Implications of sub-lethal rates of insecticides and daily time of application on Drosophila suzukii lifecycle

Abstract

The circadian clock is responsible for time keeping within an organism and influences not only behavioural patterns, but also physiological rhythms including toxin susceptibility. Drosophila suzukii Matsumura is a global horticultural pest, and identifying rhythms in insecticide susceptibility could contribute to improving integrated pest management practices. To determine whether time of application influences mortality, LC50 rates of cyantraniliprole, lambda-cyhalothrin, pyrethrum and spinosad were applied to groups of adult D. suzukii at two different times of day. Insecticides were directly applied using a benchtop sprayer. We found no influence of time on mortality or oviposition for any of the four insecticides applied. However, several discoveries were made regarding the impact of sub-lethal and lethal rates on D. suzukii mortality, oviposition and offspring survival over time. In most cases, all surviving females recovered from insecticide rates, and laid the same number of eggs as females treated with the water control. Seven days after application, females that were treated with the field rate of spinosad laid the same number of eggs as the control. The lowest rate of cyantraniliprole resulted in more eggs being laid, initially, with no negative impact on survival of eggs through to adult emergence. However, there were transgenerational impacts of egg to adult survival when parents were treated with sub-lethal rates of spinosad and lambda-cyhalothrin. Although no impact of daily phase of application was detected within this assay, the information surrounding how D. suzukii interacts with lethal and sub-lethal rates of insecticides is of great importance, especially for the resistance management of D. suzukii.

Insecticide Control of Drosophila suzukii in Commercial Sweet Cherry Crops under Cladding

“…The use of cladding might mitigate insecticide resistance build-up as it may prolong the time post-spraying that products are effective. The extended time of effectiveness would reduce the chances that flies will come into contact with degraded sub-lethal pesticide deposits [24]. This, in combination with other IPM controls, including crop hygiene, exclusion mesh, and tightly timed picking, should reduce and prevent damage caused by D. suzukii and avoid resistance developing when the need to use plant protection products is required.…”

“…Several classes of insecticide provide acceptable control of D. suzukii in laboratory and field trials. These include organophosphates, spinosyns, and pyrethroids [20,21,22,23,24]. Additional, less effective products providing shorter periods of protection have also been investigated.…”

Insecticidal and oviposition deterrent effects of essential oils of Baccharis spp. and histological assessment against Drosophila suzukii (Diptera: Drosophilidae)

“…Most insecticides used to control D. suzukii act on the AChE receptors or the sodium 23 – 25 , 41 , 57 , 58 . Products that use a different mode of action can thus help avoid the emergence of resistance to such compounds 27 , 28 .…”

The use of light spectrum blocking films to reduce populations of Drosophila suzukii Matsumura in fruit crops

“…Potentially a more effective strategy would be to incorporate the claddings as part of an integrated pest management approach including repellents, to further inhibit D. suzukii entering crops 56 , 57 , and attractants where semiochemical based baits are placed outside the crop to intercept and further reduce immigration into the cropping area 58 . This could have significant consequences for reducing the need for chemical plant protection products in fruit crops and the reduction of future insecticide resistance 59 , 60 .…”