Abstract
Damage caused to cultivated carrots by the hawthorn-carrot aphid, Dysaphis crataegi Kalt. (Hemiptera: Aphididae) is one of the factors limiting carrot production in Poland. Planting resistant and tolerant cultivars could reduce yield losses due to the damage caused by this pest. This study was conducted to evaluate the resistance and/or tolerance of 10 carrot genotypes to hawthorn-carrot aphid. Their field resistance was determined under field conditions based on five indicators, namely, mean number of alates (migrants) per plant and mean percentage of plants colonized by them, mean seasonal number of aphids per plant, mean number of aphids per plant and mean percentage of infested plants at peak abundance. Antibiosis experiments were conducted under laboratory conditions and pre-reproductive, reproductive time, fertility, and demographic parameters, represented by the net reproduction rate (Ro), intrinsic rate of increase (rm) and mean generation time (T), were calculated. Five cultivars, Afro F1, Nipomo F1, Samba F1, White Satin F1, and Yellowstone showed field resistance. Antibiosis experiments revealed significant differences among the carrot cultivars in the length of the reproductive period, female fecundity in the time equal to the pre-reproduction time, and total progeny of hawthorn-carrot aphid. The intrinsic rate of natural increase (rm) for apterous aphids varied significantly, ranging between 0.181 (Nipomo F1) and 0.343 females/female/day (White Satin F1). Additionally, the estimated net reproductive rate (R0) was the lowest on Nipomo F1, and this genotype was determined to be resistant. Our results suggest that a very high density of trichomes on the leaf petioles (71.94 trichomes/cm2) could adversely affect the feeding, bionomy, and demographic parameters of hawthorn-carrot aphid on the cultivar Nipomo F1. In addition, Napa F1 and Kongo F1 demonstrated high tolerance. Considering all the results collectively, four genotypes, Afro F1, Kongo F1, Napa F1 and Nipomo F1, were relatively resistant/tolerant to the hawthorn-carrot aphid.
Highlights
Poland contributes 15% of the total carrot production in the EU and is the largest producer of dried carrot [1]
Field studies showed that the number of migrant alates of the hawthorn carrot aphid, as well as the colony size and percentage of colonized plants, were influenced by carrot genotype and Resistance and tolerance of carrot to the hawthorn-carrot aphid year
In the 2011 season, the hawthorn-carrot aphid was found on eight carrot cultivars (Fig 1A and 1B)
Summary
Poland contributes 15% of the total carrot production in the EU and is the largest producer of dried carrot [1]. The demand for high quality carrots, produced to the highest standards, is growing continually. These standards can be met by the application of Integrated Pest Management (IPM) principles. An important element of IPM is the cultivation of cultivars characterized by a higher degree of resistance and/or tolerance to the important pest species for the particular crop. Szwejda and Wrzodak [2] reported that due to the cultivation of carrots in Poland for decades, this plant has become a host for numerous species of harmful insects. Among the phytophagous species on carrot crops in Poland causing significant economic losses are carrot fly, Psila rosae Fabr., cutworms, Agrotis sp., and aphids.
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