The strawberry crop endures economic losses due to feeding injury from a number of phytophagous arthropod pests. A number of invasive pests have posed challenges to crop protection techniques in the strawberry cropping system recently. It is increasingly evident that sole reliance on chemical control options is not sustainable. In this review, current challenges and advances in integrated pest management of various strawberry pests are presented. Key pests discussed include thrips, mites, lygus bug, spotted wing drosophila, seed bug, weevils, aphids, whiteflies, and armyworms. Several integrated pest management techniques that include use of intercropping, resistant cultivars, irradiation with gamma rays, use of spectral sensitivity of pests, biological control agents and natural enemies, and biorational pesticides have recently been reported to be useful in managing the various strawberry pests. With the increase in world production of strawberry, several techniques will be necessary to manage the pest complex of strawberry.
Chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) is a major, economically important, and recent invasive pest of strawberries and other horticultural crops in United States. Several conventional insecticides are used for S. dorsalis management, and resistance development threatens loss of few available tools. Hence, our objectives were to: (1) determine the susceptibility of S. dorsalis to commonly used conventional insecticides: spinetoram, acetamiprid, cyantraniliprole and bifenthrin, and (2) establish LC50 and LC90 dosages for spinetoram against S. dorsalis. Sampling of S. dorsalis populations was conducted twice in seven strawberry fields in Florida during the strawberry field season between 2019 and 2020. Leaf‐disc bioassays were performed with field collected populations along with a susceptible 2‐year‐old laboratory culture of S. dorsalis. Overall, at highest recommended rate the percent mortality of late season S. dorsalis populations from five out of seven collection sites was lower (~41%) than average mortality observed with early season populations (~72%). Populations from at least four out of seven sampling sites exhibited significantly lower mortality than the laboratory susceptible culture in late season. The LC50 and LC90 values for spinetoram for the susceptible laboratory population were 0.026 and 8.64 ppm, respectively. On the other hand, LC50 values of field collected populations to spinetoram varied with resistance ratios ranging from 6 to 269 fold as compared against the laboratory strain. Our results suggest that susceptibility of S. dorsalis to commonly used insecticides in strawberries varies significantly between early and late season populations within the same crop season. The efficacy of bifenthrin against S. dorsalis was particularly low (~ reduced to half in late season), especially among field collected populations. Our results indicate an urgent need to incorporate other pest management strategies, as well as effective rotation programs to reduce selection for resistance among populations of S. dorsalis in strawberry production.
This publication provides current management practices for chilli thrips in both conventional and organic strawberries as a guide for Extension agents and growers.
Given the recent invasion of Scirtothrips dorsalis Hood in North America, there is limited information regarding their distribution and population dynamics in cultivated small fruit crops. Therefore, we investigated the spatial and temporal distribution of S. dorsalis and their natural enemies in commercially produced strawberry fields in Florida. During 2 consecutive strawberry production seasons, 4 and 6 geographically separated strawberry fields were sampled and were divided into grids with 30–40 sampling points per field. At each sampling point, 4–5 leaf and flower samples were collected, and sticky traps were deployed. We quantified the occurrence of S. dorsalis as well as potential natural enemies, including Orius spp., Geocoris spp., and other predators such as long-legged flies. During both years, most of the S. dorsalis and natural enemies were found on field borders, and counts progressively diminished further into the interiors of plots and away from field edges. Cluster and outlier analysis revealed that S. dorsalis formed statistically significant clusters and that these “hot spots” remained in the same general locations throughout the season. There was a strong relationship between the occurrence of natural enemies and the presence of S. dorsalis, but the number of natural enemies was generally low compared to S. dorsalis. Our results indicate that targeting field borders for chemical control or planting strawberries away from natural areas containing potential alternative hosts for thrips may be an effective strategy for reducing agricultural inputs; however, future field assessments are needed to determine if these methods could replace the treatment of entire fields.