Larvicidal activity of diterpenes from Xylopia langsdorfiana St. Hilaire & Tulasne (Annonaceae) against Aedes aegypti linn. (diptera: culicidae).

Mosquitoes of the Aedes genus are responsible for transmitting many vector-borne viral diseases worldwide. Hundreds of thousands of people die annually from vector-borne diseases, including West Nile fever, dengue, tick-borne diseases, yellow fever, chikungunya, Rift Valley fever, and Zika. Billions of people are at the risk of infection on all continents, which is a cause of international concern. Therefore, new vector-control methods are essential for mitigating these illnesses. The bioactive hydrocarbons isolated from Xylopia langsdorfiana St. Hilaire & Tulasne are trachylobanes, a rare class of diterpenes found in the n-hexane fraction of the stem and leaf ethanolic extracts. These were tested against Ae. aegypti fourth-instar larvae over 48 h of exposure, with LC50 values ranging from 19.84 to 72.9 µg/mL, comparable to that of the positive control. The findings highlight the potential of Xylopia langsdorfiana St. Hilaire & Tulasne metabolites for controlling the main vectors of arthropod-borne viruses.

Morphology and distribution of antennal sensilla of Automeris liberia (Lepidoptera: Saturniidae).

The lepidopteran species Automeris liberia from the Saturniidae family is a polyphagous insect responsible for defoliating plants, such as the oil palm (Elaeis guineensis Jaquim). The antennae of insects play an important role in survival in various environments. Antennae are the main olfactory and sensory organs of insects and have different sensilla to detect chemical cues, movement, humidity and temperature. The olfactory structures present in the antennae are responsible for certain insect behavior, which is influenced by chemical communication. The morphology, distribution and location of the sensilla in the antennae of male and female A. liberia were investigated by scanning electron microscopy to understand the olfactory mechanisms relevant to insect-insect communication and insect-plant communication, among others. The results showed that the flagellum, scape and pedicel length and the number of antennomeres differed between the sexes and demonstrating the existence of sexual dimorphism in the antennae males (bipectinate) and females (filiform). According to the morphological data, seven types of sensilla were identified along the surface of the antennae, classified as trichodea, chaetica, basiconica, coeloconica, squamiformia, styloconica and Böhm's bristles. Among the sensilla chaetica, basiconica and Böhm's bristles, two subtypes based on length were identified in both sexes. The sensilla trichodea exhibited dimorphism since three subtypes were observed in males, while in females, only one subtype was observed, according to the length of the sensilla. Sensilla trichodea subtypes I and II were specific to males, while subtype III was observed in both sexes. These types of sensilla are involved in the recognition of pheromone molecules. Therefore, morphological study of the localization of the sensilla in the antennae will provide useful and relevant results for electrophysiological studies and behavioral tests. This information can help to understand the chemical communication of insects and helps in research directed strategies for pest control.