Variability in diapause attributes of the citrus red mite, Panonychus citri and its population dynamics

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There are two strains of the citrus red mite, Panonychus citri: one is a diapausing strain that occurs only on deciduous fruit trees and the other a non-diapausing strain that occurs both on citrus and deciduous fruit trees.1. The two strains are reproductively incompatible in that no Fl adult females are produced from the cross between them. 2. Mating is common between the strains, although copulation is often broken off prematurely between C <+!゜> x DP <^!゜> . 3. There is a reciprocal difference in the reproductive incompatibility; the hatchability of the eggs from the cross between DP <+!゜> x C <^!゜> is significantly lower that between c <+!゜> x dp <^!゜> . 4. Mating is in most cases ineffective for the females that mated with a male of the other strain. In particular, for the DP females that mated first with C males, the subsequent intra-strain mating is almost entirely ineffective. 5. The DP males show a strong mating preference to the females of their strain, whereas the C males do not show any such preference. 6. Under the coexistence of both strains, the effective mating rate was lower than 50% for the females of both strains, clearly showing a mating interference between them. 7. The non-diapausing strain does not successfully overwinter on deciduous fruit trees, showing that the occurrence is due to the immigration from citrus or other evergreen trees. 8. In the intermediate latitudal zones in Japan, the two strains coexist in some pear orchards. In such pear orchards, the proportion of females in the spring DP population is very low and its occurrence is often suppressed. This seems due to an adverse effect of the inter-strain mating mentioned above.