Nutritional geometry and fitness consequences in Drosophila suzukii, the Spotted-Wing Drosophila

Abstract

Since its arrival to North America less than a decade ago, the invasive Spotted-Wing Drosophila (Drosophila suzukii) has inflicted substantial economic losses on soft fruit agriculture due to its ability to oviposit into ripening fruits. More effective management approaches for this species are needed, but little is known about the factors that influence behavioral choices made by D. suzukii when selecting hosts, or the consequences that their offspring experience when developing in different environments. Using a nutritional geometry methodology, we found that the ratio of proteins-to-carbohydrates (P:C) present in media greatly influenced adult D. suzukii behavior and subsequent offspring development. Whereas adult flies showed a strong bias in their oviposition and association behaviors toward carbohydrate-rich foods, larval survival and eclosion rate were strongly dependent on protein availability. Here, we explore the preference-performance hypothesis (PPH), in which females are predicted to oviposit on medias that provide the greatest offspring benefits, in regard to its relevance in D. suzukii behavior and consequences for management. Our results provide valuable insight into the ecology and evolution of this species that may hopefully lead to more effective management strategies.

Keywords: Drosophila suzukii; Spotted‐Wing Drosophila; carbohydrates; diet; nutrition; nutritional geometry; protein.

Figure 1

Oviposition preference among medias differing in protein: carbohydrate (P:C) ratio in choice environments. Boxplots of numbers of eggs female Drosophila suzukii laid on each of the eight different P:C medias in each choice chamber (80 chambers in total) over a 25‐hr period. The box encloses values between the first and third quartiles of the data (the interquartile range (IQR)), whereas the horizontal bar within the box indicates the median. Whiskers extend from the box to largest/smallest values that are within 1.5 ×  the IQR of the box. Values outside that range are outliers and are indicated by circles. Boxplots that are not sharing a letter have significantly different means

Figure 2

Larval survivorship on medias differing in protein: carbohydrate (P:C) ratio. Boxplots of proportion of flies that eclosed as adults within 22 days following the transfer of a standardized number of eggs (20) into vials containing artificial media a) with antimicrobials and b) without antimicrobials. The box encloses values between the first and third quartiles of the data (the interquartile range [IQR]), whereas the horizontal bar within the box indicates the median. Whiskers extend from the box to largest/smallest values that are within 1.5 ×  the IQR of the box. Values outside that range are outliers and are indicated by circles. Boxplots that are not sharing a letter have significantly different means

Figure 3

Predicted number of surviving adults on medias differing in protein: carbohydrate (P:C) ratio. Boxplot of number of adults predicted to eclose on substrates of differing P:C ratios based on oviposition rates in a choice environment and survivorship values derived from the assays in media, a) inhibited microbial growth and b) supported microbial growth. In both analyses, there were significant differences in the number of expected offspring eclosing from each media type (Kruskal–Wallis tests: a: χ² = 356.01, df = 7, p < .0001; b: χ² = 476.45, df = 7, p < .001). The box encloses values between the first and third quartiles of the data (the interquartile range [IQR]), whereas the horizontal bar within the box indicates the median. Whiskers extend from the box to largest/smallest values that are within 1.5 ×  the IQR of the box. Values outside that range are outliers and are indicated by circles. Boxplots that are not sharing a letter have significantly different medians