced survival and emergence. These unimodal responses indicate that soil moisture constrains T. absoluta recruitment and may be exploited as a target for ecologically based control. The results provide a quantitative basis for soil-moisture-oriented IPM tactics and identify field validations and formulation/timing optimizations required to translate laboratory findings into practice.
