Foraging success of parasitoid wasps on flowers: interplay of insect morphology, floral architecture and searching behavior

Abstract

Intercropping with flowering herbaceous plants increases parasitoid survivorship, fecundity and retention and pest suppression in agroecosystems. Few studies, however, have examined the compatibility of parasitoid morphology and foraging ability with floral architecture. This study shows that floral architecture influences the selection of floral host resources used to provide nutrients to parasitoids in cropping systems. Parasitoid foraging performance was evaluated using real and artificial flowers which varied in degree of nectar accessibility for two eulophid parasitoids, Edovum puttleri Grissell and Pediobius foveolatus Crawford. Comparisons were made of searching performance on artificial flowers with nectars that were either scented (made from 1:1 honey-water solution) or scentless (made from 1 m sucrose solution) and differences in head widths were compared with corolla apertures. Our results showed a disparity in the ability of E. puttleri and P. foveolatus to gain access to nectar from particular types of floral architectures. E. puttleri fed efficiently only from flowers with exposed nectaries while P. foveolatus foraged efficiently from flowers having either exposed nectaries or nectaries partially obstructed by petals and stamens. Neither wasp species could forage on flowers with cup-or tube-shaped corollas because their heads are wider than the floral apertures. E. puttleri's foraging performance decreased as nectar inaccessibility increased in the artificial flowers, while P. foveolatus' foraging performance was uniform among the different artificial flowers. This indicates that E. puttleri has less propensity to search small openings for nectar than does P. foveolatus. The foraging success of both E. puttleri and P. foveolatus on artificial flowers was lower when 1 M sucrose solution was used as an artificial nectar rather than honey-water solution, indicating that the wasps were stimulated and attracted by the nectar odor. Our systematic evaluation of floral architecture with respect to parasitoid foraging ability has enabled us to predict which types of flowers would serve as suitable floral host plants for parasitoids in the field. That is, only flowers with nectaries that are completely exposed would function as suitable floral host plants for E. puttleri, while P. foveolatus could forage on flowers with either exposed or partially exposed nectaries. Examples of potentially suitable floral hosts suggested from our study include dill (Anethum graveolens L.) and fennel (Foeniculum vulgare L.) for both E. puttleri and P. foveolatus and coriander (Coriandrum sativa L.) for P. foveolatus.

Influence of flowering cover crops on Anagrus parasitoids (Hymenoptera: Mymaridae) and Erythroneura leafhoppers (Homoptera: Cicadellidae) in New York vineyards

“…It is well known that flowering plants are not equal in their suitability as food resources for different species of parasitoids (Jervis et al, 1996;Patt et al, 1997). For example, flower shape can have a large effect on accessibility of nectar.…”

“…Rows ran perpendicularly to a woodlot located on the south edge of the experimental site. Experimental units, consisting of five contiguous 80-m-long rows, were assigned to one of the following ground cover treatments: (1) sod (primarily orchardgrass, Dactylis glomerata L.), already established in the experimental site, served as a control, and was mowed when it reached 0.5 m; (2) buckwheat Fagopyrum esculentum (Moench) was seeded between rows of vines in late May of 1996 and1997;and (3) ladino clover Trifolium repens L. was planted between rows of vines in late May of 1996, and remained established through the 1997 season. Experiments were replicated four times, using a completely randomized block design.…”

Morphological characterization of pollens from three Apiaceae species and their ingestion by twelve-spotted lady beetle (Coleoptera: Coccinellidae)

“…In this way, the accessibility of entomophagous insects to these resources composes a primary factor in choosing the vegetable species that could be used to make up the crop system and optimize natural biological control (Patt et al, 1997b;Vattala et al, 2006;Barbosa et al, 2011).…”

Peran Tumbuhan Berbunga Sebagai Media Konservasi Artropoda Musuh Alami (The Role of Flowering Plants in Conserving Arthropod Natural Enemies)

“…Kebanyakan dari serangga lebih menyukai bunga yang berukuran kecil, cenderung terbuka, dengan waktu berbunga yang cukup lama yang biasanya terdapat pada bunga dari famili Compositae atau Asteraceae (Altieri et al, 2007). Misalnya, parasitoid Edovum puttleri (G) lebih menyukai bunga dengan nektar yang terlihat jelas, sedangkan Pediobius foveolatus (C) lebih tertarik pada bunga dengan nektar yang tersembunyi sebagian, walaupun keduanya merupakan parasitoid dari Leptinotarsa decemlineata (Patt et al, 1997).…”