Positive effect of drought on longicorn borer larval survivl and growth on eucalyptus trunks

Abstract

-Phoracantha semipunctata (F.) larvae attack and kill trees in Eucalyptus globulus (Labill.) plantations in Mediterranean countries. To test the hypothesis that these attacks are more likely in arid environments, we examined the effects of water deficits in the host trees of E. globulus on the mortality and growth of P. semipunctata larvae. Trees subjected to water stress during two subsequent years were compared with rainfed and irrigated trees. Larvae of P. semipunctata were artificially introduced in the bark of trees of either treatment. Larvae mortality was lower and weight gain was higher in water stressed trees than on rainfed trees. There was no larvae survival in irrigated trees. These results were related to changes in moisture content and concentration of soluble sugars in the bark of the trees. The results of this study suggest that water stress had a major role on the survival and growth of the larvae.Cerambycidae / Phoracantha semipunctata / plant-insect interaction / water-deficit / bark borer Résumé -Effets positifs de la sécheresse du sol sur la survie et la croissance des larves de Phoracantha semipunctata sur l'eucalyptus. Le Phoracantha semipunctata (F.) (Coleoptera : Cerambycidae) est un ravageur commun des plantations d'Eucalyptus globulus (Labill.) des milieux méditerranéens, particulièrement dans les régions les plus arides. La mortalité et la croissance des larves de P. semipunctata ont été comparées in vivo sur des arbres d'E. globulus soumis à trois traitements : stress hydrique durant deux années consécutives, irrigation et témoins. Des larves de P. semipunctata ont été artificiellement introduites dans l'écorce des arbres soumis aux trois traitements. Une plus faible mortalité et une augmentation de la biomasse des larves ont été obtenues chez les arbres stressés, comparativement aux arbres témoins. Chez les arbres irrigués la mortalité de larves était totale. Les effets de la teneur en eau et de la concentration en sucres solubles de l'écorce sur la mortalité larvaire ont aussi été testés. Nos résultats permettent de conclure que le stress hydrique est un facteur déterminant dans la réussite de la colonisation de l'arbre par les larves de P. semipunctata. Cerambycidae / Eucalyptus globulus / Phoracantha semipunctata / interaction plante-insecte / contrainte hydrique Ann. For. Sci. 59 (2002) [99][100][101][102][103][104][105][106] 99

Emergent insects, pathogens and drought shape changing patterns in oak decline in North America and Europe

“…Hodges and Lorio, 1969;Parker and Patton, 1975;Parker, 1979; reviewed by Mattson and Haack, 1987b;Thomas and Hodkinson, 1991;Caldeira et al, 2002;Tariq et al, 2012), with concomitant positive effects on insect development or survival (e.g. Thomas and Hodkinson, 1991;Caldeira et al, 2002;Tariq et al, 2012), it is difficult to extrapolate such effects to the scale of forest insect outbreaks (e.g. Larsson et al, 2000).…”

Detection of Longhorned Borer Attack and Assessment in Eucalyptus Plantations Using UAV Imagery

“…Upon hatching, ELB larvae bore galleries along the phloem and cambium of trees, eventually preventing sap from flowing, which leads to rapid tree death during summer and fall [1,[4][5][6]. The ability of larvae to successfully colonize the host plant depends on low bark moisture content, leaving water-stressed trees particularly susceptible to attack by ELB [1,5,7].…”

The Threat of the Combined Effect of Biotic and Abiotic Stress Factors in Forestry Under a Changing Climate

“…On the other hand, the accumulation of osmolytes and soluble sugars in response to abiotic stresses may create favorable condition for biotic stress factors such as fungal pathogens and wood boring pests thereby increasing the susceptibility of trees. In support of this, Caldeira et al (2002) reported that a reduced bark moisture content and increased accumulation of glucose, fructose, and sucrose enhanced the survival and growth of Phoracantha semipunctata under drought conditions in E. globulus. Similarly, combined drought and pathogen infection increased soluble sugar concentration in Q. brantii (Ghanbary et al, 2018) resulting in increased susceptibility to pathogens (Ghanbary et al, 2017).…”