Fraxinus foliage: does host species during adult maturation feeding alter the fecundity of emerald ash borers, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)?

Abstract

Herbivorous insects can have their reproductive potential influenced by the quality and species of host plants they feed upon. The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive pest of ash trees (Fraxinus spp.) within its introduced range. As adults, EAB must feed upon foliage to sexually mature. We compared the influence of 4 North American ash species on EAB via foliage feeding to assess impacts on female lifespan and reproductive metrics. We fed 136 female EAB, 34 in each foliage group, either black, green, tropical, or white ash throughout their adult life. We performed daily inspections for adult mortality, oviposition, and egg hatching. We found that the mean female lifespan, fertility rate, and mean egg development time were not affected by the ash species. Potential and realized fecundity each increased with summed female group lifespan (days), but this rate differed among ash species. Consequently, there was a statistically significant interaction effect of the summed female group lifespan and the host foliage. Green ash-fed EAB laid (2.94 ± 0.86 eggs/female days) and hatched (1.67 ± 0.59 eggs/female days) the most eggs, more than double the rates of EAB feeding on black (1.39 ± 0.48 laid and 0.75 ± 0.30 hatched eggs/female days) and white (1.08 ± 0.35 laid and 0.65 ± 0.22 hatched eggs/female days) ash. Adults feeding on green ash resulted in the greatest EAB fecundity suggesting that the presence of green ash may promote population growth and provide a pathway to overwhelm other ash species nearby.