Effects of Longer Droughts on Holm Oak Quercus ilex L. Acorn Pests: Consequences for Infestation Rates, Seed Biomass and Embryo Survival

Abstract

The effects of climate change on oaks Quercus spp. constitute a main environmental concern for the conservation of temperate forests. In this context, we assessed the consequences of longer droughts on the interactions between the holm oak Quercus ilex L. and its main acorn pests. Infested acorns were prematurely abscised before reaching their potential size. The volume of the acorns attacked by Cydia fagiglandana (Lepidoptera) was smaller than those attacked by Curculio elephas (Coleoptera); however, their weight did not differ because Curculio larvae consumed more cotyledon. For the same reason, embryo survival likelihood was not lower in Cydia acorns despite their smaller size. Delays of late summer rain reduced infestation by Curculio, as soil hardness hampers adult emergence from their underground cells. By contrast, late and scarce precipitations benefited Cydia; rainfall might hamper adult flight and eggs/L1 larvae survival. There was not a “zero-sum” effect, because the decrease of Curculio infestation rates was not fully compensated by an increase of Cydia. Under the longer droughts projected for the Mediterranean Basin, our results predict lower infestation rates and higher acorn survival likelihood. However, further studies including other environmental factors are needed to better forecast the net consequences for holm oak fitness.

Fragmentation and Connectivity in dehesa Ecosystems Associated with Cerambyx spp. Dispersion and Control: A Graph-Theory Approach

“…An example is seed dispersal through jays' acorn dispersal and burial [80,81]. Another example is the predation of other important pests in dehesa such as Curculio elephas Gyl., or caterpillars from the Lepidoptera order such as Cydia fagiglandana Zeller [82].…”

Cholomyia inaequipes1 Como Parasitoide de Dos Curculiónidos Asociados con Las Bellotas de Encinos en el Estado de México, México

“…Diversas especies de picudos incluidos en los géneros Curculio L., y Conotrachelus Dejean (Coleoptera: Curculionidae), así como Cydia Hübner (Lepidoptera: Tortricidae) están implicados en el fenómeno denominado “depredación-predispersión” que ocurre en las bellotas inmaduras de numerosas especies de encinos ( Quercus L.: Fagaceae) (Canelo et al 2021, Steele et al 2021). Sus larvas son espermatófagas y permanecen en el interior de las bellotas hasta concluir su desarrollo.…”

Effects of livestock on arthropod biodiversity in Iberian Holm oak savannas revealed by metabarcoding

“…As in any other agricultural system, pest insects reduce the productivity in oak dehesas (Canelo et al, 2021a), but the preservation of their high natural value preclude the use of any chemical treatment. Current approaches follow the logic of ecological intensification, based on managing service-providing organisms that make a quantifiable direct or indirect contribution to agricultural and forest productivity (Bommarco et al, 2013;Montesinos, 2019).…”