Solenopsis mealybug - the new cotton IPM enforcer

Abstract

The solenopsis mealybug (Phenacoccus solenopsis) is widespread throughout QLD and in 2017 was confirmed as being present in the cotton growing areas in the Gwydir and Namoi valleys of northern NSW. Solenopsis mealybug adults are 3-4 mm long and have two characteristic dark longitudinal bare spots across their thorax and abdomen (look like black spots).
Solenopsis is a high priority pest for the cotton industry for several reasons: (i) it causes direct yield loss, plant damage and death, typically in the form of patches or dead plants or ‘hot spots’ (ii) populations of solenopsis are easily flared by spray practices targeting other pests such as mirids and mites which require frequent control in Bollgard III cotton production systems; (iii) it is very easily dispersed by wind and rain, and through the movement of infested plants, farm machinery, vehicles and on clothing and footwear; (iv) it’s population dynamics are highly unpredictable.
Weed and volunteer plant control, farm hygiene practices and the conservation of naturally occurring beneficial insects (lacewings, Cryptolaemus, 3-banded ladybird, Aenasius wasp) are key elements of successful solenopsis mealybugs control in cotton.
Research done over the last three years by the Queensland Department of Agriculture and Fisheries staff in Toowoomba and Emerald has resulted in the identification of sulfoxaflor, buprofezin and spirotetramat, new generation, IPM-compatible insecticidal compounds with efficacy on solenopsis mealybugs. Spray Oils were also identified as having a significant suppressive effect.
The cotton industry is currently working with registrants towards permit/registrations.