Abstract: The olive fruit fly, Bactrocera oleae Gmelin (Diptera: Tephritidae), is one of the most serious pests in olive orchards in growing province in Iran. The female lay eggs in green olive fruit and larvae hatch inside the fruit, where they feed upon the fruit matters. One of the main ecologically friendly and species-specific systems of pest control is the sterile insect technique (SIT) which is based on the release of large numbers of sterilized insects. The objective of our work was to develop a SIT against B. oleae by using of gamma radiation for the laboratory and field trial in Iran. Oviposition of female mated by irradiated males is one of the main parameters to determine achievement of SIT. To conclude the sterile dose, pupae were placed under 0 to 160 Gy of gamma radiation. The main factor in SIT is the productivity of females which are mated by irradiated males. The emerged adults from irradiated pupae were mated with untreated adults of the same age by confining them inside the transparent cages. The fecundity of the irradiated males mated with non-irradiated females was decreased with the increasing radiation dose level. It was observed that the number of eggs and also the percentage of the egg hatching was significantly (P < 0.05) affected in either IM x NF crosses compared with NM x NF crosses in F1 generation at all doses. Also, the statistical analysis showed a significant difference (P < 0.05) in the mean number of eggs laid between irradiated and non-irradiated females crossed with irradiated males, which suggests that the males were susceptible to gamma radiation. The egg hatching percentage declined markedly with the increase of the radiation dose of the treated males in mating trials which demonstrated that egg hatch rate was dose dependent. Our results specified that gamma radiation affects the longevity of irradiated B. oleae larvae (established from irradiated pupae) and significantly increased their larval duration. Results show the gamma radiation, and SIT can be used successfully against olive fruit flies.
Abstract: Studies regarding the determination of population
trend of Lipaphis erysimi (kalt.) and its associated natural enemies in
different Brassica lines along with the effect of gamma radiation on
their population were conducted at Agricultural Research Farm,
Malakandher, Khyber Pakhtunkhwa Agricultural University
Peshawar during spring 2006. Three different Brassica lines F6B3,
F6B6 and F6B7 were used, which were replicated four times in
Randomized Complete Block Design. The data revealed that aphid
infestation invariably stated in all three varieties during last week of
February 2006 (1st observation). The peak population of 4.39 aphids
leaf-1 was s recorded during 2nd week of March and lowest population
of 1.02 aphids leaf-1 was recorded during 5th week of March. The
species of lady bird beetle (Coccinella septempunctata) and Syrphid
fly (Syrphus balteatus) first appeared on 24th February with a mean
number of 0.40 lady bird beetle leaf-1 and 0.87 Syrphid fly leaf-1,
respectively. At the time when aphid population started to increase
the peak population of C. septempunctata (0.70 lady bird beetle leaf-
1) and S. balteatus (1.04 syrphid fly leaf-1) was recorded on the 2nd
week of March. Chrysoperla carnea appeared in the 1st week of
March and their peak population was recorded during the 3rd week of
March with mean population of 1.46 C. carnea leaf-1. Among all the
Brassica lines, F6B7 showed comparatively more resistance as
compared to F6B3 F6B6. F6B3 showed least resistance against L.
erysimi, which was found to be the most susceptible cultivar. F6B7
was also found superior in terms of natural enemies. Maximum
number of all natural enemies was recorded on this variety followed
by F6B6. Lowest number of natural enemies was recorded in F6B3.
No significant effect was recorded for the effect of gamma radiation
on the population of aphids, natural enemies and on the varieties.