Impact of the leaf-mining jewel beetle Hedwigiella jureceki on two forms of cat's claw creeper, Dolichandra unguis-cati

Abstract

The impact assessment of a weed biocontrol agent offers insight into the potential of the agent and weed responses in long-term weed management. The impact of the jewel beetle Hedwigiella jureceki Obenberger (Coleoptera: Buprestidae) and its first-generation larvae on the long-pod (LP) and short-pod (SP) forms of cat's claw creeper, Dolichandra unguis-cati (L.) L.G. Lohmann (Bignoniaceae) was studied by initiating one, two, or five pairs (male and female) of adults in a glasshouse experiment. With the higher density of adults, the number of leaves increased significantly, as did the numbers of dead leaves and larval mines, and the percentages of affected leaves (up to 40%), and damaged leaf areas (up to 60%). Plants with the five pairs of adults had fewer leaves and reduced dry weights (e.g., tuber biomass was reduced by 50.4–62.5%). Regardless of adult density, the dry weights of the leaves and tubers were lower in the SP form. Conversely, the LP form had fewer leaves (ca. 17% fewer) and slower shoot growth (mean ± SE = 46.3 ± 2.6 cm per week) than the SP form (66.5 ± 3.8 cm per week). However, the number of tubers was not affected by the plant form and adult density. Larval mines (262 ± 30), pupae (186 ± 17), and adults (144 ± 14) in LP form were higher than in SP form (243 ± 20, 167 ± 14, and 115 ± 11, respectively). Likewise, the average weight of adults that emerged on the LP form was higher. Therefore, H. jureceki impacted both LP and SP forms. The SP form showed a higher impact in terms of reduced tuber growth, and the LP form is anticipated to be harmed more in the long term as a higher number of H. jureceki offspring developed on it when competition for food was increased.