Abstract
The information that female insects perceive and use during oviposition site selection is complex and varies by species and ecological niche. Even in relatively unexploited niches, females interact directly and indirectly with conspecifics at oviposition sites. These interactions can take the form of host marking and re-assessment of prior oviposition sites during the decision-making process. Considerable research has focused on the niche breadth and host preference of the polyphagous invasive pest Drosophila suzukii Matsumura (Diptera: Drosophilidae), but little information exists on how conspecific signals modulate oviposition behavior. We investigated three layers of social information that female D. suzukii may use in oviposition site selection—(1) pre-existing egg density, (2) pre-existing larval occupation, and (3) host marking by adults. We found that the presence of larvae and host marking, but not egg density, influenced oviposition behavior and that the two factors interacted over time. Adult marking appeared to deter oviposition only in the presence of an unmarked substrate. These results are the first behavioral evidence for a host marking pheromone in a species of Drosophila. These findings may also help elucidate D. suzukii infestation and preference patterns within crop fields and natural areas.
Highlights
Social facilitation and the use of marking pheromones exists in some drosophilid species and true fruit flies, and recent evidence suggests that an aggregation pheromone may be used by D. suzukii to influence conspecific oviposition[29]
We found no relationship between the starting egg density and the number of new eggs deposited by D. suzukii females regardless of marking status (ANOVA, marked (Assay 1): F4,40 = 1.97, p = 0.118; unmarked (Assay 2): F4,28 = 0.533, p = 0.713; Fig. 1a,b)
Female insects have many sources of information available when choosing where to oviposit their eggs in a dynamic landscape
Summary
Social facilitation and the use of marking pheromones exists in some drosophilid species and true fruit flies, and recent evidence suggests that an aggregation pheromone may be used by D. suzukii to influence conspecific oviposition[29]. In another Drosophila species, D. melanogaster, both males and females leave aggregation pheromones on oviposition substrates, presumably in response to the competition faced within their ecological niche[30,31]. To mitigate the high costs of larval competition, several fruit feeding tephritid fly species utilize HMPs to discourage conspecific and interspecific oviposition on previously infested fruit[38,39]. Our results contribute fundamental insights into OSS in insects and offer a promising avenue of research into a potential HMP for this global pest
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