Host Attraction and Selection in the Swede Midge (Contarinia nasturtii)

Abstract

Gall midges (Diptera: Cecidomyiidae) are a speciose family that, as adults, are short lived (lasting only a few days), they use olfactory cues for host and mate localization, and their host plant specificity is a key characteristic of the family. These traits make them good models with which to study the role of olfaction in speciation. The overall objective of this study was to analyze the host selection behavior of the gall midge, Contarinia nasturtii, a crucifer specialist that also is a crucifer pest. Here, we demonstrate that the host specificity of gravid C. nasturtii females was initiated by the olfactory-driven host plant choice during oviposition. Olfactory preference of the female, while narrow, encompassed more plants than were accepted for egg-laying, indicating that other factors following the initial olfactory attraction are involved in ultimate host choice. Similarly, C. nasturtii showed flexibility in host plant choice depending on which plants were available for oviposition. Larvae developed on host plants selected by females for oviposition. This slightly broader range of olfactory preference over acceptance, and the flexibility in host choice, might be the basis for the rapid speciation reported in the gall midge family. Furthermore, we assessed whether ubiquitous and/or family-specific plant odors are involved in the attraction of gravid C. nasturtii to their hosts. For that, we used the crucifer Arabidopsis thaliana, which has a broad range of defined ecotypes and large number of mutants. The attraction of C. nasturtii to two A. thaliana-types were tested; one that does not produce the ubiquitous green leaf volatiles (Columbia, Col-0), and a knock-out mutant which does not produce the crucifer-specific glucosinolates. Surprisingly, C. nasturtii was attracted to both types, indicating that neither of these compounds, nor their breakdown products (e.g., isothiocyanates), are essential for C. nasturtii host attraction.

Swede midge (Diptera: Cecidomyiidae) diapause initiation under stable conditions: not a family affair

“…Some non-genetic factors could potentially influence variation in diapause initiation under a stable environment and thus warrant consideration. For example, because swede midges lay multiple clutches on the preferred Brassica hosts (Boddum et al 2018), a shortage of optimal oviposition sites could result in nutritional or growth rate differences among siblings developing on different regions of the host plant. These differences could, in turn, influence the propensity to Fig.…”

Efeito do estresse hídrico na composição química de brássicas e sua influência em Plutella xylostella (L., 1758) (Lep.: Plutellidae) e Trichogramma pretiosum Riley, 1879 (Hym.: Trichogrammatidae)

“…O alpha pinene foi utilizado em estudo recente com díptera Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae), um inseto especialista "galhador" em brássica, como sinal químico de localização da planta hospedeira (BODDUM et al, 2018).…”

“…De modo geral, esses dois tipos de compostos abrangem a maior parte de compostos voláteis verdes emitidos pelas brássicas (couve, brócolis e repolho), com seus respectivos tratamentos. Dos compostos da classe terpenoides, apenas dois tipos foram emitidos pelas plantas das três variedades, sendo eles os monoterpenos, com uma grande variedade de compostos, e os sesquiterpenos, com apenas dois compostos, tendo eles a função de sinal químico de localização da planta hospedeira (BODDUM et al, 2018).…”