Mutualismo e antagonismo floral em Daustinia montana (Moric.) Buril & A.R. Simões (Convolvulaceae)

Abstract

Convolvovulaceae species can be found in tropical and temperate regions and is represented by plants with different habits from subshrubs to herbaceous, with flowers containing five floral and reproductive appendages, showing regions with evident veins in the petals. There is a record of floral visitation in the family by a variety of insects, including Diptera, Hymenoptera, Lepdoptera and Orthoptera, in addition to high visitation by non-native bees, with emphasis on the genusApissp. There is also mention in the literature of Orthoptera under the flowers, reported as floral visitors. A single study in the Caatinga area describesdaustinia montanaas a facultative xenogam, presenting diversity of floral visitors including Coleoptera and emphasizing the importance of this species for the maintenance of local pollinators. Florivory is the process in which the florivore consumes partially or totally reproductive and/or sterile floral parts. Since flowers are the main structure of attraction for pollinators, this process can strongly influence the pattern of visits and the behavior of pollinators and negatively interfere with the production of fruits and seeds (Pre-Emergent Success) of the plant, resulting in a smaller number of seeds left for future generations. The present study aimed to analyze floral biology and the influence of florivory on pre-emergent reproductive success in daustinia montana. Considering the hypotheses: 1) The production of fruits and seeds is higher in natural pollination (control) when compared to manual self-pollination and cross-pollination; 2) There will be more fruit formation in the cross-pollination treatment; 3) Flowers with simulated florivory damage receive fewer visits than intact flowers; 4) Flowers with perforations in 50% of the corolla receive more visits than flowers with 50% of the corolla removed; 5) There is less natural production of fruits and seeds from flowers with natural florivory. The present research was carried out in a restinga environment in the Jenipabu Environmental Protection Area (“S 05º 42'034” W 035º 12' 29.4”), Rio Grande do Norte, in five populations ofd. montana. Data collection took place from September to November 2018 and May to July 2019. Experiments were conducted for: 1) analyzes of floral biology - floral size and diameter with digital caliper, Ultraviolet reflection using Ammonium Hydroxide, presence areas with glands, using neutral red, nectar production with 10μl microsyringes, stigmatic receptivity using hydrogen peroxide (70%) and anther dehiscence by direct observation; 2) determination of the type of reproductive system - natural pollination, manual self-pollination, spontaneous selfpollination, cross-pollination and apomixis; 3) observation of floral visitors - 42 hours of observation of floral visitors to flowers with presence and absence (control group) of artificial florivory with indirect damage consisting of removal of 50% of the corolla and perforations in 50% of the corolla. Finally, it was performed with artificial florivory with direct damage, counting on 36 hours of frequency observation in flowers with five stamens (control) and different numbers of stamens (three, two and none), which were removed after anthesis with the aid of of tweezers.daustinia montanashowed delayed anthesis at lower temperatures, anther dehiscence at the beginning of anthesis and nectar production throughout anthesis. In addition to 19 floral visitors, 11 hymenoptera, eight lepidopterans and one dipteran, where the lepidopterans acted by stealing nectar, with emphasis on the mothnyctelius nyctelius, abundant in frequency. The Hymenoptera Tiphiidae also stood out in frequency,Keratin(Crewella)maculifrons(Smith, 1854), Augochlora (Oxystoglossella), Dialictussp. andApis mellifera(Linnaeus, 1758). The dynamics of continuous nectar production is an interesting strategy for keeping the resource available to pollinators even if Translated from Portuguese to English - www.onlinedoctranslator.com the flower is visited by looters. Thus, the species presented a diversity of floral visitors, in addition to a reduction in visits corresponding to the increase in the extent of damage to the flower by artificial florivory. Florivory had a negative impact on the reproduction of the species, reducing the floral attractiveness and may also be related to the abortion of florivorous flowers even if they have been pollinated. There was high fruit formation by manual self-pollination (48.6%), followed by natural pollination (34.7%), spontaneous selfpollination (9%) and only 3.22% by cross-pollination.daustinia montanais self-compatible and autogamous, which is an important reproductive strategy in the absence or scarcity of pollinators, however, there was dependence on the pollination service for greater fruit formation. However, the continuous production of nectar, added to nectar plundering and florivory, may be promoting autogamy and therefore, the species runs the risk of suffering reproductive isolation in the future. The presence of non-native pollinators favors the species when natives are absent, however, beesApis mellifera, are competing with the other pollinators, evidenced by the absence of other Hymenoptera visitors during the observation period in which the bees ofApis melliferawere present in the population, therefore, possibly this species is reducing the diversity of the guild it visitsd. montana. Indaustinia montanaThe occurrence of florivory caused by Orthoptera was confirmed through direct observation in the Jenipabu Environmental Protection Area (APAJ).