Helianthus annuus pollen, an oviposition stimulant for the sunflower moth, Homoeosoma electellum

Abstract

Females of the sunflower moth, Homoeosoma electellum, laid a total of 242.3 + 27.4 (X +_ SE) eggs when provided oviposition sites of wax paper dusted with pollen from cultivated sunflowers. Fecundity was influenced by the age at which mating occurred but not by the duration of mating. Eggs were laid during both the light and dark portions of a 16L:8D photoperiodic cycle, with an evident peak occurring shortly after the onset of the scotophase.The fecundity of females provided oviposition sites with a 1 mg equivalent of an ethanolic pollen extract daily (124.2 + 22.8) did not differ significantly from that of females provided 1 mg of pollen (172.2 + 28.0). Furthermore, the females showed the same positive dose dependent oviposition response where sites contained different concentrations of either pollen or pollen extract. However, when different oviposition substrates were provided simultaneously, females preferred pollen > 'reconstituted pollen' (extract + pollen residue following extraction) = pollen extract > pollen residue = wax paper control. These data confirm the presence of an oviposition stimulant for 14. electellum in the sunflower pollen.Antennectomised females laid as many eggs on sites with pollen residue as on sites with pollen, indicating that the majority of sensillae for detecting the oviposition stimulant are located on the antennae.The importance of pollen load as an indicator of a suitable host plant, given that previous laid eggs do not inhibit subsequent oviposition, is discussed with respect to larval survival.

Crop domestication disrupts a native tritrophic interaction associated with the sunflower, Helianthus annuus (Asterales: Asteraceae)

“…First, H. electellum oviposition occurs when flowers are in anthesis; 84-90% of the eggs on the flower are laid in the first 7 days of flowering, because the presence of pollen stimulates oviposition (Depew, 1983;Delisle et al, 1989). Although flower size was not linearly related with larval abundance, larval abundance was the highest on the largest flowers.…”

Do pollen beetles need pollen? The effect of pollen on oviposition, survival, and development of a flower‐feeding herbivore

“…Pollen cues may also be detected, and similarly act as oviposition stimulants, such as those reported from sunflower pollen that are active on sunflower moths Homoeosoma spp. (Delisle et al ., 1989; Le Métayer et al ., 1993).…”

“…Larvae of different pollen‐feeding species vary in their pollen‐host specificity. For example, phytoseiid mite Euseius finlandicus Oudemans larvae can feed and develop on a number of different pollens (Broufas & Koveos, 2000), but larvae of the sunflower moth Homoeosoma electellum (Hulst) develop only on sunflower Helianthus annuus (L.) or related pollen (see Delisle et al ., 1989). Whether or not specialisation reflects an absolute requirement of the larvae for the pollen of a particular host species or the effect of female's oviposition or feeding preferences (Bernays & Graham, 1988; Thompson, 1988; Scheirs et al ., 2000) is often difficult to determine; however, female oviposition prefer‐ences usually (but not always) relate well to larval perform‐ance (reviewed in Leather, 1994).…”

Behavioral consequences of innate preferences and olfactory learning in hawkmoth–flower interactions

“…Floral signals acting in such a manner have been found in females of the host-specialist senita (Upiga virescens) (35) and yucca moths (Tegeticula and Parategeticula spp.) (36,37) and the facultative specialist sunflower moth (Homoeosoma electellum) (38). For M. sexta females, field observations and laboratory experiments suggest that host-plant flowers may play a similar role (39,40).…”