Efficacy of attenuated bacteria vaccine against streptococcal infection in larvae tilapia (Oreochromis niloticus)

One of the common diseases found in tilapia is a streptococcal disease caused by the Streptococcus agalactiae bacteria. Treatment of this disease is generally done by using antibiotics. The use of antibiotics in controlling disease in fish can create resistant bacterial strains with certain doses. The use of vaccines is one of the alternative control methods in fish defence against infections. The purpose of this study was to analyze the efficacy of vaccination on seeds through immersion using attenuated active bacteria to increase immunity at the beginning of the spread of streptococcosis disease. The vaccine used was obtained from attenuated Streptococcus agalactiae bacteria through repeated passage ten times. Vaccination was carried out through oral vaccine. Challenge tests were carried out on days 7, 14, and 21 days after vaccination on tilapia larvae by immersion. The result indicated that vaccination using attenuated bacteria could increase lysozyme activity at each observation time compared to control. The mortality of post-challenged larvae on days 7, 14 and 21 post-vaccination was lower than that of unvaccinated seed. The percentage of RPS values up to the 14th day of observation has increased and tends to decrease on the 21st day.

A Review of Alternative Management Tactics Employed for the Control of Various Cockroach Species (Order: Blattodea) in the USA

Effective control of domestic and peridomestic cockroaches requires integrated approaches that emphasize concurrent use of chemicals with alternative control tactics. An integrated pest management (IPM) approach is particularly justified in environments where satisfactory cockroach control cannot be achieved due to multiple factors including development of insecticide aversion and resistance in some cockroach species, and poor sanitation or structural issues that foster infestations. While a flurry of research effort has been devoted to study alternative tactics for cockroach control, only a few of them have been evaluated in the context of IPM programs. This review focuses on examining studies on alternative tactics that are proven efficacious, economical, and logistically feasible for their inclusion in IPM programs for important domestic and peridomestic cockroaches in the USA. Management programs that educate the public on cockroach biology, behavior, and the importance of sanitation; use of traps to monitor infestation levels; apply targeted low impact insecticides such as baits, have demonstrated a greater success for effective and sustainable control of cockroaches when compared to an insecticide-only approach. Incorporation of other alternative control methods to IPM programs will require more applied research that validates their use in real-world scenarios and demonstrates their cost-effectiveness.

Crop Diversification to Control Powdery Mildew in Pea

Pea is a temperate grain legume cultivated worldwide that can be severely constrained by powdery mildew infection. Control by fungicides and the use of resistant cultivars is possible, but there is a growing interest in alternative control methods such as crop diversification, particularly in low input agriculture. The aim of this work was to assess the potential of intercropping pea with other crops and of pea cultivar mixtures for powdery mildew management on pea crop. Results show a reduction of powdery mildew on pea when intercropped by replacement at a 50:50 ratio with barley or with faba bean, but not when intercropped with wheat. A barrier effect seems to explain a major part of this decrease, especially in the pea/barley intercrop. This hypothesis was further supported by inoculated seedlings under controlled conditions, where powdery mildew infection on pea decreased with the distance to the inoculation point, this decrease being larger in the intercrop with barley than in the intercrop with wheat and in the pea monocrop. Powdery mildew was also reduced in the mixture of resistant and susceptible cultivars, with infection decreasing with the increasing proportions of the resistant one. Overall, this work shows that crop diversification may be a good strategy to reduce powdery mildew in pea.

Alternatives to Synthetic Insecticides in the Control of the Colorado Potato Beetle (Leptinotarsa decemlineata Say) and Their Environmental Benefits

In this study, we review the wide range of alternative control methods used to this day to control the Colorado potato beetle (Leptinotarsa decemlineata Say), the biggest potato pest globally. We further categorize and highlight the advantages and disadvantages of each method by comparing them to conventional insecticides. In a second step, we point out the current knowledge about positive and negative impacts of using alternative control methods. By this, we illustrate how alternative control methods, farmers’ activities, and environmental factors (e.g., biodiversity and ecosystem health) are heavily linked in a cycle with self-reinforcing effects. In detail, the higher the acceptance of farmers to use alternative control methods, the healthier the ecosystem including the pest’s enemy biodiversity. The following decrease in pest abundance possibly increases the yield, profit, and acceptance of farmers to use less conventional and more alternative methods. Overall, we try to balance the positive and negative sides of alternative control methods and combine them with current knowledge about environmental effects. In our view, this is a fundamental task for the future, especially in times of high species loss and increasing demand for environmentally friendly agriculture and environmentally friendly products.

Variation in the susceptibility of urban Aedes mosquitoes infected with a densovirus

Urban Aedes mosquitoes are vectors of many viruses affecting human health such as dengue, chikungunya and Zika viruses. Insecticide resistance and environmental toxicity risks hamper the effectiveness of chemical control against these mosquito vectors. Alternative control methods, such as the use of mosquito-specific entomopathogenic viruses should be explored. Numerous studies have focused on evaluating the potential of different densoviruses species as biological control agents. However, knowledge on the extent of inter- and intra-specific variations in the susceptibility of Aedes mosquitoes to infection by different densoviruses remains insufficient. In this study, we compared infection and mortality rates induced by the Aedes albopictus densovirus 2 in different strains of Aedes albopictus and Aedes aegypti mosquitoes. The two Aedes species were different in terms of susceptibility to viral infection. Under laboratory conditions, Aedes albopictus densovirus 2 appeared more virulent for the different strains of Aedes aegypti tested than for those of Aedes albopictus. In addition, we also found significant intra-specific variation in infection and mortality rates. Thus, although even if Aedes albopictus densoviruses could be powerful biocontrol agents used in the management of urban Aedes populations, our results also call into question the use of single viral isolate as biocontrol agents.

Mosquito Mycobiota: An Overview of Non-Entomopathogenic Fungal Interactions

The growing expansion of mosquito vectors leads to the emergence of vector-borne diseases in new geographic areas and causes major public health concerns. In the absence of effective preventive treatments against most pathogens transmitted, vector control remains one of the most suitable strategies to prevent mosquito-borne diseases. Insecticide overuse raises mosquito resistance and deleterious impacts on the environment and non-target species. Growing knowledge of mosquito biology has allowed the development of alternative control methods. Following the concept of holobiont, mosquito-microbiota interactions play an important role in mosquito biology. Associated microbiota is known to influence many aspects of mosquito biology such as development, survival, immunity or even vector competence. Mosquito-associated microbiota is composed of bacteria, fungi, protists, viruses and nematodes. While an increasing number of studies have focused on bacteria, other microbial partners like fungi have been largely neglected despite their huge diversity. A better knowledge of mosquito-mycobiota interactions offers new opportunities to develop innovative mosquito control strategies. Here, we review the recent advances concerning the impact of mosquito-associated fungi, and particularly nonpathogenic fungi, on life-history traits (development, survival, reproduction), vector competence and behavior of mosquitoes by focusing on Culex, Aedes and Anopheles species.

Nigeria’s Lagos will struggle to curb COVID-19 spread

Subject Lagos' eased lockdown. Significance Lockdown restrictions in densely populated Lagos State, the country’s economic hub, as well as Ogun State and Abuja, the initial epicentres of Nigeria’s COVID-19 outbreak, were eased from May 4. With the partial reopening of businesses, Lagos' authorities are trying to enforce containment measures, including a night-time curfew, social distancing requirements and compulsory wearing of face masks. However, these have proven difficult to implement. Impacts Abuja is unlikely to intervene in future Lagos restrictions, given Buhari's partial lockdown strategy has been viewed as ineffective. The authorities may be forced to try alternative control methods, such as staggered business operating days or select 24-hour curfews. Schools may not be able to re-open or businesses run at full capacity until towards the end of the third quarter of the year (at least). The governor’s standing has been boosted by his crisis response despite controversy over a ban on commercial motorcycles on Lagos' roads.

In Vitro Inhibiting Effects of Three Fungal Species on Eggs of Donkey Gastrointestinal Strongyles

Recently, donkeys have gained popularity mainly due to the use of donkey milk by the cosmetic industry and for human consumption. Gastrointestinal strongyles (GIS) are considered a potential cause of disease and reduced production in infected donkeys. European laws limit the use of anthelmintic drugs for the control of GIS in dairy donkey farms, thus the need to develop alternative control methods. This study aimed to test the in vitro inhibiting effects of three chitin degrading fungi (Scopulariopsis brevicaulis, Metarhizium anisopliae, and Beauveria bassiana) on the hatch and viability of donkey GIS eggs by using the egg hatch test, and to compare their activity to that of Pochonia chlamydosporia. About 150 eggs were added to 0.5 mL of sterile saline solution containing about 1.4 × 108 spores of each fungal species or with 0.5 mL of sterile saline solution only (untreated controls). After incubation, the percentage of egg hatch reduction was calculated, and data were statistically analyzed. All fungi were able to significantly reduce (p < 0.05) the hatch of GIS eggs compared to the untreated controls. Further studies that aim to investigate the efficiency of these fungi in reducing donkey GIS eggs in contaminated environments are encouraged.