Evaluation of Strawberry Sap Beetle (Coleoptera: Nitidulidae) Use of Habitats Surrounding Strawberry Plantings as Food Resources and Overwintering Sites

The matrix of strawberry and alternate host crops, wooded areas, and uncultivated sections that comprises a farm landscape provides not only food resources but also habitat in both a spatial and temporal context. Reports of the strawberry sap beetle as a pest in strawberry in the northeastern United States have increased along with a trend to produce a wider diversity of fruit crops on individual farms. The three objectives of this study focused on determining which, if any, habitats outside strawberry plantings are important to consider when developing control strategies for strawberry sap beetles. First, sampling of wooded areas and multiple crops showed that strawberry sap beetles overwinter not only in wooded areas but also in blueberry and raspberry. No overwintering beetles were found in strawberry. Second, up to a 70-fold increase in mean number of strawberry sap beetles in a no-choice food source experiment indicated that considerable reproduction can occur on blueberry, cherry, raspberry, and strawberry. Third, sampling summer-bearing raspberry, peach, blueberry, and cherry in 2004 and 2005 confirmed that beetles were present, often in high densities (0.1-108.5 strawberry sap beetles/m2), in commercial fields with fruit or vegetable material on the ground. In summary, the beetles are able to feed, complete development, and overwinter in habitats other than strawberry. An effective integrated pest management program to control strawberry sap beetles will need to consider the type of habitat surrounding strawberry field

Evaluation of Cultural Practices for Potential to Control Strawberry Sap Beetle (Coleoptera: Nitidulidae)

Strawberry sap beetle, Stelidota geminata (Say) (Coleoptera: Nitidulidae), adults and larvae feed on and contaminate marketable strawberry (Fragaria L.) fruit. The beetle is a serious pest in the northeastern United States, with growers in multiple states reporting closing fields for picking prematurely due to fruit damage. Three options were evaluated for potential to reduce strawberry sap beetle populations. First, the influence of plant structure on accessibility of fruit in different strawberry cultivars to strawberry sap beetle was assessed by modifying plant structure and exposing caged plants to strawberry sap beetle adults. Severity of damage to berries staked up off the ground was similar to damage to those fruit contacting the soil, showing that adults will damage fruit held off the ground. Second, baited traps were placed at three distances into strawberry fields to determine whether overwintered beetles enter strawberry fields gradually. Adult beetles were first caught in the strawberries ≈19 d after occurring in traps placed along edges of adjacent wooded areas. The beetles arrived during the same sampling interval in traps at all distances into the fields, indicating that a border spray is unlikely to adequately control strawberry sap beetle. Third, the number of strawberry sap beetle emerging from strawberry for 5 wk after tilling and narrowing of plant rows was compared in plots renovated immediately at the end of harvest and in plots where renovation was delayed by 1 wk. In the 2-yr study, year and not treatment was the primary factor affecting the total number of emerging strawberry sap beetle. Overall, limited potential exists to reduce strawberry sap beetle populations by choosing cultivars with a particular plant structure, applying insecticide as a border spray, or modifying time of field renovatio

Effects of Cane Emergence Time, Bending, and Defoliation on Flowering and Yield in Primocane-Fruiting Blackberry

Primocane-fruiting (PF) blackberries are adaptable to different production systems. To increase yields in PF blackberries, their primocanes are typically tipped or topped in summer to encourage branch formation from axillary buds below the cut. In this study, we determined in PF ‘Prime-Ark® Traveler’ whether early emerging primocanes were more productive than those that emerged later in the season, and the effect of primocane bending and defoliation on flowering. The primocanes that emerged in April produced 64% more flower shoots than those that emerged after May. Also, these findings indicate the alternative primocane management practices of selecting the early emerging primocanes and bending to orient primocanes horizontally, and leaf removal to increase budbreak and flower shoot emergence. The present work contributes toward a better understanding of primocane emergence time and orientation–flowering relations, and how these factors mediate crop performance of PF blackberry

Seasonal Population of Drosophila suzukii (Diptera: Drosophilidae) and Pesticide Use Pattern after Its Invasion in Caneberry Crops in Pennsylvania (USA)

Drosophila suzukii (Diptera: Drosophilidae) is a major invasive pest of caneberries (e.g., blackberries and raspberries) and other thin-skinned fruit crops. In recent years, it has been reported as an economically important fruit pest in many countries. In caneberries, the timely detection and management of invasive insect pests such as D. suzukii is important to maintain profitability and avoid fruit export restriction. Invasions by such new pest species in commercial crop production often changes pesticide use patterns and frequency as growers try to control pest populations on their farms. In this study, we examined the seasonal population of D. suzukii and pesticide use patterns before and after D. suzukii invasion in primocane-fruiting raspberry and floricane-fruiting blackberry crop production in Pennsylvania. The results of seasonal monitoring conducted over two years showed higher populations of D. suzukii fruit flies during the settle period. The evaluation of crop-specific pesticide programs showed an increase in pesticide use frequency compared to the crop season before D. suzukii invasion in the blackberry planting. Similarly, over a five-fold increase in pesticide application was recorded in the raspberry planting in the year following invasion. The implications of increased pesticide use patterns in blackberry and raspberry production are discussed

Widespread establishment of adventive populations of Leptopilina japonica (Hymenoptera, Figitidae) in North America and development of a multiplex PCR assay to identify key parasitoids of Drosophila suzukii (Diptera, Drosophilidae)

In recent years, there has been an increase in the adventive establishment and spread of parasitoid wasps outside of their native range. However, lack of taxonomic tools can hinder the efficient screening of field-collected samples to document the establishment and range expansion of parasitoids on continent-wide geographic scales. Here we report that Leptopilina japonica (Hymenoptera, Figitidae), a parasitoid of the globally invasive fruit pest Drosophila suzukii (Diptera, Drosophilidae), is now widespread in much of North America despite not having been intentionally introduced. Surveys in 2022 using a variety of methods detected L. japonica in 10 of 11 surveyed USA States and one Canadian Province where it was not previously known to occur. In most surveys, L. japonica was the most common species of D. suzukii parasitoid found. The surveys also resulted in the detection of Ganaspis cf. brasiliensis (Hymenoptera, Figitidae), the recently-released biological control agent of D. suzukii, in six USA States where it had not previously been found. These new detections are likely a result of intentional biological control introductions rather than spread of adventive populations. A species-specific multiplex PCR assay was developed as a rapid, accurate and cost-effective method to distinguish L. japonica, G. cf. brasiliensis, the closely-related cosmopolitan parasitoid Leptopilina heterotoma (Hymenoptera, Figitidae) and other native parasitoid species. This dataset and the associated molecular tools will facilitate future studies of the spread and ecological impacts of these introduced parasitoids on multiple continents

Widespread establishment of adventive populations of Leptopilina japonica (Hymenoptera, Figitidae) in North America and development of a multiplex PCR assay to identify key parasitoids of Drosophila suzukii (Diptera, Drosophilidae)

In recent years, there has been an increase in the adventive establishment and spread of parasitoid wasps outside of their native range. However, lack of taxonomic tools can hinder the efficient screening of field-collected samples to document the establishment and range expansion of parasitoids on continent-wide geographic scales. Here we report that Leptopilina japonica (Hymenoptera, Figitidae), a parasitoid of the globally invasive fruit pest Drosophila suzukii (Diptera, Drosophilidae), is now widespread in much of North America despite not having been intentionally introduced. Surveys in 2022 using a variety of methods detected L. japonica in 10 of 11 surveyed USA States and one Canadian Province where it was not previously known to occur. In most surveys, L. japonica was the most common species of D. suzukii parasitoid found. The surveys also resulted in the detection of Ganaspis cf. brasiliensis (Hymenoptera, Figitidae), the recently-released biological control agent of D. suzukii, in six USA States where it had not previously been found. These new detections are likely a result of intentional biological control introductions rather than spread of adventive populations. A species-specific multiplex PCR assay was developed as a rapid, accurate and cost-effective method to distinguish L. japonica, G. cf. brasiliensis, the closely-related cosmopolitan parasitoid Leptopilina heterotoma (Hymenoptera, Figitidae) and other native parasitoid species. This dataset and the associated molecular tools will facilitate future studies of the spread and ecological impacts of these introduced parasitoids on multiple continents