Chilli thrips is a foliar pest of strawberry and blueberry causing feeding injury to new growth leading to stunted plant growth and reduced yield. Currently, repeated insecticide applications are made to manage this pest, however, with limited information on the thresholds and sampling techniques, control decisions made to manage this pest might be inaccurate. Thus, the goal of my Ph.D. was to develop a comprehensive sequential sampling plan in strawberry and a fixed-precision sampling plan in blueberry to improve the monitoring and decision making of chilli thrips and possibly reduce unnecessary insecticide applications in these berry crops.
Greenhouse and field-plot studies showed that chilli thrips move slowly from initially infested to adjacent plants once they arrive in the newly transplanted strawberry fields, providing a significant window for management actions to occur until the crop loss becomes severe. In a separate two-year field-plot study, we found that actively growing strawberry plants were able to compensate for the feeding injury caused by initial five, 10, or 20 chilli thrips adults per plant (one, two, or four adults per strawberry trifoliate), when treated with reduced-risk spinetoram, two weeks after the initial infestation compared to when treated four days after the infestation, with no reduction in plant canopy area, fresh plant biomass, and marketable yield of strawberry. This means initial insecticide application can be delayed for two weeks if the chilli thrips population is below an action threshold population. An action threshold of two adults or larvae per strawberry trifoliate was established in strawberry after relating feeding injury with chilli thrips densities in field cage studies. The action threshold was associated with a 10-30% plant injury, an injury level a plant seems to tolerate. Furthermore, 10 and 14 commercial strawberry and blueberry fields were surveyed, respectively, for chilli thrips by collecting leaf samples for two consecutive seasons to assess the spatio-temporal distribution of chilli thrips. Spatial and non-spatial models such as Taylor’s power law, probability distributions, Lloyd’s index, and Spatial Analysis by Distance IndicEs showed an aggregated distribution of chilli thrips within strawberry and blueberry fields. An action threshold-based sequential sampling plan of chilli thrips was developed for strawberry which requires a minimum of four sampling units (one sampling unit = 10 strawberry trifoliates) and a maximum of 27 sampling units to make a control decision. If a decision that no action is necessary is made, it is recommended to resample the field in 14 days. Furthermore, a fixed-precision sampling plan of chilli thrips was developed for blueberry which requires seven sampling units (one sampling unit = 10 young blueberry shoots with four to five leaves each) to estimate a nominal field mean density of 20 chilli thrips per sampling unit for an area of 2-6 hectares. Aggregations of chilli thrips remained stable over time allowing previous sampling sites to be revisited for resampling both in strawberry and blueberry fields. Further research is needed to incorporate population growth model into the management of this pest since cooler nights during early strawberry season seem to affect the growth and survival of chilli thrips. Overall, the impact of chilli thrips in strawberry is likely to increase in future season as early season production is favored but using accurate sampling methods and judicious insecticide applications coupled with ongoing chilli thrips research in Florida berry crops will help producers reduce input costs and remain profitable in an increasingly competitive market.
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This is my personal blog about our hiking in Raven Rock State Park. It took us around one hour to drive to the park from Morrisville, NC. Because of the limited parking space and COVID-19 guidelines, there was a long line of vehicle to enter the park and we got in after waiting for around one hour. Of course, we were cautious and followed social distancing guidelines. We hiked along Cambell Creek Loop Trail which is moderate and 4.5 miles long and took us around three hours to hike. General information about the park Raven Rock State Park is located in Harnett County, NC 40 miles southwest of Raleigh expanding in an area of 4,800 acres. Named after the 'ravens' that roosted over a 150-foot crystalline rock structure, Raven Rock is famous for frequent hiking destinations such as the Cape Fear River, Lanier Falls, and the Fish Traps rapids that are accessible through miles of hiking trails with a total of 12 trails that are easy to moderate in difficulty and 0.2 to 6.6 miles long. Along the way to the rock are steep terrain, native mountain laurels, rhododendron thickets, and tumbling creeks. With 26 miles of hiking, 6.6 miles of biking and 8 miles of horseback riding trails, visitors also have access to paddling, fishing, pickniking, and backpacking and paddle-in sites in Raven Rock State Park. This park also features amenities such as amphitheater, auditorium, classroom, picnic shelter, visitor center, exhibit, kids track trail, and horse trailer parking out of which longleaf loop trail, two tables inside the picnic shelter, one of the grills at the picnic shelter, the visitor center, parking, and restrooms are wheelchair accessible. Natural resources Topography and vegetation The topography are floodplains, river bluffs, and flat and dry uplands. Big tres such as river birch, beech and sycamore are found along floodplains. Mountain laurel, rhododendron, elm, and red maple trees are along river bluffs. And, pine, oak/hickory, sourwood, dogwood, and blueberry are found along flat and dry uplands. Aquatic invertebrates and reptiles Aquatic invertebrates such as salamanders are found along the river bluffs. Spotted turtles and larger turtles such as the yellowbelly slider and the snapping turtle live in streams and rivers. Lizards such as the Carolina anole, fence lizard, and skink inhabit the forest. And, harmless snakes such as northern water snake, rat snake, and the eastern hognose snake are found in the park along with rarely occuring the venomous copperhead. Birds and mammals At the peak of the season, visitors get sightings of as many as 20 species of warblers, wood ducks, hawks, owls and woodpeckers. Mammals include white-tailed deer, eastern cottontails, weasels, raccoons, mice, shrews, beavers, muskrats, and bats. Insects Links for Insect Orders known for Raven Rock State Park. COLEOPTERA - Beetles DIPTERA - Flies EPHEMEROPTERA - Mayflies HEMIPTERA - Bugs HYMENOPTERA - Sawflies / Wasps / Ants / Bees LEPIDOPTERA - Butterflies LEPIDOPTERA - Moths MANTODEA - Mantids MEGALOPTERA - Dobsonflies / Alderflies / Fishflies NEUROPTERA - Lacewings / Antlions / Dobsonflies / Alderflies / Snakeflies ODONATA - Dragonflies / Damselfies ORTHOPTERA - Grasshoppers / Crickets / Katydids PHASMATODEA - Walking sticks / Leaf insects PLECOPTERA - Stoneflies, Salmonflies TRICHOPTERA - Caddisflies Photo GalleryLinks |
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