Effective Defense of Aleppo Pine Against the Giant Scale Marchalina hellenica Through Ecophysiological and Metabolic Changes

Aleppo pine (Pinus halepensis) is widely distributed in the Mediterranean region and in other areas of the world, where it has been introduced due to its adaptive capacity to xerothermic conditions. The giant pine scale Marchalina hellenica often infests Aleppo pine, as well as other pines, in several southeastern European countries, causing pine declines. When combined with the expected intensified heat and drought events in eastern Mediterranean, the impact of this biotic parameter on the host pines may be exacerbated. The importance of understanding the defense mechanisms of Aleppo pine is emphasized by the recent invasion of the pine scale in new regions, like Australia, lacking the insect’s natural enemies, where more intense negative effects on pine species may occur. To date, Aleppo pine’s physiological responses to the infestation by M. hellenica are largely unknown. This study aimed at assessing the responses of Aleppo pine to the giant pine scale attack, both on an ecophysiological and a metabolic level. For this purpose, gas exchange, needle water status, and carbon and nitrogen content were measured during 1 year on healthy and infested adult trees. M etabolic profiling of Aleppo pine needles was also performed before, during, and after the high feeding activity of the insect. The maintenance of stable relative water content, δ13C signatures, and chlorophyll fluorescence in the needles of infested pines indicated that infestation did not induce drought stress to the host pines. At the peak of infestation, stomatal closure and a pronounced reduction in assimilation were observed and were associated with the accumulation of sugars in the needles, probably due to impaired phloem loading. At the end of the infestation period, tricarboxylic acids were induced and phenolic compounds were enhanced in the needles of infested pines. These metabolic responses, together with the recovery of photosynthesis after the end of M. hellenica intense feeding, indicate that in the studied region and under the current climate, Aleppo pine is resilient to the infestation by the giant pine scale. Future research should assess whether these promising defense mechanisms are also employed by other host pines, particularly in regions of the world recently invaded by the giant pine scale, as well as under more xerothermic regimes.

Honeydew producing insects in some forests of Turkey and their potential to produce of honeydew honey

The commercial interest in honeydew honey is increasing because of its higher therapeutic properties than most flower-based honeys. Marchalina hellenica Gennadius (Hemiptera: Marchalinidae) is one of the important scale insects to produce of honeydew honey and its honeydew in large quantities is collected by honeybees and used in pine honey in Turkey. The aim of this study was to survey and identify honeydew producing insects’ habitats that source of honeydew honey in pure fir forest in Bolu, spruce forests in Giresun (Black Sea region), oaks forest in Kırklareli (Thracian region) and cedar forest in Antalya (Mediterranean region). In accordance with these results, we found 20 honeydew producers and among of them are Cinara cedri Mimeur on Cedrus libani, Marchalina caucasica Hadzibejli on Abies nordmanniana subsp nordmanniana, and Picea orientalis; Nemolecanium abietis Borchsenius, Physokermes hellenicus Kozẚr & Gounari and Schizolachnus pineti on Abies bornmuelleriana; Lachnus roboris Linnaeus and Parthenolecanium rufulum (Cockerell) on Quercus spp. and Castanea sativa; Metcalfa pruinosa Say (Hemiptera: Flatidae) and Ricania simulans (Walker) (Hemiptera: Ricaniidae) on different host plants. All these insects produce large amount of honeydew depending on their population size. The article discusses the potential for these insects to produce honeydew honey. Keywords: Picea orientalis, Abies nordmanniana, Ricania simulans, Eulecanium sericeum Metcalfa pruinosa, Marchalina caucasica

Seasonal development and ovipositing behavior of Marchalina hellenica (Hemiptera: Margarodidae)

Marchalina hellenica, Gennadius (Hemiptera: Margarodidae) is the main honeydew producing insect of pine trees ίη Greece. Its behavior during oviposition, the reproductive capacity, oviposition period, pre-hatching period, and life span of the οviposited female and other aspects of its reproductive behavior in the field and in the laboratory, have been recorded in a three-year research. Μ. hellenica completes one generation per year. It is mainly parthenogenetic. The adult female appears on the trees, looking for an oviposition site from late March to late April. Its oviposition period in the field lasts about 20 days, while the hatching period lasts about 30 days. Live females can be found on the trees until the end of May, so there is a coexistence of three stages of Μ. hellenica, adult, eggs and 151 stage nymphs, in the field for about one month. Μ. hellenica is able to oviposit in the laboratory in room conditions. Its ovipositing period is as long as 16 days, while the total number of eggs laid is on average 262. Body weight was significantly correlated with the total number of eggs laid.