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Study of floral visitation on Leea asiatica

Citation

khache, omkar (2021), Study of floral visitation on Leea asiatica, Dryad, Dataset, https://doi.org/10.5061/dryad.np5hqbzsh

Abstract

Leea asiatica (L.) Ridsdale is a common understory shrub in lowland moist deciduous forests of Western Ghats. It is visited by a variety of insects, which makes it interesting to study visitation dynamics and diversity. The objective is to get an overall view of this system and find gross trends.

The work was carried out in a semi urban locality, near Aarey forest, in Mumbai, India. The field work lasted over a total of 13 days in August 2020. Data was sampled through video recordings of visitor activity on a single inflorescence every day. Visitor activity was recorded from 8am to 2pm, every 30mins. For visitation rate, the number of visits to the inflorescence and in the inflorescence, visitor identity, and time of entry and exit (for time spent on the inflorescence) were noted. For looking at visitation dynamics Apis florea was used as the candidate species because it was the most frequent visitor.

Frequent visitors on Leea asiatica, were Apis florea, Braunsapis sp, members of Calliphoridae and Ceratina sp, in respective order. A total of 26 species visited L.asiatica over 13 days. The Simpsons diversity index (D) is 0.3.

Mean visitation rate is 0.7±0.46 visits/inflorescence/min and 0.6 ±0.37 visits/flower/min. Overall number of visits and visitation rate dropped from 8am in the morning to 2pm in the afternoon. Handling time gradually increased till 1pm and started to drop. The trends are not always very strong as these are gross estimations and other variables were not controlled for.

Methods

Study species

Leea is a genus from the grape family Vitaceae which occurs throughout the old world tropics, from Africa to Asia, north eastern Australia, Islands of the pacific, but has diversified the most in Indomalayan region (J. E. Molina et al., 2013), with as many as 29 species in India Clarke (1881 as cited in (J. E. Molina et al., 2013).  Leea asiatica, the plant in this study grows up to 8m tall, and has greenish-white pentamerous flowers with a presence of 3-4mm long floral tube (Ridsdale C. E. 1974). The flowers are in conspicuous moderate to large corymbs, and are frequented by a variety of insects. L. asiatica is a generalist when it comes to visits by insects. (J. Molina, 2009) reporting up to 21 species on Leea sps, from over 4 orders of Insects. Leea asiatica blooms from July end to mid-September. The field work was done during August due to heavy rain in July.

Study area

 The field work was conducted near Aarey Guesthouse (19.142910°; 72.881846°), from 2nd August 2020 to 26th August 2020. Aarey forest is a part of the eco-sensitive zone of Sanjay Gandhi National Park, Mumbai. The forest is of mixed deciduous type, interspersed with disturbed landscapes and man-made grasslands. In the sampling area the forest was a mixture of mixed deciduous and some planted species. Aarey forest was chosen as the area to conduct the study because of its convenience during the COVID restrictions and the National parks were closed.

Observational methods

Plants, 1m on either side of a 100m path were chosen based on their flowering status (Figure 1). From a total of 81 plants along the road data was collected from 13 of them. One plant per day was chosen for data collection, therefore there were 13 observation days.

Visitor activity on the plants was collected by means of video recording (Figure 2). Data was collected on 13 days from Aug 2nd to Aug 26th 2020 (the bloom ended by this time). There were several days data couldn’t be because of heavy rain. The camera (Canon DSLR with 55 lens, Tripod), was focused on an inflorescence and recording was done from 8am to 2pm. Every hour of the observation period is represented by 30mins, therefore a total of 180mins of data was recorded for 6 hours every day. The data was recorded through-out light rain, but stopped when it rained heavily

Usage Notes

The files arranged date wise are raw data for observational days.