Effect of erythritol formulation on the mortality, fecundity and physiological excretion in Drosophila suzukii

Authors: TANG, SIEW BEE - Oregon State University; Lee, Jana; JUNG, JIN-KYO - National Institute Of Crop Science - Korea; Choi, Man-Yeon

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2017
Publication Date: 7/29/2017
Citation: Tang, S., Lee, J.C., Jung, J., Choi, M.Y. 2017. Effect of erythritol formulation on the mortality, fecundity and physiological excretion in Drosophila suzukii. Journal of Insect Physiology. 101:178-184. https://doi.org/10.1016/j.jinsphys.2017.07.015.
DOI: https://doi.org/10.1016/j.jinsphys.2017.07.015

Interpretive Summary: Spotted wing drosophila (SWD), Drosophila suzukii, is a severe invasive pest attacking a wide range a wide range of small fruits including almost all cherry cultivars. SWD exhibits a broad range of almost all varieties of small fruits including blackberries, blueberries, cherries, peaches, raspberries, strawberries, and grapes. Since the first outbreak in U.S. 2008 the distribution of SWD is rapidly expanding across the U.S., Canada and Europe. The estimated economic impact from crop yield loss, drop in market value, and higher management cost is almost $1 billion in U.S. alone, and increasing every year. To replace or reduce the use of chemical insecticides, currently alternative options are being developed, but there are still many critical gaps to be implemented against SWD in field. Scientists from USDA-ARS and Oregon State University in Corvallis, OR studied effect of erythritol formulation on the mortality, fecundity and physiological excretion in Drosophila suzukii. The study discovered effects of sucrose/erythritol combinations on spotted wing drosophila with blueberries and blueberry bushes in the lab and greenhouse. They found the fly survival with 0.5M sucrose/2M erythritol was lowest for 7 days. They also examined presence of erythritol in the hemolymph of the fly. Erythritol was also found from the frass in the same fly ingested erythritol. The result indicates that erythritol might be directly transported from the midgut without being metabolized and stored, but is accumulated in the hemolymph which in turn elevates the osmotic pressure in the fly hemolymph. From this study we suggest the sucrose/erythritol combination would be more effective than erythritol alone because the combination tastes sweeter to elicit more feeding. This erythritol formulation can be a potential insecticide used alone or as a delivery agent combined with conventional or biological insecticides to enhance their efficacy.

Technical Abstract: Previously, we studied various combinations of non-nutritive sugars including erythritol and erythrose having a potentially insecticidal effect on Drosophila suzukii. The study suggested two potential physiological changes causing fly mortality: 1) starvation from the feeding of non-metabolizable erythritol and erythrose; 2) abnormal osmotic pressure increased in the hemolymph with erythritol transported from the midgut. In the present study, effects of these combinations of sucrose/erythritol were applied to blueberries and monitored for impact on fly mortality and fecundity in the lab and greenhouse. In the lab, two sucrose/erythritol formulations (0.5M sucrose/2M erythritol, 1M sucrose/2M erythritol) resulted in the highest mortality and the lowest fecundity among D. suzukii adults. Two formulations, therefore, were selected for further evaluation with blueberry bushes and fruits in the greenhouse; fly survival with 0.5M sucrose/2M erythritol was significantly lower than 1M sucrose/2M erythritol for 7 days. Unlike the smaller container, mortality occurred faster in the greenhouse probably because flies moved more in the bigger cage accelerating the exhaustion of energetic reserves in the body. We examined presence of erythritol in the hemolymph and frass to determine the nutritional metabolism and absorption of erythritol in D. suzukii. Unlike sucrose, a large amount of erythritol was observed in the hemolymph of the fly ingested 0.5M sucrose/0.5M erythritol. Erythritol was also found in the frass in the same fly. The results imply that erythritol might be directly transported from the midgut without being metabolized and stored, but is accumulated in the hemolymph which in turn elevates the osmotic pressure in the fly hemolymph. To develop this novel control application for growers, the mode of action of erythritol, and its toxicity on non-target insects need to be explored in future.