Mathenge C W, Holford P, Hoffmann J H, Zimmermann H G, Spooner-Hart R N, Beattie G A C
Zoology Department, University of Cape Town, Private Bag X3, Rondebosch 7701, Cape Town, South Africa.
Bull Entomol Res. 2010 Jun;100(3):331-8. doi: 10.1017/S0007485309990344. Epub 2010 Jan 15.
Dactylopius tomentosus is composed of biotypes adapted to different Cylindropuntia species. One biotype is an important biological control agent of C. imbricata in South Africa while another has the potential for the control of C. fulgida var. fulgida. These two weed species occur in sympatry in some areas of South Africa, so the introduction of the second biotype could result in hybridization, which, in turn, could impact on the biological control programs through altered host specificity and fitness of the hybrids. To anticipate what might happen, reciprocal crosses were made between the two biotypes, and the biological performance of the resultant hybrids was compared with that of each parental lineage on C. imbricata and C. f. var. fulgida. The biotypes interbred freely and reciprocally in the laboratory. Comparisons of crawler and adult female traits showed differences in performance that were dependent on the origin of the maternal and paternal genomes. However, when all traits were combined into a 'fitness index', both hybrids clearly outperformed the parental lineages. The increase in fitness shown by the hybrids over their maternal lineage was greater on the alternative host of the maternal parent than on the natural host of the maternal parent. Therefore, in areas where the two cacti occur in sympatry, hybridization between the biotypes is not expected to be detrimental to the biological control of either weed.
绒毛仙人掌粉蚧由适应不同圆柱仙人掌属物种的生物型组成。其中一种生物型是南非仙人掌科肉质植物的重要生物防治剂，而另一种生物型有控制富刺仙人掌变种富刺仙人掌的潜力。这两种杂草物种在南非的一些地区同域分布，因此引入第二种生物型可能会导致杂交，进而可能通过改变杂种的宿主特异性和适应性影响生物防治计划。为了预测可能发生的情况，对这两种生物型进行了正反交，并将所得杂种的生物学表现与每个亲本谱系在仙人掌科肉质植物和富刺仙人掌变种上的表现进行了比较。这两种生物型在实验室中能自由地进行正反交。对若虫和成年雌虫性状的比较表明，其表现存在差异，这取决于母本和父本基因组的来源。然而，当所有性状合并为一个“适合度指数”时，两种杂种的表现均明显优于亲本谱系。杂种相对于其母本谱系在适合度上的增加，在母本的替代宿主上比在母本的天然宿主上更大。因此，在两种仙人掌同域分布的地区，预计生物型之间的杂交不会对任何一种杂草的生物防治产生不利影响。
