The external morphology of sensilla on the antennae of males and females of Phyllophaga ravida Blanchard is described using scanning electron microscopy. Sexual dimorphism in body and antennal dimensions and in antennal receptor types was found. The female's body is slightly larger than the male's, although male antennal lamellae are longer than in females. Sixteen types of sensilla were identified on the proximal and distal surfaces of lamellae from both sexes, most of them in males: three types of placodea sensilla, four types of auricilica sensilla, five types of basiconica sensilla, and four types of coeloconica sensilla. Also, two types of mechanoreceptor sensilla were present on the lamellae periphery. Furthermore, males had larger placodea, auricilica and some types of basiconica sensilla.

Insecticides are pesticides used to control insects in agriculture, ornamental gardens, homes, and veterinary medicine. Although the toxic effects on the environment and the health of living beings are not fully understood, these pesticides have become the first options for crop protection in agriculture. After herbicides, insecticides are the most extensively used pesticides in agriculture, with large quantities consumed on every continent, primarily in America. Chlorpyrifos, carbaryl, and imidacloprid are among the top ten most used insecticides. Amidst organophosphates, chlorpyrifos has been reported to be used in over fifty food crops. Carbaryl is a carbamate employed as an insecticide, fungicide, herbicide, and nematicide. Similarly, neonicotinoids are the most used insecticide on a global scale. Neonicotinoids include imidacloprid, the second most frequently used pesticide, surpassed only by glyphosate. It is used because it is less toxic to humans. However, insects appear to be less resistant to its compounds. Evidence suggests that these insecticides persist in soils for a long time and have neurotoxic effects in animal species not intended to receive its consequences. Thus, this chapter’s aim is to describe these three pesticides effects and contrast them with the most recent findings regarding their neurotoxic effects in various animal species.

In the study of the chemical communication of adults of the Melolonthidae family, bacteria have been observed in the epithelium of the genital chamber; possibly, bacteria are involved in the production of sex attractants in their hosts. Therefore, it is important to identify the volatile organic compounds from bacteria (VOCsB) released by these microorganisms and study the biological activity stimulated by VOBCs in adults of Melolonthidae. In this study, bacteria were isolated from the genital chamber of Cyclocephala lunulata and Cyclocephala barrerai, from which VOCsB were extracted using static headspace solid-phase microextraction (SHS-SPME) and dynamic headspace Super Q solid-phase extraction (DHS-SPE) and analyzed using gas chromatography-mass spectrometry. The effect of VOCsB on the hosts and conspecifics was evaluated utilizing an olfactometer and electroantennography (EAG). Two species of Enterobacteria were isolated from the genital chamber of each female species, and VOCsB derived from sulfur-containing compounds, alcohols, esters, and fatty acids were identified. An attraction response was observed in olfactometry studies, and antennal responses to VOCsB were confirmed in EAG bioassays. With these results, new perspectives on the relationship between these beetles and their bacteria emerge, in addition to establishing a basis for management programs in the future.

Females of Phyllophaga obsoleta Blanchard (Coleoptera: Melolonthidae) display a typical “calling” behavior by protruding the abdominal tip and exposing their genital chamber. This is the moment when the sex pheromone is released into the environment. The genital chamber and accessory glands have a specialized epithelia involved in production of the chemicals. In other species of the group (e.g., Costelytra zealandica White), bacteria have been confirmed to be involved. We identified the microorganisms in the genital chamber of females of P. obsoleta. Two types of bacterial colonies were isolated from the inside of the genital chamber and identified using the 16S rRNA gene sequence. The sequence of one of the bacterial colonies was a 97% match with the Klebsiella oxytoca strain HP1 sequence, while the sequence of the other bacterial colony was a 98% match with the Klebsiella michiganensis strain VITSW4 sequence. Microbiological and biochemical tests were used for taxonomic identification. Both ba...

Placodea (PLAS), auricilica (AUS), and basiconica (BAS) sensilla types were identified in both surfaces of lamellae of Macrodactylus mexicanus (Burmeister) and Macrodactylus nigripes (Bates), two species of chafer beetles with economic importance in Mexico. Fourteen subtypes of sensilla were identified on the inner and external surfaces of lamellae from both sexes of M. mexicanus and M. nigripes: four PLAS, three AUS, and seven BAS. Distribution of PLAS, BAS, and AUS in the inner surface of the lamellae of both sex of M. mexicanus and M. nigripes was similar in middle and proximal lamellae. PLAS are distributed in the peripheral edges, while BAS and AUS were distributed in the center of the lamellae. The purpose of this study was to compare the sensilla distribution in the antennae of the beetles as a first step to better understand the dynamics of sexual chemical communication in Macrodactylus species.