Rearing of the fruit fly parasitoidDiachasmimorpha longicaudata(Hymenoptera: Braconidae) on X-ray irradiated larvae ofCeratitis capitata(Diptera: Tephritidae)

Abstract

2012) Rearing of the fruit fly parasitoid Diachasmimorpha longicaudata (Hymenoptera: Braconidae) on X-ray irradiated larvae of Ceratitis capitata (Diptera: Tephritidae), We evaluated the effects of X-ray irradiation on larvae of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), with the aim of finding a treatment that prevented adult fly emergence, yet did not adversely affect larval quality as rearing hosts for the parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Ichneumonidae). Two experiments were carried out. In the first experiment, small numbers of larvae were held in Petri dishes with and without small amounts of rearing media and then irradiated with doses of X-rays ranging from 0 to 8333.6 R (equivalent to 80 Gy). In the second experiment, higher numbers of larvae were held in a manner resembling mass-rearing conditions, and were then irradiated with X-rays ranging from 0 to 10,417 R (equivalent to 100 Gy). In both experiments, the only factor that significantly affected fly emergence was irradiation of larvae. Fly emergence decreased markedly as the irradiation dose increased, and complete suppression of fly emergence was achieved at 6250.2 R (equivalent to 60 Gy) when larvae were irradiated in small batches with or without rearing media. Irradiation also affected the fertility of those flies that did emerge following treatment. In the second experiment, we found the parasitoids reared from irradiated larvae produced a higher parasitism rate and a higher number of female offspring than did parasitoids reared from control (nonirradiated) larvae. Mean fecundity of F1 parasitoids reared from irradiated larvae were affected positively by irradiation only at the 8333.6 R (80 Gy) dose. Our results show that X-ray irradiation can be used to inhibit fruit fly adult emergence and that irradiated larvae are at least as good a rearing substrate as nonirradiated larvae. Future studies should focus on the adjustment of our findings to a mass-rearing scale.

Irradiation ofAnastrepha fraterculus(Diptera: Tephritidae) Eggs to Inhibit Fly Emergence in the Mass-Rearing ofDiachasmimorpha longicaudata(Hymenoptera: Braconidae)

“…Larvae of A. obliqua (Macquart), A. serpentina (Wiedemann), and A. ludens (Loew) are routinely gamma rayed for the mass-rearing of tens of millions of parasitoids ( Cancino et al 2009b ), ensuring shipments clean of adult flies. Viscarret et al (2012) and Bachmann et al (2015) showed that C. capitata and A. fraterculus larvae irradiated with X-rays are also suitable for the rearing of D. longicaudata in Argentina. The irradiation of host eggs instead of larvae is an important alternative in the mass-rearing of fruit fly parasitoids ( Cancino et al 2009a ), but little work has been done with Anastrepha spp.…”

Application of Nuclear Techniques to Improve the Mass Production and Management of Fruit Fly Parasitoids

“…Some evidence likewise indicates that fruit fly larvae are immunologically compromised, thus radiation can result in a higher percent of parasitoid emergence. Diachasmimorpha longicaudata emergence and females-biased sex ratio increased following exposure of both C. capitata and A. fraterculus hosts to X-ray doses of between 20 Gy and 100 Gy [ 45 , 46 ]. Gamma irradiated C. capitata larvae also supported higher D. longicaudata emergence rates and produced a significantly greater proportion of females [ 66 , 67 ].…”

“…For example, a dose of 60 Gy applied to 150–200 third instar C. capitata placed in a Petri dish, completely inhibits adult fly emergence, whether or not larvae are immersed in diet. However, adult development and eclosion of ~19,000 larvae in a larger container was not completely suppressed even with a dose 100 Gy [ 45 ]. X-rays have lower penetration than gamma rays [ 43 ] and their efficiency is greatly reduced when larvae are immersed in diet and presented in deep-bodied trays.…”

“…[ 42 ] compared the use of gamma and X-rays to induce sterility in C. capitata and Anastrepha fraterculus (Wiedemann), the South American fruit fly, and obtained 99% sterility in both species. Further studies on C. capitata and A. fraterculus exposure to X-rays [ 45 , 46 ] find that larval volume/density within the irradiation device affects even more than gamma radiation dosage formulations [ 19 , 44 , 47 ]. This kind of X-ray irradiation represents an important alternative technology in parasitoid mass rearing, but it will be necessary to reevaluate doses and methods.…”

Evaluation of volumes of Ceratitis capitata larvae in exposure devices to Diachasmimorpha longicaudata in mass rearing conditions in Costa Rica

“…The use of irradiation occurs because the hosts are not 100% parasitized, so it is irradiated to prevent larvae that have not been parasitized from emerging, contaminating the release site. For this, irradiating equipment is required, gamma ray irradiators are commonly used (Cancino et al, 2002, Viscarret et al, 2012, but X-rays are used in Costa Rica, since they handle low volumes of production in comparison with Mexico, and the purchase of this type of equipment is much simpler. However, when the equipment is damaged, the spare parts are very expensive and specialized technicians that can repair the equipment in the country is scarce.…”