Fiziološko prilagođavanje larvi gubara, Lymantria dispar L., i žutotrbe, Euproctis chrysorrhoea L., (Lepidoptera) na delovanje fluorantena

Abstract

Fluoranten je jedan od najrasprostranjenijih policikličnih aromatičnih ugljovodonika, prisutan u lišću različitih biljaka kojima se hrane larve polifagnih vrsta insekata Lymantria dispar i Euproctis chrysorrhoea. Cilj ove doktorske disertacije je sticanje uvida u obrasce fizioloških odgovora larvi L. dispar i E. chrysorrhoea (Lepidoptera: Erebidae) na prisustvo sredinski relevantnih koncentracija fluorantena u hrani i rasvetljavanje mehanizama odbrane od njegovog štetnog delovanja, što doprinosi sagledavanju načina njihovog prilagođavanja stresnim uslovima u okruženju. Ispitivan je hronični uticaj dve koncentracije fluorantena (6,7 i 67 ng/g suve mase hrane) na larve L. dispar i E. chrysorrhoea, poreklom iz prirodnih populacija. Antioksidativni i detoksifikacioni enzimi srednjeg creva larvi su pokazali promene aktivnosti pod uticajem fluorantena, sa izraženijim odgovorima u tkivu srednjeg creva, kao i razlike u obrascima odgovora između vrsta. Uočeno je smanjenje ekspresije Hsp70 u celom srednjem crevu, a različiti odgovori Hsp70 u mozgu larvi. Kod obe vrste je došlo i do značajnih promena aktivnosti digestivnih enzima i njihovih izoformi u srednjem crevu larvi izlaganih fluorantenu. Detektovana je inhibicija aktivnosti određenih digestivnih enzima i njihovih izoformi kod larvi L. dispar, dok je kod larvi E. chrysorrhoea zabeleženo povećanje aktivnosti većeg broja enzima ove grupe, kao i ekspresija izoformi pojedinih enzima kod larvi izlaganih fluorantenu. Kanonijskom diskriminacionom analizom su potvrđene razlike između vrsta kada su u pitanju odgovori antioksidativnih i digestivnih enzima na prisustvo fluorantena u ishrani. Alokacija energetskih resursa ka mehanizmima odbrane, u prisustvu fluorantena, odrazila se na osobine životne istorije larvi obe vrste.

Fluoranthene is one of the most abundant polycyclic aromatic hydrocarbons, present in the leaves of various plants used for food by larvae of polyphagous insect species Lymantria dispar and Euproctis chrysorrhoea. The aim of dissertation was to gain insight into the patterns of physiological responses of L. dispar and E. chrysorrhoea larvae (Lepidoptera: Erebidae) to the presence of environmentally relevant concentrations of fluoranthene in food and to elucidate the mechanisms of defense against its harmful effects, which contributes to perceive the way they adjust to stressful environmental conditions. Chronic effects of fluoranthene (6.7 and 67 ng/g dry food weight) on L. dispar and E. chrysorrhoea larvae, originating from natural populations, were examined. Antioxidative and detoxification enzymes of midgut showed changes of activity under the influence of fluoranthene, with more pronounced responses in midgut tissue, and between-species differences in patterns of responses. Decreased expression of Hsp70 in the midgut, and different responses of Hsp70 in the brain of larvae were noticed. Significant changes of the activity of digestive enzymes and their isoforms in the midgut of larvae of both species exposed to fluoranthene were noticed. Exposure to fluorantene inhibited the activity of certain digestive enzymes and their isoforms of L. dispar larvae, and increased the activity of a number of enzymes and expression of isoforms of certain enzymes of E. chrysorrhoea larvae. Canonical discriminant analysis confirmed between-species differences in responses of antioxidative and digestive enzymes to the presence of fluoranthene in the diet. The allocation of energy resources to defense mechanisms affected the life history traits of treated larvae of both species.