Environmental and Socio-Economic Impacts of Kariba Weed Infestation of Lakes Kyoga and Kwania, Uganda

The objective of this study was to quantify the coverage of Kariba weed (Salvinia molesta) on lakes Kyoga and Kwania and document the environmental and socio-economic impacts associated with its infestation. Data on weed infestation status was collected in 2017 and compared with pre-infestation period of 2013. Weed infestations were approximately 15,643 and 13,688 ha on lakes Kyoga and Kwania respectively. The infestation impaired fishing activities, water quality, water abstraction and water transport. They also led to 20.4, 60.1, 7.7, 17.6 and 5.7 kg reduction in catches per day for Tilapia, Mukene, Catfish, Nile perch and Mudfish respectively. The infestations were also associated with a general increase in the prices of the fish. Individual fishermen registered losses in fish revenue. Household spent approximately UGX 108,523 annually as treatment costs for diseases associated with weed infestation. While 32% of the respondents tried to manually control the waterweed at approximately UGX 83,988/year, the mobile nature of the weed rendered these efforts unsuccessful. A strategy to sustainably control the waterweed using specific bio-control agents (Cyrtobagous salviniae) is recommended.

Making the Shift from Research to Commercial Orchards: A Case Study in Aphid–Peach Tree Interactions as Affected by Nitrogen and Water Supplies

Peach orchards are intensively sprayed crops, and alternative methods must be found to replace pesticides. We intend here to evaluate if limiting water and nitrogen (N) supply could be effective in controlling aphid infestation in commercial orchards. N and water supply were therefore either unrestricted or restricted by 30% only for water, or for both water and N, in 2018 and 2019 on trees of two contrasting varieties. Natural infestations (green peach aphid, mealy plum aphid, leaf curl aphid) were monitored regularly at tree and shoot level. Infested and control shoots were compared for their development during the infestation period, their apex concentrations of total N, amino acids, non-structural carbohydrates, and polyphenols at infestation peak. At tree level, limiting both water and N supplies decreased the proportion of infested shoots by 30%, and the number of trees hosting the most harmful specie by 20 to 50%. Limiting only N supplies had almost no effect on infestation severity. At shoot level, the apex N concentration of infested shoots was stable (around 3.2% dry weight) and was found to be independent of treatment, variety, and year. The remaining biochemical variables were not affected by infestation status but by variety and year. Shoot development was only slightly affected by treatment. Aphids colonized the most vigorous shoots, being those with longer apical ramifications in 2018 and higher growth rates in 2019, in comparison with the controls. The differences were, respectively, 40 and 55%. It was concluded that a double restriction in water and N could limit, but not control, aphid infestations in commercial orchards.

Optimizing the location of watercraft inspection stations to slow the spread of aquatic invasive species

The accidental spread of aquatic invasive species (AIS) by recreational boaters is a major concern of state and county environmental planners in the USA. While programs for watercraft inspection to educate boaters and slow AIS spread are common practice, large numbers of boats and waterbodies, together with limited budgets, make program design difficult. To facilitate program design, we developed an integer programming model for allocation of scarce inspection resources among lakes. Our model uses species-specific infestation status of lakes and estimates of boat movement between lakes. The objective is to select lakes for inspection stations to maximize the number of risky boats inspected, where risky boats are ones that move from infested to uninfested lakes. We apply our model in Stearns County in central Minnesota, USA, to prioritize lakes for inspection stations and evaluate alternative management objectives. With an objective of protecting uninfested lakes within and outside Stearns County, the optimal policy is to locate stations at infested lakes having the most boats departing for uninfested lakes inside and outside the county. With an objective of protecting only Stearns County lakes, the optimal policy is to locate stations at both infested and uninfested lakes having the riskiest boats arriving from within and outside the county and departing to in-county lakes. The tradeoff between these objectives is significant.

Status of Weedy Rice (Oryza sativa L.) Infestation and Management Practices in Southern Brazil

Weedy rice (WR) (Oryza sativa L.) is the most troublesome weed infesting rice paddies in Brazil. Several changes have occurred in this region regarding crop management, especially WR control based on the Clearfield™ (CL) Rice Production System launched in 2003. This survey’s objective was to evaluate the WR infestation status by assessing the producers’ perception and the management practices used in southern Brazil after eighteen years of CL use in Brazil. Rice consultants and extension agents distributed a questionnaire with 213 producers in the Rio Grande do Sul (RS) and Santa Catarina (SC) state in the 2018/19 growing season. In RS, most farms are larger than 150 ha, farmers use minimal or conventional tillage, permanent flooding, adopted the CL system for more than two years, use clomazone PRE tank-mixed with glyphosate at the rice spiking stage, and use crop rotation with soybean [Glycine max (L.) Merr.] or pasture. In SC, rice farms are small, averaging from 20 to 30 ha, farmers predominantly plant pre-germinated rice and do not rotate rice with other crops and roguing is practiced. Comparing both states, the CL System is used in 99.5, and 69.3% of the total surveyed rice area in RS and SC, respectively. Imidazolinone-resistant WR is present in 68.4 and 26.6% of rice farms in RS and SC, respectively. Rice cultivation in Brazil is currently coexisting with WR with minimal integration of control methods. However, integrated practices can control this weed and are fundamental to the sustainability of systems based on herbicide-resistant rice cultivars.

MULTIPLEX POLYMERASE CHAIN REACTION ASSAY FOR THE DETECTION OF FIVE COMMON ENDOPARASITE INFESTATIONS IN LABORATORY RODENTS

Rodent pinworms, Spironucleus muris and Tritrichomonas muris are the endoparasites that should be monitored and excluded from laboratory animal colonies. Nevertheless, traditional diagnostic methods may not efficiently detect and accurately demonstrate the endoparasite infestation status. In this study, we developed a multiplex PCR assay targeting the rRNA genes to simultaneously detect and differentiate five endoparasites, including Syphacia obvelata, Syphacia muris, Aspiculuris tetraptera, Spironucleus muris, and T. muris, as well as a housekeeping gene in feces. The multiplex PCR could identify an equivalent infection of pinworm, Spironucleus muris and T. muris, with a detection limit of as few as 10 copies. Furthermore, dual infections with up to 100-fold differences and triple infections with 10-fold differences in parasite loads can also be detected. In comparison of traditional methods with the multiplex PCR assay, 76 rodents from 11 research colonies and 3 pet shops and additional 27 fecal samples from laboratory rodents were screened for the infestation status of the five endoparasites. The multiplex PCR had higher sensitivity (97.2–100%) and accuracy (99–100%) than those of the traditional antemortem (sensitivity: 83–100%; accuracy: 94–100%) and postmortem methods (sensitivity: 75–100%; accuracy: 92.1–100%). In addition, an early stage of S. obvelata contamination in a SPF laboratory animal colony was also successfully detected by this multiplex PCR assay. This Pinworm/Spironucleus/Tritrichomonas/Actin Multiplex PCR assay should be a powerful tool to screen endoparasite infestations in laboratory colonies without animal sacrifice.

NOVEL PCR ASSAYS FOR THREE FUR MITES IN NATURALLY INFECTED MICE WITHOUT ANIMAL SACRIFICE

Rodent fur mite infestation is a persistent and intractable problem in laboratory rodent colonies, due to insensitive diagnostics, unrepresentative samples for testing and improper sentinel system. Myocoptes musculinus (COP), Myobia musculi (MOB) and Radfordia affinis (RDA) have been reported in laboratory mouse colonies. To improve the sensitivity and efficiency of fur mite detection, COP-specific PCR and MOB/RDA-specific PCR assays were developed to detect and differentiate these fur mites, with the existence of a rodent housekeeping gene. The COP-specific PCR and the MOB/RDA-specific PCR could specifically detect COP and MOB/RDA at as low as 10 copies, respectively. In comparison of the specific PCRs with traditional methods (pluck test, tape test and pelt exam) for fur mite diagnosis, 31 rodents and 17 cage environment samples were evaluated. In screening for the infestation status of various fur mites on individual animals, the specific PCR assays showed distinctly higher sensitivity and accuracy (100% and 100%) than those of the traditional methods (sensitivity: 25–80%, accuracy: 83.9–96.8%). Interestingly, by using cage wipe environmental samples, the specific PCR assays exhibited 100% sensitivity and accuracy in the fur mite detection and differentiation. The COP-specific and MOB/RDA-specific PCR assays developed in this study could be reliable alternatives for routine pathogen monitoring of laboratory mice and environments of animal facilities without animal sacrifice. [Chou C-L, Cheng Y-C, Wang MH, Wan CH, Novel PCR assays for three fur mites in naturally infected mice without animal sacrifice, Taiwan Vet J XX(X):XX–XX, 2020.

OILSEED MOISTURE MONITORING DEVICES

Storage of seeds is the final and longest operation in the complex technological process of their production. Violation of storage conditions leads to a decrease in not only sowing, but also commodity and feed qualities of oilseeds. The main characteristics that need to be monitored during seed storage are: humidity, temperature, pest infestation status, and freshness index. Controlling the moisture content of seeds is of great importance when storing them and is standardized by GOST. The level of humidity when storing seeds up to a year should not exceed: for sunflower seeds and rapeseed - 7%, soy-12%. The article presents an analysis and comparative characteristics of modern methods and devices for measuring the moisture content of oilseeds.

The Fate of Ornamental White Fringetree Through the Invasion Wave of Emerald Ash Borer and Implications for Novel Host Use by This Beetle

Emerald ash borer (EAB, Agrilus planipennis Fairmaire [Coleoptera: Buprestidae]) is a wood boring beetle that is an invasive pest of ash trees (Fraxinus spp.) in North America. In 2014, it was reported that EAB had infested white fringetree (Chionanthus virginicus L. [Lamiales: Oleaceae]) in Ohio and was since found to have infested this species across its invasive range. In 2018, we reexamined 166 white fringetrees in Illinois, Indiana, Ohio, and Pennsylvania that had been previously examined for EAB attack in 2015 to determine their fate. We assessed tree health and EAB infestation in each tree, assigned an infestation status of newly, continuously, not reinfested, or never infested, and compared the trees’ current status to their 2015 status. This assessment was done to determine whether their health and infestation status had changed through the EAB invasion wave. We found that attack rates declined: 26% of trees were infested in 2015 whereas only 13% were in 2018, likely coinciding with declining beetle populations in the area. Overall tree health improved for trees that were not reinfested by EAB after a record of attack in 2015, suggesting that they can survive and recover from EAB attack. Conversely, health declined for newly and continuously infested trees, indicating that they became stressed from EAB attack. Although the majority of the trees survived the invasion wave, several were removed from various sites due to EAB attack suggesting that white fringetree varies in its resistance and tolerance to attack. As beetle populations continue to expand geographically, infestation rates will likely increase and health of white fringetrees will decrease with the EAB attack wave, especially as EAB reaches denser populations of fringetrees.

Behavioral Genetics of the Interactions between Apis mellifera and Varroa destructor

The western honeybee Apis mellifera exhibits a diverse set of adaptations in response to infestations by its most virulent disease-causing agent, the ectoparasitic mite Varroa destructor. In this study, we investigated the effect of honeybee pupae genotype on the expression of four host and parasite traits that are associated with the reproductive phase of the mite in the brood of its host. We first phenotyped cells containing bee pupae to assess their infestation status, their infestation level, the reproductive status of the mites, and the recapping of cells by adult workers. We then genotyped individual pupae with five microsatellites markers to compare these phenotypes across full sister groups. We found that the four phenotypes varied significantly in time but did not across the subfamilies within the colonies. These findings show that V. destructor mites do not differentially infest or reproduce on some particular honeybee patrilines, and that workers do not target preferentially specific pupae genotypes when performing recapping. These findings bring new insights that can help designing sustainable mite control strategies through breeding and provide new insights into the interactions between A. mellifera and V. destructor.