Studies on the Acaricides Resistance of the Citrus Red Mite, Panonychus citri (McG.) IV. Genetics of Resistance to Phenkapton
1969 Volume 15 Pages 151-155
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1969 Volume 15 Pages 151-155
To analyse the genetic make-up of Phenkapton-resistance, haploid F2 eggs produced by the F1 virgin females (hybrids) of reciprocal crosses between resistant and susceptible individuals, and haploid F3 eggs produced by F2 (backcross progenies) were tested toxicologically. These eggs were dipped for 5 seconds in water solution of 1:2000 Phenkapton.
The haploid F2 eggs produced by F1 virgin females showed a high degree of non-viability which hampered further genetic analysis. In addition, the sterile female in F1 virgin female (SS×R) was about 40%. (Table 2 and 3)
The present ovicidal test suggested that one major gene was responsible for resistance to Phenkapton. However, it is a problem to determine the resistance level by the corrected egg mortality alone, because the haploid F2 eggs produced by F1 virgin females showed high degree of non-viabilty.
Therefore, adultcidal test for resistance was carried out with 1:15000 dilution of Phenkapton against the various lines of female and male adults. This concentration consistently gave 100% adult mortality of S strain and no mortality of R strain (Fig.1).
No significant difference in resistance level was found between the F1 female adults of the crosses RR×S and SS×R the mortality being 54% and 66%. Mortalities of the F2 female adults (backcross progenies) of (RR×S)×R and (SS×R)S were 24% and 74% (Table 4). The present results agreed well with the calculated values on the assumption that the F1 female adults showed 60% mortality.
We concluded that resistance to Phenkapton in Panonychus citri (McG.) was due to a single incompletely dominant gene. The character was transmitted by either sex.
