Author/Editor		Žunič, Alenka; Čokl, Andrej; Serša, Gregor
Title		Effects of 5-Gy irradiation on fertility and mating behaviour of Nezara viridula (Heteroptera: Pentatomidae)
Translated title		Vpliv obsevanja z dozo 5 Gy na plodnost in paritveno vedenje pri vrsti Nezara viridula (Heteroptera, Pentatomidae)
Type		članek
Source		Radiol Oncol
Vol. and No.		Letnik 36, št. 3
Publication year		2002
Volume		str. 231-7
Language		eng
Abstract		Background. The polyphagous and cosmopolitan species Nezara viridula is one of the most important insect pests. The sterile insect technique (SIT) is a pest control strategy that involves sterilising males by exposing them to ionising radiation. Sterile males, released into wild population, mate with females, but eggs are not fertilised and the population gradually declines. Exposing insects to radiation during their growth stage might require lower sterilising dose. The aim of our study was to test whether 5-Gy irradiation of 5th instar nymphs significantly affects: (1) moulting and further development of the irradiated nymphs, (2) the male's and female's reproduetive system and (3) the mating competitiveness of treated males, with special focus on vibrational communication. Methods: The 5th instar nymphs were irradiated with 5 Gy using X ray generator and monitored daily. Results: The observed effects of irradiation were: prolonged moulting increased mortality during development and during the first day of adult life, decreased males to females ratio, decreased fecundity, egg production, proportion of fertile eggs and progeny survival. The reaction of a male to stimulation with the model female calling song was tested. The irradiated and non-irradiated males responded to stimulation with emission of the eourtship song (MCrS). Temporal parameters of MCrS emitted by non-irradiated males differed when compared with those of irradiated ones. Conclusions: The 5-Gy irradiation of 5th instar nymphs did not affect mating behaviour. However since the irradiation during growth stage decreased the fertility and fecundity of emerged adults, this technique, in combination with certain other suppression teehniques, could be a successful control strategy for management of Nezara viridula. On the other hand observed effects on moulting and further development of the irradiated nymphs could decrease the efficiency and application of this strategy.
Summary		Uvod. Žuželka Nezara viridula je zaradi polifagne narave prehranjevanja pomemben škodljivec po vsem svetu. Tehnika uporabe sterilnih žuželk (SIT) je metoda nadziranja velikosti populacije, ki vključuje sterilizacijo z obsevanjem. Sterilni samci se v naravni populaciji parijo s samicami, le-te pa odložijo neoplojena jajčeca. To ima za posledico postopen upad velikosti populacije. Testirali smo hipotezo, da bi bile doze potrebne za sterilizacijo nižje, če bi sevanju izpostavili ličinke namesto odraslih živali. Namen naše raziskave je bil ugotoviti ali obsevanje ličink v 5. stadiju z dozo 5 Gy značilno vpliva na: (1) levitev in razvoj obsevanih ličink, (2) reprodukcijski sistem razvitih samcev in samic, (3) kompetativnost samcev in vibracijsko komunikacijo. Metode. Ličinke 5. stadija smo z uporabo rentgenskega aparata obsevali z dozo 5 Gy in vsakodnevno spremljali njihov razvoj. Rezultati. Sevanje je podaljšalo obdobje levitve, povečala se je smrtnost nimf med levitvijo in odraslih prvi dan po preobrazbi, število razvitih samcev je bilo manjše. Po obsevanju je rodnost upadla, produkcija in delež oplojenih jajčec sta se zmanjšala, povečala se je smrtnost potomcev. Preverili smo tudi odziv samcev na umetni napev samice (dražljaj). Tako obsevani kot neobsevani samci so se na dražljaj odzvali z emisijo napeva dvorjenja (MCrS). Casovni parametri MCrS so se pomembno razlikovali tako med neobsevanimi kot tudi med neobsevanimi in obsevanimi samci. Zaključki. Obsevanje z dozo 5 Gy ni vplivalo na paritveno vedenje je pa zmanjšalo plodnost in rodnost razvitih odraslih, zato bi bila ta tehnika v kombinaciji z drugimi tehnikami zatiranja, lahko uspešna pri nadzoru velikosti populacije vrste Nezara viridula. Vpliv sevanja na levitev in razvoj ličink pa bi lahko zmanjšal učinkovitost in uporabo te tehnike.
Descriptors		GRYLLIDAE INSECT CONTROL MOLTING ANIMAL COMMUNICATION VIBRATION