Screening for control of adult male red clover casebearer moth

Moths were collected from a red clover paddocks in mid-Canterbury on 12 December 2017. These were held in vented cages in a shade house. Humidity in the cages was kept elevated using tissue moistened with tap water.

On 13 December 2017, moths were treated with field rates of Mavrik® (a.i. 240 g/l tau-fluvalinate), Lorsban (a.i. 500 g/l chlorpyrifos), Karate Zeon® (a.i. 250 g/l lambda cyhalothrin) and Exirel® (a.i. 100 g/l cyantraniliprole. Control treatments were water only and water plus adjuvant. Each treatment was replicated eight times with 7-8 moths in each dish.

Moths were placed into 150 mm Petri dishes lined with filter paper and confined with a coarse metal mesh lid. Treatments were applied using a knapsack sprayer. At the completion of application, dishes were transferred to a controlled environment room (18^oC, natural light) where the mortality assessments were made. At the completion of the mortality assessments, dishes were sprayed with tap water and loosely covered with plastic lids.

Assessment took place approximately 4.5, 24 and 48 hours following treatment.

Results

There was rapid mortality using Mavrik®, Karate Zeon® and Lorsban™ 50EC following application as evidenced by high mortality after only 4.5 hours following treatment (Table 1).

Table 1 Mortality of adult male red clover casebearer moth after treatment with selected insecticides. Mortality corrected using Henderson-Tiltons formula

* Results subject to change following further analysis

The results provide a promising indication that some of the insecticides currently used provide effective control of red clover casebearer moth. However, the provisos are that in the field, adults may not receive a direct application due to location in the foliage. In addition, female moths may be less mobile and therefore not come into contact with residues.

Always consult your agrichemical adviser before implementing control measures and practice bee-safe application techniques.