Pheromones are critical cues for attracting mating partners for successful reproduction. Sexually mature Caenorhabditis remanei virgin females and self‐sperm‐depleted Caenorhabditis elegans hermaphrodites produce volatile sex pheromones to attract adult males of both species from afar. The chemoresponsive receptor in males has remained unknown. Here, we show that the male chemotactic behavior requires amphid sensory neurons (AWA neurons) and the G‐protein‐coupled receptor SRD‐1. SRD‐1 expression in AWA neurons is sexually dimorphic, with the levels being high in males but undetectable in hermaphrodites. Notably, srd‐1 mutant males lack the chemotactic response and pheromone‐induced excitation of AWA neurons, both of which can be restored in males and hermaphrodites by AWA‐specific srd‐1 expression, and ectopic expression of srd‐1 in AWB neurons in srd‐1 mutants results in a repulsive behavioral response in both sexes. Furthermore, we show that the C‐terminal region of SRD‐1 confers species‐specific differences in the ability to perceive sex pheromones between C. elegans and C. remanei. These findings offer an excellent model for dissecting how a single G‐protein‐coupled receptor expressed in a dimorphic neural system contributes to sex‐specific behaviors in animals.
The pink pineapple mealybug, Dysmicoccus brevipes (Cockerell) (Hemiptera: Pseudococcidae), is a widespread plant-sucking insect of considerable concern because it transmits the pineapple mealybug wilt-associated virus. The purpose of this study was to use molecular methods to clarify the relationship among pink pineapple mealybugs from China, Philippines, Thailand and Hawaii, in an effort to determine the geographic origin of the introduction to China. Pink pineapple mealybug samples were collected from 10 counties of 5 provinces in China, and samples from Hawaii were obtained. Parts of the mitochondrial genes for cytochrome oxidase I (COI) were sequenced for each sample, homologous DNA sequences of samples from the Philippines and Thailand were downloaded from GenBank. Three haplotypes were found in China, 1 from populations of mainland China, and 2 from Hainan island. Phylogenetic analyses suggested that most pink pineapple mealybugs on mainland China probably were closely related to populations in the Republic of the Philippines. However mealybugs from Wanning, Hainan, China, represented a different lineage that clearly diverged from other populations, and which may be of a cryptic lineage or species in the pink pineapple mealybug complex. The probable geographic origin of pink pineapple mealybugs in China is discussed.
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