Influences of relative humidity on mortality during the pupal stage of Thrips palmi (Thysanoptera; Thripidae)

We examined the effect of relative humidity on mortality during the pupal s tage (prepupa and pupa) of Thrips palmi (Thysanoptera: Thripidae) under lab oratory conditions. Mortality from the prepupal stage to adulthood decrease d with increasing relative humidity. We compared the mortalities under 3 ex perimental treatments (control; upperside treatment, prepupae were released on filter paper; underside treatment, prepupae were covered with filter pa per) at various relative humidities (58, 78, 82, 86, 88, 93 and 98%). The m ortality under every treatment at 58% relative humidity was 100%. Except at 58 and 93% relative humidities, the mortalities under the underside treatm ent were lower than the other treatments. Differences in mortality among al l three treatments were found at 82 and 86% relative humidities. At 88, 93 and 98% relative humidities, however, no differences in mortality among the three treatments were found. Logistic regression analysis revealed that bo th humidity and underside treatment had significant negative effects on mor tality. Individuals released in the upperside treatment moved at higher rat es within a day from the release than those in the underside treatment.