Laboratory-Based Mate Choices of Two Eccritotarsus Species (Hemiptera: Miridae) Used as Biological Control Agents of Water Hyacinth, Pontederia (Eichhornia) crassipes (Pontederiaceae), in South Africa

Abstract

Abstract Many biological control agents have been released to manage the water hyacinth, Pontederia (Eichhornia) crassipes (C. Martius) Solms-Laubach (Pontederiaceae). They include two Eccritotarsus sources from Brazil and Peru. Distinguishing features between the two were found, necessitating their redescription. The Brazil source remained Eccritotarsus catarinensis (Carvalho), whereas the Peru source is Eccritotarsus eichhorniae Henry. Our objectives in this laboratory study were to assess the mate choice in the two species and, thus, determine which species performs better than the other. Mate choice in the form of no-choice, bichoice, and multichoice tests were conducted within and between species in a 3:1, 2:1, and 1:1 sex ratios. The E. catarinensis pair had short copula latency but long copula duration in multichoice experiments, whereas the E. eichhorniae pair had short copula latency but long copula duration in no-choice experiments. In no-choice and bichoice experiments, E. eichhorniae♀ and E. eichhorniae♂ outcompeted E. catarinensis♀ and E. catarinensis♂. In multichoice experiments, E. catarinensis♂ outcompeted E. eichhorniae♂, whereas E. eichhorniae♀ outcompeted E. catarinensis♀. Despite being shown to be more fecund, E. eichhorniae is likely not to outcompete E. catarinensis where the two species co-occur and that E. catarinensis♂ and E. eichhorniae♀ will outcompete their counterparts. Previous research indicated that when E. catarinensis♂ and E. eichhorniae♀ are crossed, they produce few offspring, underscoring the need to confirm if the two species will coexist, compete, or displace each other in their natural habitats. Our findings further support that prezygotic reproductive isolation mechanisms led to the speciation of these species.