Thielaviopsis paradoxa and cultivable mycobiota associated with carapace of Rhynchophorus palmarum L. (Coleoptera: Curculionidae) in the state of Alagoas, Brazil.

Rhynchophorus palmarum (Coleoptera: Curculionidae) is a significant agricultural pest in palm plantations across tropical America, playing a critical role as a vector of the fungus Thielaviopsis paradoxa, which is the causative agent of stem bleeding disease in coconut palms. This disease has raised concerns due to its rapid spread and subsequent reduction in coconut production in northeastern Brazil. Additionally, this insect can establish mutualistic interactions with various fungi, including saprophytic, phytopathogenic, and entomopathogenic fungi, underscoring the importance of identifying its external mycobiota. The aim of this study was to assess the presence of T. paradoxa in the digestive tract and identify the cultivable mycobiota associated with the carapace of R. palmarum. To achieve this, a mycological study was conducted by culturing the external surface and digestive tract of field-caught adult insects (10 males and 10 females) on potato dextrose agar (PDA) in Maceió, Alagoas, Brazil. Fungal identification was performed by correlating microscopic features with the macroscopic characteristics of the obtained colonies. The results showed that T. paradoxa was detected in 15.0% of carapace isolates but was not found in the insects' intestinal tract. Additionally, nine fungal genera frequently associated with saprophytic or phytopathogenic behaviors were identified on the carapace. Eight of these genera belong to the Ascomycota phylum, while one is classified in the Basidiomycota phylum. The ubiquitous presence of Paecilomyces spp. and the occurrence of Trichosporon spp. in 95% of the assessed insects stand out. Furthermore, other potentially phytopathogenic fungi such as Penicillium spp., Fusarium spp., and Aspergillus spp., as well as fungi with entomopathogenic potential like Paecilomyces spp., Trichoderma spp., Metarhizium spp., and Beauveria bassiana, were detected. These findings enhance the understanding of the complex interactions between R. palmarum and its fungal hosts, providing insights for integrated pest management strategies.

Lipophorin interaction with the midgut of Rhodnius prolixus: characterization and changes in binding capacity.

Several classes of lipids are transported in insect hemolymph by lipophorin, a major hemolymphatic lipoprotein. The binding of lipophorin to the midgut of the hematophagous insect Rhodnius prolixus was characterized in a midgut membrane preparation, using purified lipophorin radiolabelled in protein moiety ((125)I-HDLp). Lipophorin specific binding to membranes achieved equilibrium after 30-40 min, was sensitive to pH, and was maximal at pH 7.0. In the presence of increasing concentrations of membrane protein, corresponding increases in lipophorin binding were observed. The specific binding of lipophorin to the membrane preparation was a saturable process, with K(d)=0.9+/-0.06 x 10(-7) M and a maximal binding capacity of 70+/-11 ng lipophorin/microg of membrane protein. Lipophorin binding did not depend on calcium, but it was affected by ionic strength and was inhibited in the presence of increasing salt concentrations. Suramin interfered with lipophorin binding to the midgut receptor, and it was abolished in the presence of 2 mM suramin, but at concentrations between 0.05 and 0.2 mM it was slightly increased. Condroitin 4-sulfate also affected lipophorin binding, which was reduced to 56% of control. Pre-incubation of the midgut membrane preparation with trypsin or at high temperature inhibited binding. Midgut capacity to bind lipophorin varied at different days after blood meal. It was highest at second day after feeding, and then gradually decreased.

Characterization of ectophosphatase activities in trypanosomatid parasites of plants.

ABSTRACT In the present work ectophosphatase activities of three trypanosomatid parasites of plants were characterized using intact cells. Phytomonas françai, Phytomonas mcgheei, and Herpetomonas sp. hydrolyzed p-nitro-phenylphosphate at a rate of 5.40, 7.28, and 25.58 nmol Pi/mg of protein per min, respectively. Experiments using classical inhibitors of acid phosphatases such as sodium orthovanadate (NaVO(3)) and sodium fluoride (NaF) showed a decrease in phosphatase activities. Lithium fluoride (LiF) and aluminum chloride (AlCl(3)) were also used. Although AlCl3 had no effect, LiF was able to promote a decrease in the phosphatase activities. Interestingly, the inhibition caused by LiF was enhanced by the addition of AlCl3 during the reaction, probably due to the formation of fluoroaluminate complexes. This effect was confirmed by cytochemical analysis. In this assay, electron-dense cerium phosphate deposits were visualized on the external surface of the three parasites.