Effect of radiation on fecundity and fertility of codling moth Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) from South Africa

Abstract

Codling moth Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) is the key pest of pome fruit in South Africa, and it’s control in apple and pear orchards relies on the application of insecticides and pheromone‐mediated mating disruption. Development of resistance to insecticides and placement of restrictions on the use of certain insecticides has made control of codling moth in South Africa increasingly problematic. The use of the sterile insect technique (SIT) as a control tactic for codling moth is under investigation as a potential addition to the current control strategy. We investigated the radiosensitivity of a laboratory strain of codling moth that was established from moths collected from commercial and organic orchards in the Western Cape, South Africa. Fecundity and fertility of this strain following radiation were consistent with values for the codling moth strain in the Canadian rearing facility in British Columbia. For both strains, the female codling moth was considerably more radiosensitive than the male. At a radiation dose of 100 Gy or higher, treated females were 100% sterile. The fertility of the South African strain was higher (86.3%) than for the Canadian strain (71.9%). This difference in fertility between the two strains was maintained when the dose of radiation was 100 Gy. However, the level of fertility was very similar between the two strains for doses ≥150 Gy. Therefore, based upon previously published work and the data from this study, an operational dose of 150 Gy is recommended for future codling moth SIT programmes in South Africa.

Gamma irradiation of the carob or date moth Ectomyelois ceratoniae: dose–response effects on egg hatch, fecundity, and survival

“…() for the cactus moth Cactoblastis cactorum (Berg). Declining parental fecundity was associated with increasing doses of irradiation in our study, which is congruent with previously reported studies conducted on treated female codling moth, C. pomonella (Bloem et al., ; Blomefield et al., ). Fecundity data of the F1 generation of carob moth in our study were similar to those obtained with the sugar cane borer, Diatraea saccharalis Fabricius (Sanford, , ), the Oriental leaf worm moth, Spodoptera litura Fabricius (Seth & Sharma, ), and the false codling moth, T. leucotreta (Bloem et al., ), i.e., a significant decline in fecundity of F1 males and females with increasing doses of radiation applied to parent males.…”

Improvement of the sterile insect technique for codling moth Cydia pomonella (Linnaeus) (Lepidoptera Tortricidae) to facilitate expansion of field application

“…Fecundity of 100 Gy‐irradiated females was reduced by more than 30% as compared with non‐irradiated females and their fertility, estimated by the proportion of hatching eggs, was almost zero. The viability of the eggs produced by non‐irradiated females mated with 100 Gy‐irradiated males was 36% lower than that obtained from the untreated mating (Botto and Glaz 2009), which is similar to the data obtained for male moths treated with 100 Gy in South Africa (64.4% residual fertility) (Blomefield et al. 2009) but higher than those obtained for Canadian male moths (49% residual fertility) (Bloem et al.…”

“…female moths of both strains were more radiosensitive than the male moths and female moths treated with 100 Gy (or higher) were 100% sterile. However, laboratory moths from South Africa were less sensitive than those of Canada, and this difference was maintained when a dose of 100 Gy was administered but disappeared when the dose was higher (Blomefield et al. 2009).…”

Comparison of laboratory and field bioassays of laboratory‐reared Cydia pomonella (Lepidoptera: Tortricidae) quality and field performance

“…The operational dose of radiation for the Entomon SIT programme (Addison and Henrico ; Blomefield et al. ) is 150 Gy. Radiation dose treatments for all bioassays in this study were 0, 150, 300 and 450 Gy.…”