Physiological Response of Orchids to Mealybugs (Hemiptera: Pseudococcidae) Infestation

Abstract

The harmfulness of mealybugs resulting from sucking plant sap, secreting honeydew, and transmitting plant viruses can give them the status of serious pests. This study documents the influence of Pseudococcus maritimus (Ehrhorn) and Pseudococcus longispinus (Targioni Tozzetti) infestation on alterations in selected physiological parameters of Phalaenopsis x hybridum 'Innocence'. The condition of the cytoplasmic membranes was expressed as the value of thiobarbituric acid reactive substances. We have determined changes in the activities of catalase and guaiacol peroxidase and measured the following chlorophyll fluorescence parameters: maximum quantum yield of photosystem II (Fv/Fm), effective quantum yield (Y), photochemical quenching (qP), and nonphotochemical quenching (qN). The strongest physiological response of orchids was recorded in the initial period of mealybugs infestation. Prolonged insect feeding suppressed lipid peroxidation, peroxidase and catalase activity, as well as photosynthesis photochemistry. The pattern of changes was dependent on mealybug species. This indicated the complexity of the processes responsible for plant tolerance. Data generated in this study have provided a better understanding of the impact of two mealybug species infestation on Phalaenopsis and should be useful in developing pest management strategies.

Defense Responses in the Interactions between Medicinal Plants from Lamiaceae Family and the Two-Spotted Spider Mite Tetranychus urticae Koch (Acari: Tetranychidae)

“…However, a significant increase, compared to control, was noted after two weeks of T. urticae feeding on O. basilicum, after one week on M. officinalis and after 1 day on S. officinalis. Long-term feeding of two-spotted mites on M. officinalis and S. officinalis decreased GPX activity, as in the case of scale insect [33] and aphid [31] feeding.…”

“…ROS may initiate destructive oxidative processes, such as chlorophyll bleaching, lipid peroxidation, protein oxidation, and nucleic acid damage, eventually leading to cell death [16,28,29]. However, plants have antioxidant mechanisms to scavenge excess ROS and prevent cell damages [30][31][32][33][34]. Low molecular weight antioxidants (ascorbic acid, glutathione and tocopherols) and ROS-scavenging enzymes have the capacity to scavenge superoxides, hydroxyl radicals and singlet oxygen [35,36].…”

Effect ofNeuroterus quercusbaccarum(L.) galls on physiological and biochemical response ofQuercus roburleaves

“…For example, the presence of aphid galls (Kmieć et al ., 2018), midge galls (Nabity et al ., 2012), cynipid wasp galls (Kot et al ., 2018 b ) as well as aphids on barley (Gutsche et al ., 2009) caused a significant reduction of Y values. On the other hand, plants infested by scale insects showed increased (Retuerto et al ., 2004) or decreased (Kmieć et al ., 2016) values of this parameter.…”

“…Fluorescence quenching parameters, such as photochemical ( q P ) and non-photochemical quenching ( q N ) coefficients are commonly used as indicators of plant stress exposed to insect feeding (Gutsche et al ., 2009; Golan et al , 2015; Kmieć et al ., 2016). However, it seems that q N is a much more sensitive indicator of a stress response than q P (Juneau et al ., 2005).…”