Chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) has emerged as a severe invasive pest of strawberry Fragaria × ananassa Duchesne in the United States. The objective of this study was to assess the field efficacy of a biopesticide and thrips predator, Amblyseius swirskii Athias-Henriot for S. dorsalis management in field grown strawberry compared to synthetic insecticide applications that are current industry standard (spinetoram) conducted at UF/IFAS GCREC, FL during 2021-2022 and 2022-2023 in a 2-year field study. The following treatments were applied in the field: (1) biopesticide, capsicum oleoresin extract + garlic oil + canola oil application at maximum label rate; (2) predatory mite of thrips, A. swirskii released at 30 predators per plot; (3) spinetoram applied at maximum label rate; and (4) biopesticide applied 24 h before release of A. swirskii. A control plot with no insecticide or predatory mite releases was maintained. Results show that the capsicum extract can be used for management of S. dorsalis, especially during the latter stages of strawberry field season when resistance to spinetoram is high. The field performance of A. swirskii was variable and extensive research is needed to highlight factors affecting field performance of predatory mites for thrips management.

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.

Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) is an invasive pest that is popularly known as chilli thrips. This insect pest has a wide range of hosts distributed across 72 plant families, causing damage to numerous crops of great economic importance. In the Americas, it is present in the USA, Mexico, Suriname, Venezuela, Colombia, and some Caribbean Islands. Knowing the regions which have environmentally suitable conditions for the survival of this pest is important for phytosanitary monitoring and inspection. Thus, our objective was to forecast the distribution potential of S. dorsalis with a focus on the Americas. Models were produced to design this distribution, in which the environmental variables used were made available in Wordclim version 2.1. The algorithms used for the modeling were the generalized additive model (GAM), generalized linear model (GLM), maximum entropy (MAXENT), random forest (RF), and Bioclim, in addition to the ensemble, which consisted of the grouping of the algorithms used. The metrics used to evaluate the models were area over the curve (AUC), true ability statistics (TSS), and Sorensen score. All models had satisfactory results (> 0.8) for all metrics used. In North America, the model showed favorable regions on the west coast of the USA and east coast near New York. In South America, the potential distribution of the pest is significant, encompassing regions in all countries. It is concluded that S. dorsalis has suitable areas for the occurrence in the three American subcontinents and, in particular, a large part of South America.

Scirtothrips dorsalis Hood is an invasive and foliar pest of Florida blueberry that reduces plant growth by feeding on new leaf growth. A sampling plan is needed to make informed control decisions for S. dorsalis in blueberry. Fourteen blueberry fields in central Florida were surveyed in 2017 and 2018 after summer pruning to determine the spatial and temporal distribution of S. dorsalis and to develop a fixed-precision sampling plan. A sampling unit of ten blueberry shoots (with four to five leaves each) was collected from one blueberry bush at each point along a 40 × 40 m grid. Field counts of S. dorsalis varied largely ranging from zero to 1122 adults and larvae per sampling unit. Scirtothrips dorsalis had aggregated distribution that was consistent within fields and temporally stable between summers, according to Taylor\'s power law (TPL) (aggregation parameter, b = 1.57), probability distributions (56 out of 70 sampling occasions fit the negative binomial distribution), Lloyd\'s index (b > 1 in 94% occasions), and Spatial Analysis by Distance IndicEs (31% had significant clusters). The newly developed fixed-precision sampling plan required 167, 42, seven, or three sampling units to estimate a nominal mean density of 20 S. dorsalis per sampling unit with a precision of 5%, 10%, 25%, or 40%, respectively. New knowledge on S. dorsalis distribution will aid in evaluating the timing and effectiveness of control measures.

We report for the first time the detection of Scirtothrips dorsalis Hood (Thysanoptera: Thripidae) in Brazil and describe the occurrence of the thrips on leaves of ungrafted dwarf-cashew Anacardium occidentale Linnaeus 1753 (Anacardiaceae), maintained into a greenhouse, in the northeastern state of Ceará. This exotic polyphagous species listed as absent quarantine pest in the country is originated in Asia, but since the beginning of this century, it has readily dispersed despite the strict quarantine regulations currently in several countries. Individuals of S. dorsalis identified in Brazil are similar to specimens found in South Africa rather than Asia by virtue of the absence of conspicuous reticulation on the posterior half of the metanotum and the presence of complete lines of microtrichia restricted to the posterior part of the abdominal sternites. Scirtothrips dorsalis is a particularly invasive pest and its introduction represents a potential threat to various crops in Brazil, especially mango.

The mitochondrial cytochrome oxidase I gene (mtCO1) and the ribosomal internal transcribed spacer 2 region (ITS2) are among the most widely used molecular markers for insect taxonomic characterization. Three economically important species of thrips, Scirtothripsdorsalis, Thripspalmi, and Frankliniellaoccidentalis were selected to examine the extent of intragenomic variation within these two marker regions in the family Thripidae, and determine if this variation would affect the utility of markers in thrips molecular diagnostics. For each species, intragenomic (within individual) variation and intergenomic (among individuals) variation was assessed by cloning and sequencing PCR-amplified copies. Intergenomic variation was generally higher than intragenomic variation except in cases where intergenomic variation was very low, as in mtCO1 from S.dorsalis and F.occidentalis. Intragenomic variation was detected in both markers in all three of the thrips species, however, 2-3 times more intragenomic variation was observed for ITS2 than mtCO1 in both S.dorsalis and T.palmi. Furthermore, levels of intragenomic variation were low for both of the genes in F.occidentalis. In all of the three thrips species, no sex-based clustering of haplotypes was observed in either marker. Unexpected high intragenomic variation in ITS2 for two of three thrips species did not interfere with thrips diagnostics. However, caution should be taken in applying ITS2 to certain studies of S.dorsalis and T.palmi when high levels of intragenomic variation could be problematic or confounding. In such studies, mtCO1 may be a preferable marker. Possible reasons for discrepancies in intragenomic variation among genomic regions are discussed.

The development of simple and reliable pest sampling programs is needed for growers to adopt economic or aesthetic injury levels. We developed a sampling plan for monitoring chilli thrips Scirtothrips dorsalis Hood populations on KnockOut shrub roses under simulated nursery conditions. The distribution of S. dorsalis among different plant structures revealed that most adults and larvae are found on foliar terminals, when compared with buds and flowers. Based on thrips distribution, the third leaf of actively growing terminals was used to determine a sequential sampling model. Thrips had an aggregated distribution, based on Taylor\'s power law and Iwao\'s mean crowding index, with both models showing a good fit (i.e., R2 of ∼0.8 and ∼0.9, respectively). Based on these model parameters, the number of samples required to estimate populations with a 10% precision was ∼30 leaves according to Green\'s and Kuno\'s enumerative sequential sampling plans. A binomial model also estimated the proportion of infested leaf terminals as a function of insect density with an R2 value of 0.85. An additional study demonstrated that correlation between visual damage to the third leaf terminal and initial thrips populations was modeled by simple power functions. This finding suggests that a more rapid visual sampling of plant damage can be used to indirectly estimate S. dorsalis populations. Our sampling plan provides a tool to monitor S. dorsalis populations that could be used to help make management decisions for this pest in commercial nurseries.

The last 2 decades have produced a better understanding of insect-microbial associations and yielded some important opportunities for insect control. However, most of our knowledge comes from model systems. Thrips (Thysanoptera: Thripidae) have been understudied despite their global importance as invasive species, plant pests and disease vectors. Using a culture and primer independent next-generation sequencing and metagenomics pipeline, we surveyed the bacteria of the globally important pest, Scirtothrips dorsalis Hood. The most abundant bacterial phyla identified were Actinobacteria and Proteobacteria and the most abundant genera were Propionibacterium, Stenotrophomonas, and Pseudomonas. A total of 189 genera of bacteria were identified. The absence of any vertically transferred symbiont taxa commonly found in insects is consistent with other studies suggesting that thrips primarilly acquire resident microbes from their environment. This does not preclude a possible beneficial/intimate association between S. dorsalis and the dominant taxa identified and future work should determine the nature of these associations.