Delayed mating in tortricid leafroller species: simultaneously aging both sexes prior to mating is more detrimental to female reproductive potential than aging either sex alone

Abstract

AbstractThe effect of delayed mating on reproductive potential, longevity and oviposition period of female redbanded leafroller,Argyrotaenia velutinana(Walker) and Pandemis leafroller,Pandemis pyrusanaKearfott, was investigated in the laboratory. Virgin female or male moths of each species were held for 1, 2, 4, 6 or 10 days prior to pairing with one-day-old virgin conspecifics of the opposite sex. In addition, reproductive potential was assessed when both sexes of each species were aged for those periods prior to pairing. The expected reproduction of femaleA. velutinanawas reduced by 34, 53, 71 and 81% for 2, 4, 6 and 10-day delays in female mating, respectively. ForP. pyrusana, expected reproduction was reduced by 47, 74, 85 and 93% for 2, 4, 6 and 10-day delays in female mating, respectively. Increasing male age at mating in both species had a lesser effect on female reproductive output compared with increasing female age at mating. As maleA. velutinanaage at mating increased, the expected reproduction of femaleA. velutinanawas reduced by 15, 45, 54 and 70% for 2, 4, 6 and 10-day delays, respectively. Comparing maleP. pyrusanaof various ages at mating, expected reproduction was reduced by 14, 42, 64 and 79% for 2, 4, 6 and 10-day delays in mating, respectively. The decrease in female reproduction when both sexes were aged prior to mating was higher than when either sex alone was aged prior to pairing with a one-day-old virgin of the opposite sex. The expected reproduction of femaleA. velutinanawas reduced by 60, 83, 96 and 98% for 2, 4, 6 and 10-day delays in mating of both sexes, respectively. Only 7.5% of female eggs hatched when both sexes ofA. velutinanawere aged ten days prior to mating. When simultaneously aging both sexes ofP. pyrusanaprior to mating, expected reproduction was reduced by 71, 93, 96 and 99% for 2, 4, 6 and 10-day delays in mating, respectively. NoP. pyrusanaeggs hatched after a ten-day delay of mating for both sexes. For both species, female longevity increased and duration of oviposition period decreased with increasing female age at mating. Our results demonstrate that delayed mating in both females and males negatively affects female reproductive output in both species and that simultaneous aging of both sexes prior to mating has a greater effect than aging either sex alone. Our results suggest that laboratory studies that have paired aged females or aged males with conspecifics of optimal reproductive maturity have likely underestimated the effects of delayed mating on reproductive output.