Macrozamia

Abstract: Cone traits (volatile components and thermogenesis) of three cycad species in the genus Macrozamia were examined for differences related to their specific insect pollinators, the weevil, Tranes spp., or the thrips, Cycadothrips chadwicki. Linalool (>80% of emissions) dominated cone volatile components of M. machinii (Tranes-pollinated) and beta-myrcene was a minor component (<9% of emissions). Volatiles of M. lucida and M. macleayi cones (Cycadothrips-pollinated) were dominated by beta-myrcene (up to 97% of emissions), but no linalool was detected. Pollinator movement into and out of cones coincided with cone thermogenesis and peak odor emission: around sunset for Tranes, and at mid-day for Cycadothrips. Female cone traits were similar to those of their conspecific male cones. Differences in cone traits between Macrozamia species may thus be responsible for conferring pollinator specificity in areas of sympatry.

Abstract: Specialist beetles (Insecta, Coleoptera) have generally been considered to be the sole pollinators of cycads that have been studied. The possible pollination role of members of the thrips genus Cycadothrips (Thysanoptera, Aeolothripidae) found on male and female cones of some species of the Australian cycad genus Macrozamia (Zamiaceae), however, has never been experimentally investigated. This study, which included behavioral observations, visitation rates, pollen loads and exclusion experiments of insect visitors to Macrozamia communis cones in New South Wales, indicated that both Cycadothrips chadwicki Mound and Tranes lyterioides (Pascoe) (Coleoptera, Curculionidae) affect pollination. This is the first demonstration that specialist pollinators of two different insect orders pollinate a cycad. Cycadothrips adults and larvae fed on pollen, and Tranes weevil adults fed mainly on male sporophyll tissue and some pollen. Larvae of both insects developed in male cones; thrips larvae fed on pollen and weevil ...

Abstract: Macrozamia macdonnellii (Zamiaceae) grows at a few isolated sites in central Australia. Male cones support large populations of a host‐specific thrips, Cycadothrips albrechti n.sp. (Thysanoptera, Aeolothripidae). This insect breeds only in these male cones, from which the adults swarm in late afternoon as the temperature falls and humidity rises. A small sticky trap at one female cone caught 3844 adults on a single afternoon; large numbers of thrips were observed entering this cone. Each thrips carried an average of 15 pollen grains, and pollen delivery into the cone was thus estimated to average more than 5500 grains per ovule. No other potential pollinators were found on these cycads, and it is concluded that C. albrechti is the sole pollinator of M. macdonnellii. Since Cycadothrips constitutes a basal clade within the Thysanoptera, the possibility is considered that thrips were involved in pollen transfer before the radiation of flowering plants.