Male sperm or semen production is costly across diverse taxa. Consequently, depending on mate quality and the competitive intensity of rivals, males are predicted to adaptively invest their courtship and mating efforts to maximize their reproductive success, while prudently allocating their sperm. Presently, most studies on male plastic behavioral responses to rivals have mainly focused on polyandrous females. Recent studies provide evidence that male plastic behavioral responses are plentiful and varied, found in a wide range of taxa, and comprise behaviors that occur pre- or post-copulation. It is predicted that males altered aspects of their mating behavior when indirectly exposed to rival chemical cues, and directly exposed to the sex ratio or the presence, number, or density of rivals. Generally, males exhibit adaptively behavioral responses to rival cues to maximize their reproductive fitness. In contrast, we have limited information about male behavioral responses to rival cues in monandrous species. In the present study, we used the monandrous wolf spider, Pardosa astrigera, as a model system to test male plastic behavioral responses to rival chemical cues and different operational sex ratios. It is generally accepted that in wandering spiders, males depend on female silk-mediated chemical substances to search and locate mates. Besides encountering the silk of females of different periods, such as immature and mature virgin females, and mated females, males may also encounter male silk and a mix of female and male silk. Given that males gain mating opportunities via pre-copulatory mate choice, it is predicted that males may invest more courtship intensity in the silk of virgin females than those of males and/or a mix of female and male silk. When male P. astrigera individuals were exposed to the female silk previously occupied by themselves or other males, we compared the differences in male courtship latency, courtship duration, courtship intensity, and mating duration across mating treatments. Our results showed that male courtship intensity (foreleg raises per second and body shakes per second) was significantly reduced when they were exposed to female silk previously occupied by their own silk or by other males than female silk not previously occupied by males; however, there were no significant differences in male courtship latency, courtship duration, and mating duration. Although, when male P. astrigera individuals were directly exposed to different operational sex ratios, our results indicated that varied sex ratios showed a small effect on male courtship and mating behaviors. The present study concurs with our prediction, which shows that male P. astrigera possessed pre-copulatory adaptive responses to rival chemical cues, but showed limited plastic behavioral responses to operational sex ratios. To our knowledge, this is the first study to determine male plastic behavioral responses to conspecific rivals in monandrous spiders.