Abstract
We examined the effect of relative humidity on mortality during the pupal stage (prepupa and pupa) of Thrips palmi (Thysanoptera: Thripidae) under laboratory conditions. Mortality from the prepupal stage to adulthood decreased with increasing relative humidity. We compared the mortalities under 3 experimental treatments (control; upperside treatment, prepupae were released on filter paper; underside treatment, prepupae were covered with filter paper) at various relative humidities (58, 78, 82, 86, 88, 93 and 98%). The mortality under every treatment at 58% relative humidity was 100%. Except at 58 and 93% relative humidities, the mortalities under the underside treatment were lower than the other treatments. Differences in mortality among all 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 both humidity and underside treatment had significant negative effects on mortality. Individuals released in the upperside treatment moved at higher rates within a day from the release than those in the underside treatment.
