Effect of Nano-TiO2 Composite on the Fertilization and Fruit-Setting of Litchi

Titanium dioxide nanoparticles (nTiO₂) are widely used as fertilizers in agricultural production because they promote photosynthesis and strong adhesion. Low pollination and fertilization due to rainy weather during the litchi plant's flowering phase result in poor fruit quality and output. nTiO₂ would affect litchi during the flowering and fruiting stages. This study considers how nTiO₂ affects litchi's fruit quality and pollen viability during the flowering stage. The effects of nTiO₂ treatment on pollen vigor, yield, and fruit quality were investigated. nTiO₂ effectively improved the pollen germination rate and pollen tube length of litchi male flowers. The germination rate reached 22.31 ± 1.70%, and the pollen tube reached 237.66 μm in the 450 mg/L reagent-treated group. Spraying with 150 mg/L of nTiO₂ increased the germination rate of pollen by 2.67% and 3.67% for two types of male flowers (M1 and M2) of anthesis, respectively. After nTiO₂ spraying, the fruit set rates of 'Guiwei' and 'Nomici' were 46.68% and 30.33%, respectively, higher than those of the boric acid treatment group and the control group. The edibility rate, titration calculation, and vitamin C of nTiO₂ treatment were significantly higher than those of the control. The nTiO₂-treated litchi fruit was more vividly colored. Meanwhile, the adhesion of nTiO₂ to leaves was effectively optimized by using ATP and BCS to form nTiO₂ carriers and configuring nTiO₂ complex reagents. These results set the foundation for future applications of titanium dioxide nanoparticles as fertilizers for agriculture and guide their application to flowers and fruits.

Occurrence of the Sylvatic Yellow Fever Vector Mosquito Haemagogus leucocelaenus (Diptera: Culicidae) in an Atlantic Forest Fragment of the Touristic State of Rio de Janeiro, Brazil

The yellow fever virus is estimated to cause 30,000 deaths each year worldwide, with the majority of cases and deaths occurring in Africa. The virus is also endemic to Central and South America, including northern and western Brazil. The sylvatic cycle of the virus is related to wild and rural areas, with nonhuman primates as the primary host and wild mosquitoes, specifically from the genera Haemagogus, as vectors. The diversity of the mosquito community plays a significant role in the increase of pathogen transmission to humans. In the present study, we detected fluctuation in populations of vector mosquitoes using ovitraps for Culicidae egg collection. The study area is a forest fragment of the Atlantic Forest, one of the most threatened biomes in Brazil. This biome has been suffering significant deforestation due to anthropic activity. Worryingly, the proximity of human populations to forest environments increases the risk of spreading disease from forest fragments to urban areas. Our findings showed that the highest egg abundance occurred in December 2019, with a significant difference (p = 0.005) between rainy and dry seasons. Most eggs were collected during the rainy period. Subsequent quantification of specimens from epidemiologically relevant species hatched from field-collected eggs resulted in 1,131 (86%) Haemagogus leucocelaenus (Dyar & Shannon, 1924), 111 (8%) Aedes terrens (Walker, 1856), 47 (4%) Aedes albopictus (Skuse, 1894), and 21 (2%) Haemagogus janthinomys (Dyar, 1921). Finally, we assessed the behavior of different vector species performing oviposition on the same breeding site. The highest correlation coefficient was observed between Ae. albopictus and Ae. terrens (rho = 0.52) concerning other Culicidae species. Therefore, we believe that Culicidae population surveillance is crucial for disease monitoring since the increase in specimens of a number of vector species influences the emergence of yellow fever cases in nonhuman primates and human populations.