Mole Crickets (Scapteriscus spp.) are the most destructive pests in southern turf and pasture grasses. In response to extensive losses from mole crickets, Florida formed a task force to identify natural enemies in the native range of these pests. Two parasitic insects, Larra bicolor and Ormia depleta, and Steinernema scapterisci, an entomopathogenic nematode, were imported and released. Of the two insects, only Larra bicolor has spread to other states infested with mole crickets in the southeast. The present study documents the seasonal biology of Larra bicolor in the northern Gulf region, ornamental plants that can be used as nectar sources, and the impact of these nectar sources on longevity of the wasp and parasitism of mole crickets. Results of field and laboratory experiments showed that the ornamental Pentas lanceolata attracted wasps in the field and provided comparable or better longevity than Spermacoce verticillata which was the only known nectar source.

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The hemlock woolly adelgid (HWA) (Adelges tsugae [Annand]) (Hemiptera: Adelgidae) is a non-native lethal pest to eastern hemlock (Tsuga canadensis [L.] (Pinales: Pinaceae), and Carolina hemlock (Tsuga caroliniana [Engelmann]) (Pinales: Pinaceae). In the early 2000's, a robust biological control initiative using Laricobius spp. (Insecta: Coleoptera) was launched with the goal of decreasing HWA's impact to hemlock and the associated ecosystems on landscape level. Since then, two Laricobius agents, Laricobius nigrinus Fender (Coleoptera: Derodontidae) and Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae) have been evaluated, approved, and released. The production and subsequent release of these agents has largely occurred through mass rearing efforts by Virginia Tech. A descriptive analysis of these rearing and release data over the past 16 years at Virginia Tech revealed that the mass production of these agents has been consistently limited by: 1) excessively high rates of subterranean mortality and 2) early subterranean emergence. Very little is known about the subterranean life cycle of these species in the field in terms of survivorship and timing of emergence. Additionally, the thermal limits and rates of development are unknown for L. osakensis and were thus further investigated. In 2019, surveys within the urban environment in two counties in southwest Virginia were conducted to determine if these agents have dispersed from their original release location. Laricobius nigrinus was documented to have established outside of release sites in 100 and 75% of the surveyed grids containing HWA infested hemlocks. The establishments of these species in easily accessible locations allowed for the use of field-caught larvae, in addition to laboratory-produced larvae, for experiments. Experiments were conducted in 2019-2020 to determine the overall subterranean survivorship in relation to site condition, differences in survivorship between field-caught vs. laboratory-reared, and the seasonal timing of emergence. We found that the average field subterranean survivorship (17.1 ± 0.4%) was significantly less than the historical production of these agents in the laboratory (37.5 ± 13.6%). We found that as soil pH and organic matter depth increased, survivorship decreased. While the majority of emergence occurred as expected in the fall, a surprising amount of emergence also occurred in spring and summer. The rate of development and the minimum threshold temperature for each life stage were determined through constant temperature experiments, and were used in the construction of a phenological forecast model. Laricobius osakensis minimum threshold temperature (3.6°) from egg to adult was similar to that of other Laricobius spp., but completed development at higher a constant temperature (22°C). Our results suggest L. osakensis can handle the same colder climates as L. nigrinus, but may be better adapted for warmer locations than L. nigrinus. Laboratory rearing, establishment, subterranean survivorship, and thermal requirements of Laricobius spp. (Coleoptera: Derodontidae), biological control agents released for Adelges tsugae (Hemiptera: Adelgidae) / Doctor of Philosophy / Eastern and Carolina hemlocks are long lived, shade tolerant evergreen tree species that support a unique ecological assemblage of plants and animals. However, following the accidental introduction of a highly invasive aphid-like insect pest first found in the 1950s, known as the hemlock woolly adelgid (HWA), significant mortality of hemlocks in the eastern U.S. was eventually observed. In order to mitigate this pest's impact and to prevent the further collapse of this unique ecological system, a robust management program was initiated. Today, the primary management strategy to reduce HWA's deleterious effects is through the use of chemical and biological treatments. Biological treatments in the form of insect biological control agents, have focused on the use of two closely related beetle species in the genus Laricobius spp. These species were imported from their respective native ranges, biologically evaluated, and approved for release by federal and state agencies. Since then, the beetles have been mass-produced by multiple governmental and academic agencies and released on infested landscape on mostly public land. Key aspects of these species' biology in terms of their population patterns, development, distribution capabilities, and potential supplementary diet remains unknown. Therefore, investigations into these aforementioned aspects were conducted from 2018-2021 in both laboratory and field experiments. In order to supply beetle larvae for field experiments and to better understand how well these predatory beetles were establishing across the landscape, we investigated heavily urbanized areas for their presence. We found that L. nigrinus was established outside of release locations, in 100 and 75% of the surveyed grids containing HWA in southwest Virginia. Laricobius spp. spend a significant amount of their lives in a presumed dormant state beneath the soil during the summer months. Observations over the past 17 yrs. of rearing Laricobius spp. revealed relatively high rates of subterranean mortality and subterranean early emergence, both of which are substantial mortality factors. Through field experiments, the survivorship of these beneficial beetles was found to be 17.1 ± 0.4% and their seasonal emergence was not limited to fall.Comparing the average survivorship from our field study (17.1 ± 0.4% ) to that of the past 17 yrs. of laboratory production (37.5 ± 13.6%), there was significantly less survivorship. The developmental and phenological biology of one of the two Laricobius spp., L. osakensis was determined and found to be similar to that of other beetles. However, L. osakensis was able to complete development at 22°C, the highest developmental temperature recorded for any Laricobius spp. The similar phenological biology of these two predators will allow for precise larval sampling as a metric for establishment. Results and conclusions from these data have provided further knowledge to scientists, land managers, and public stakeholders regarding the benefits of Laricobius spp.

The mango (Mangifera indica L.) is an appealing subtropical fresh fruit with a pleasant flavor and taste, high nutritional value, beneficial medicinal properties and various processing options. However, as is the case with most subtropical fruit, it is a sensitive commodity, prone to losses postharvestly. The South African mango industry is highly dependent on a hot water and cold prochloraz dip treatment, to control postharvest anthracnose and soft brown rot on fruit destined for export. However, negatve public perceptions of synthetic fungicides and its use on fresh produce for disease control has been increasing in major export markets such as the European Union. This growing concern from a public point of view is forcing industry to consider more environmentally acceptable methods to maintain quality of mangoes during extended export periods. ‘Tommy Atkins’ and ‘Kent’ mangoes either uninoculated or artificially inoculated with Colletotrichum gloesporioiedes, Botryosphaeria parva or sterile agar, were used to evaluate softer, greener alternatives, in this study. Fruit were subjected to either a hot, Bacillus amyloliquefaciens (PPCB004) containing dip treatment for two minutes or a 24 hour 1-methylcyclopropene (1-MCP) gas treatment at 16 ºC or no treatment. Fruit were then stored at 10 ºC under either 5% O2 and 5% CO2 (CA-1) or 3% O2 and 8% CO2 (CA-2) controlled atmospheres (CA) for 18 days and allowed to ripen for five days at 25 ºC. Similarly, uninoculated or artificially inoculated fruit subjected to B. amyloliquefaciens, 1-MCP or a combination of the two treatments was stored at 10 ºC for 18 days under conventional storage. ‘Tommy Atkins’ fruit were packed into bags made from four different film types, untreated or after being subjected to a cold B. amyloliquefaciens dip treatment and stored for 23 days at 10 ºC. Overall, ‘Kent’ fruit were more susceptible to anthracnose and SBR after artificial inoculation. In vivo inoculated ‘Tommy Atkins’ fruit, storage under CA-1 gave the best control of soft brown rot whilst CA-2 storage gave the best control of anthracnose. For quality retention no definite conclusion could be made for both cultivars after CA storage or the combination of 1-MCP pre-treatment and CA storage. The combination of 1-MCP pre-treatment and B. amyloliquefaciens maintained the quality of ‘Kent’ mangoes under conventional storage the best. Anthracnose severity on both cultivars was reduced with 1-MCP treated fruit combined with the biocontrol pre-treatment. Modified atmosphere packaging in this study was found to be ineffective in maintaining quality of mangoes. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2011. / Microbiology and Plant Pathology / unrestricted

Neem cake is a product of the cold pressing from the neem kernels to obtain neem oil. Bio-active substances from neem cake extracted solutions were evaluated for their potential to control the root knot nematodes and other pests of plants. In this study different concentrations of the solution extracted from neem cake was tested against the second stage juveniles of the plant parasitic nematode Meloidogyne spp. and four phytopathogenic fungi: Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytopthora capsici. Toxicity of neem cake extractions is represented by the EC50 value for the second-stage juvenile (J2) of Meloidogyne spp. and the four phytopathogenic fungi via Probit analysis. A 5% dilution of the solvent extracting from neem cake already caused 100% larval mortality after 24 hours exposure. Undiluted neem cake extraction effectively inhibited the growth of the four phytopathogenic fungi. The EC50 value of neem cake on J2-larvae of Meloidogyne nematode and on the fungi Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytophthora capsici was 0.51, 0.74, 0.30, 0.51 and 4.33%, respectively. / Bánh dầu neem là sản phẩm của quá trình ép nhân hạt neem để lấy dầu. Các hoạt chất sinh học từ dịch chiết bánh dầu neem đã được đánh giá có tiềm năng lớn trong phòng trừ tuyến trùng nốt sưng và các loài dịch hại khác của nhiều loại cây trồng. Trong nghiên cứu này các nồng độ dịch chiết khác nhau của bánh dầu neem đã được thử nghiệm khả năng diệt tuyến trùng (ấu trùng tuổi 2 thuộc giống Meloidogyne spp.) và ức chế 4 loài nấm bệnh như: Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. và Phytopthora capsici. Độc tính của dịch chiết bánh dầu neem được biểu diễn bởi giá trị EC50 đối với ấu trùng tuổi 2 của tuyến trùng Meloidogyne spp. và các loài nấm bệnh thông qua phân tích Probit. Dịch chiết bánh dầu neem ở nồng độ 5% đã làm chết 100% cá thể IJ2 của Meloidogyne spp sau 24 giờ phơi nhiễm. Dịch nguyên chất bánh dầu neem ức chế cả 4 loài nấm bệnh. Giá trị EC50 của bánh dầu neem lên ấu trùng tuổi 2 của Meloidogyne spp và các loài nấm bệnh Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytophthora capsici tương ứng là 0.51, 0.74, 0.30, 0.51 và 4.33%.

Neem cake is a product of the cold pressing from the neem kernels to obtain neem oil. Bio-active substances from neem cake extracted solutions were evaluated for their potential to control the root knot nematodes and other pests of plants. In this study different concentrations of the solution extracted from neem cake was tested against the second stage juveniles of the plant parasitic nematode Meloidogyne spp. and four phytopathogenic fungi: Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytopthora capsici. Toxicity of neem cake extractions is represented by the EC50 value for the second-stage juvenile (J2) of Meloidogyne spp. and the four phytopathogenic fungi via Probit analysis. A 5% dilution of the solvent extracting from neem cake already caused 100% larval mortality after 24 hours exposure. Undiluted neem cake extraction effectively inhibited the growth of the four phytopathogenic fungi. The EC50 value of neem cake on J2-larvae of Meloidogyne nematode and on the fungi Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytophthora capsici was 0.51, 0.74, 0.30, 0.51 and 4.33%, respectively. / Bánh dầu neem là sản phẩm của quá trình ép nhân hạt neem để lấy dầu. Các hoạt chất sinh học từ dịch chiết bánh dầu neem đã được đánh giá có tiềm năng lớn trong phòng trừ tuyến trùng nốt sưng và các loài dịch hại khác của nhiều loại cây trồng. Trong nghiên cứu này các nồng độ dịch chiết khác nhau của bánh dầu neem đã được thử nghiệm khả năng diệt tuyến trùng (ấu trùng tuổi 2 thuộc giống Meloidogyne spp.) và ức chế 4 loài nấm bệnh như: Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. và Phytopthora capsici. Độc tính của dịch chiết bánh dầu neem được biểu diễn bởi giá trị EC50 đối với ấu trùng tuổi 2 của tuyến trùng Meloidogyne spp. và các loài nấm bệnh thông qua phân tích Probit. Dịch chiết bánh dầu neem ở nồng độ 5% đã làm chết 100% cá thể IJ2 của Meloidogyne spp sau 24 giờ phơi nhiễm. Dịch nguyên chất bánh dầu neem ức chế cả 4 loài nấm bệnh. Giá trị EC50 của bánh dầu neem lên ấu trùng tuổi 2 của Meloidogyne spp và các loài nấm bệnh Rhizoctonia solani, Sclerotium rolfsii, Collectotrichum spp. and Phytophthora capsici tương ứng là 0.51, 0.74, 0.30, 0.51 và 4.33%.

To investigate nematicidal activity against the root-lesion nematode, Pratylenchus coffeae, the methanolic extracts were obtained from 5 medicinal plants in Vietnam. Methanol extracts of the 5 samples were screened for nematicidal activity against Pratylenchus coffeae in vitro. Of the plant extracts tested, a 5 mg/ml concentration of Terminalia nigrovenulosa extract showed the highest level (95.0%) of nematicidal activity against Pratylenchus coffeae at 9 h after treatment. The remainder of the plant extracts was followed by Cinnamomum camphora (66.7%), Jasminum suptriplinerve (30.8%), Premna integrifolia (6.7%), and Treptocaulon juventas (5.8%). A 2.0 mg/ml concentration of T. nigrovenulosa resulted in 13.3, 42.5, 62.5 and 86.7% at 1, 3, 5 and 7 h after treatment, respectively against Pratylenchus coffeae. Concentration of 0.1, 0.5, 1.0 and 2.0 mg/ml of T. nigrovenulosa resulted in 26.7, 71.7, 78.3 and 86.7% effectiveness respectively, at 7 h after treatment. Also, at 3 days after exposure to T. nigrovenulosa, hatch was inhibited by 60.0, 45.8, 17.5 and 5.8% at 0.1, 0.5, 1.0 and 2.0 mg/ml, respectively. Hatch was inhibited by 65.0, 50.8, 21.7 and 6.7% at 0.1, 0.5, 1.0 and 2.0 mg/ml respectvely, at 6 days after exposure to T. nigrovenulosa. The mortality rate and hatch inhibition increased with increasing incubation time for crude extract of T. nigrovenulosa. / Trong nghiên cứu này, 5 cây thuốc (Cinnamomum camphora, Jasminum suptriplinerve, Premna integrifolia, Terminalia nigrovenulosa, Treptocaulon juventas) đã được sử dụng làm nguyên liệu chiết xuất bằng methanol để thử hoạt tính kháng tuyến trùng Pratylenchus coffeae. Kết quả cho thấy chiết xuất từ cây Terminalia nigrovenulosa biểu hiện hoạt tính kháng tuyến trùng cao nhất (95,0%) sau 9 giờ xử lý với nồng độ 5 mg/ml. Hoạt tính kháng tuyến trùng của các chất chiết xuất được biểu hiện theo thứ tự giảm dần lần lượt là C. camphora (66,7%), J. suptriplinerve (30,8%), P. integrifolia (6,7%) và T. juventas (5,8%). Với nồng độ 2 mg/ml của chất chiết xuất từ T. nigrovenulossa biểu hiện hoạt tính gây chết tuyến trùng Pratylenchuss coffeae là 13,3; 42,5; 62,5 và 86,7% sau 1, 3, 5 và 7 giờ xử lý theo thứ tự. Ở cùng thời điểm sau xử lý 7 giờ, các nồng độ 0,1; 0,5; 1,0 và 2,0 mg/ml chiết xuất của T. nigrovenulossa có hoạt tính gây chết tuyến trùng Pratylenchus coffeae lần lượt là 26,7; 71,7; 78,3 và 86,7%. Bên cạnh đó, chất chiết xuất của T. nigrovenulossa cũng cho thấy tỷ lệ ức chế trứng nở cao. Cụ thể là sau 3 ngày xử lý với chất chiết xuất của T. nigrovenulossa, tỷ lệ ức chế trứng không nở là 60,0; 45,8; 17,5 và 5,8% at 0,1; 0,5; 1,0 và 2,0 mg/ml theo thứ tự. Sau 6 ngày xử lý với chất chiết xuất của T. nigrovenulossa, tỷ lệ ức chế trứng nở là 65,0; 50,8; 21,7 và 6,7% tại nồng độ 0,1; 0,5; 1,0 và 2,0 mg/ml theo thứ tự. Tỷ lệ gây chết và tỷ lệ ức chế của chất chiết xuất phụ thuộc vào cả thời gian và nồng độ xử lý.