Phenology of spotted wing drosophila in the San Joaquin Valley varies by season, crop and nearby vegetation

Abstract

The spotted wing drosophila, first detected in California in 2008, has become a major insect pest in caneberries and sweet cherries, causing commercial crop losses. Managing it is challenging because it has many other hosts, including riparian and backyard fruit plantings, and it increases rapidly, with generations overlapping one another. In our study we monitored trap captures in two parts of the San Joaquin Valley, within sweet cherry orchards and in nearby locations. Captures of adult flies showed two main periods of activity -spring and fall -and low captures in the winter (except for citrus and evergreen riparian areas) and summer. On many occasions during the year, trap captures were higher outside of the cherry orchards than within them. Additionally, early in the season, when decisions about control programs are being made, the sex ratio of captured flies in cherries was strongly female-biased. The results suggest that during the weeks leading up to harvest growers should experiment by placing traps in different environments surrounding their orchards to determine SWD activity and potential pest pressure locally, and monitor for both male and female flies.

Influences of blackberry margins on population dynamics of Drosophila suzukii and grape infestation in adjacent vineyards

“…However, the effect of margin type was quite small and inconsistent across seasonal periods (Figure 3), with the proportion of females in trap captures being slightly higher in NH than in BB sites at distinct seasonal periods. The sex ratio of D. suzukii flies shifted towards male-biased and back to female-biased captures throughout the season, which is partly in line with previous studies from other regions reporting a skewed sex ratio (Haviland et al, 2016;Rossi-Stacconi et al, 2016;Tait et al, 2018). The female-biased sex ratio particularly at the beginning and the end of the year may be related to a higher winter survival or longevity of females Thistlewood et al, 2018;Zerulla et al, 2015).…”

“…Seasonal changes in host plant phenology may entail strong variation in the availability of oviposition sites (fruits) and feeding sites (microorganisms on leaves), shelter and overwintering sites (evergreen leaves and plant architecture) for D. suzukii (Harris, Hamby, Wilson, & Zalom, ; Haviland, Caprile, Rill, Hamby, & Grant, ; Tonina, Mori, Sancassani, Dall'Ara, & Marini, ; Wang et al, ) and thus crucially impact the population dynamics of the fly assessed with the three applied monitoring methods. In order to account for this variation, we recorded the fruiting period, that is, presence and ripening stage of blackberry and grapefruits, as well as the status of foliage, that is, presence/absence of leaves, fresh/old leaves, from cw 29 (2016) to cw 9 (2017).…”

Phenology of Drosophila species across a temperate growing season and implications for behavior

“…suzukii . The pattern is repeated in the San Joaquin Valley, California, where abundance is locally high by fruit type in November through June, but the flies are not attracted to bait in July through October [90].…”

Temporal Dynamics of Host Use by Drosophila suzukii in California’s San Joaquin Valley: Implications for Area-Wide Pest Management

“…Since then, damaging populations have been recorded from cherries, cranberries, mulberries, raspberries and strawberries, mainly in the coastal or northern California fruit growing regions with relatively mild summer [42,43,44,45]. In comparison, California’s interior San Joaquin Valley has hotter summers and colder winters [46], and while D. suzukii is collected in cherry, citrus, fig, grape, kiwi, mulberry, nectarine, peach, persimmon, plum and pomegranate as well as in non-crop habitats surrounding the orchards [39,47,48], reported crop damage has been mainly on cherries [48]. Adult fly captures show two main periods of activity—spring and fall—and low captures in winter (except for evergreen riparian areas) and summer [39,47,48].…”