Phenotypic diversity in the biological and behavioral responses of isolines of >i<Myzus persicae>/i< (Sulzer, 1776) (Hemiptera: Aphididae) to >i<Diaeretiella rapae>/i< (M\'Intosh, 1855) (Hymenoptera: Braconidae)

Abstract

Phenotypic diversity in the biological and behavioral responses of isolines of Myzus persicae (Sulzer, 1776) (Hemiptera: Aphididae) to Diaeretiella rapae (M'Intosh, 1855) (Hymenoptera: Braconidae) Ecological interactions are ubiquitous and occur between all macro or microorganisms. In insect-insect interactions, parasitoids are the main group of entomophagous that are exploited in biological control programs for many agricultural insect pests. Understanding the host-parasitoid interactions is essential for the development of applied research for the implementation of successful biological control programs in the field. The relationship established between host and parasitoid is the result of coevolutionary processes, in which phenotypes of parasitoids with attacking abilities were selected in response to the host's defense adaptations. In contrast, defense mechanisms developed to circumvent parasitoid attack strategies, involving behavioral and physiological adaptations were selected in the host population. The evolution of defense mechanisms developed by the host can result in biological costs, reflected, for example, in the low fertility or small size of the insect, influencing the biological aptitude of the host. To identify the phenotypic diversity in the biological and behavioral responses presented by hosts to the attack of natural enemies, we investigated the interaction between the host Myzus persicae and the parasitoid Diaeretiella rapae, using isolates of M. persicae with different responses to the attack of the parasitoid. The success of the observed parasitism of M. persicae by D. rapae ranged from 43% to 76% among 14 tested isolines. Three isolines with parasitism rate in the first (high parasitism) and fourth (low parasitism) quartiles were selected for the evaluation of biological and behavioral parameters. The biological parameters evaluated showed significant differences between lineages of M. persicae with different responses to parasitism, but without a uniform association of cost with the aphid capacity to respond to parasitism. The association of M. persicae with the secondary symbiont Rickettsia demonstrates this symbiont does not interfere directly with the aphid's ability to respond to the parasitoid D. rapae, but it had a positive effect in the fecundity of infected isolines. Rickettsia infection also influenced the defense behavior of the tested aphid isolines, with infected aphid females showing a higher frequency of body wiggling than the uninfected females. Host infection with Rickettsia also interfered in the host selection behavior of D. rapae. Parasitoid females attacked more frequently Rickettsia-free isolines. Aphids from selected isolines with low parasitism by D. rapae were also more attacked than the aphids from isolines with high parasitism. The defensive behavior displayed by wiggling the body more intensively in the group aphids with low parasitism can justify the required larger number of attacks for their successful parasitization. In Rickettsia-infected aphids we observe...