Senescence Induction on the Host Plants of Sap Sucking Insects

Abstract

In this paper the topic of the insect induced and abiotic stress induced host plant senescence is briefly discussed and the outlines of an ongoing research on the Glyceria maxima – Ischnodemus sabuleti model system are presented. Some case studies indicate that the insect induced senescence of the host plant can improve the host plant quality for the insect itself. Aggregated occurrence of the senescence inducing insects on the individual host plants can seriously enhance their damaging effects, often leading to the local eradication of the host plant. The senescence induced by the insect aggregations can lead to intraspecific and/or interspecific facilitation trough host plant quality improvement. The senescence inducing abiotic stress factors including drought and nutrient deficiency can also influence the preference and performance of the sap-sucking insects. Some current hypotheses on this topic are briefly discussed. The blissid bug species Ischnodemus sabuleti (Fallén 1826) is a phloem-feeder on the mannagrass species (Glyceria spp.) which shows aggregated spatial distribution and has a considerable senescence-inducing effect on the host plant. We investigate whether the physiological state and nutrient content of the host plant, related to the water and nutrient supply influence the preference/performance of I. sabuleti, and the effect of the mass occurrence and feeding of the I. sabuleti on the host plant.