Effect of wheat cultivars resistance on prey preference of Hippodamia variegata Goeze to Russian wheat aphid, Diuraphis noxia Mordvilko

Document Type : Original paper

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Abstract

Predators when offered a choice between two or more prey types, often show a preference to one of them. Therefore, prey preference of natural enemies should be considered as one of the main criteria during the study of natural enemies efficiency. This experiment was conducted to determine the feeding preference of third and fourth instar larvae and females of H. variegata to D. noxia fed on different wheat cultivars including resistant (Omid), moderately resistant (Back cross) and susceptible (Sardari) varieties. Predator preference was analyzed using the Manly’s index of preference. Results showed that life stages of predator and host plant resistance influence prey preferences, in a way that older stages of H. variegata show the preference more tangibly. Based on collected data, female of H. variegata showed the highest, intermediate and the least preference to D. noxia on Omid, Back cross and Sardari cultivars, respectively. H. variegata females killed 73.89±1.06, 67.15±1.61 and 37.18 ± 2.05 3rd instar nymphs of D. noxia during the experiment duration and preference index were 0.456 ± 0.009, 0.379 ± 0.013 and 0.165 ± 0.018, respectively. The values of this index were 0.425 ± 0.017, 0.372 ± 0.013 and 0.202 ± 0.016 for the 3rd instar larvae of ladybird. Results showed that H. variegata prefers Russian wheat aphids that feed on resistant cultivars. This tendency can be very important in developing integrated pest management programs of this species.

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