Citrus thrips, Scirtothrips aurantii (Thysanoptera: Thripidae), damage and infestation in the presence of molasses

• We tested the effect of molasses on Scitothrips aurantii in citrus orchards.
• Sticky traps, scouting and damage evaluation revealed no significant differences.
• Molasses does not promote secondary infestation by S. aurantii.
• Molasses should be applied with CrleGV applications.

The Cryptophlebia leucotreta granulovirus (CrleGV) is used for control of false codling moth (FCM), Thaumatotibia leucotreta (Lepidoptera: Tortricidae), on citrus in South Africa. The virus is applied with molasses, which has been shown to improve its efficacy against FCM. However, little is known about the influence of molasses used as a spray additive on citrus thrips, Scirtothrips aurantii, a major cosmetic pest of citrus fruit. The aim of this study was to determine if molasses influences the occurrence of, and damage to fruit, caused by Scitothrips aurantii. A field trial was conducted that included trees sprayed with different molasses concentrations and control trees at four sites in the Eastern Cape Province of South Africa. Scirtothrips aurantii population sizes were quantified through monitoring with yellow sticky traps, a scouting protocol and a damage assessment after application of the respective treatments. Numbers of adult S. aurantii caught with yellow sticky traps were high for all study sites but there was no significant difference among treatments within sites (P > 0.05). Scouting also revealed high S. aurantii numbers combined with low numbers of predatory mites. However, there was no significant difference in the number of adult or larval S. aurantii present on fruit among treatments within sites (P > 0.05). A damage evaluation, conducted one month after the study, showed no significant difference among treatments (P > 0.05). This study has shown that the inclusion of molasses, applied as a medium cover spray, does not result in increased S. aurantii infestation or damage and can thus be included in the CrleGV applications.