Antherina suraka (Lepidoptera: Saturniidae): ecology, systematics, and potential economic uses to promote conservation in Madagascar

Randrianandrasana, Maminirina

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Description

Title

Antherina suraka (Lepidoptera: Saturniidae): ecology, systematics, and potential economic uses to promote conservation in Madagascar

Author(s)

Randrianandrasana, Maminirina

Issue Date

2015-01-21

Director of Research (if dissertation) or Advisor (if thesis)

Berenbaum, May R.

Doctoral Committee Chair(s)

Berenbaum, May R.

Committee Member(s)

• Alleyne, Marianne
• Berlocher, Stewart H.
• Hanks, Lawrence M.
• Whitfield, James B.

Department of Study

Entomology

Discipline

Entomology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Antherina suraka
• Saturniidae
• Lepidoptera
• Arthropods
• wild silkworm
• host plants
• biogeography
• DNA-barcoding
• cocoon
• tensile strength
• modulus
• silk
• thread
• thickness
• sheet
• amino-acid
• fibroin
• entomophagy
• insect
• Malagasy
• food security
• Madagascar
• Comoros
• biodiversity
• deforestation
• conservation

Abstract

Wild silk production provides an ecologically compatible alternative to forest destruction and invests the rural communities in conserving their natural heritage. This study permitted acquisition of data on various biological aspects to allow local communities to harvest the silk of the Malagasy endemic saturniid silkworm Antherina suraka (Boisduval, 1833) as a source of ecologically sustainable income. The current study provided information to local farmers about the available host plants optimal for rearing the local silkworm and therefore worth conserving. Documentation and field surveys were undertaken from 2008 to 2011 in different regions of Madagascar. Food plant species from 23 families were recorded. The discovery of ten newly recorded host plant species endemic to Madagascar showed that, although A. suraka has adapted to feed on non-native species, it remains reliant on native forests. Host availability in different study sites was documented. Despite the efforts undertaken during this study, fewer records of host plants were found in the dry areas, in contrast with other regions of Madagascar. Further studies of A.suraka in these special ecosystems along the year were then suggested. About A.suraka itself, three forms currently recognized as the subspecies suraka, australis and comorana differ in geographical distribution, body size and color. The taxonomic status of these subspecies was assessed. Records from museums and field investigation (2007-2012) showed that A. suraka is widely distributed in all bioclimatic zones of Madagascar and the Comoros archipelago. The Folmer region of mitochondrial cytochrome oxidase I was used to test for differences among geographic samples. Three clades comprising the three subspecies were supported. As only 43 specimens in limited regions were analyzed, further studies are needed to understand geographic variation in A. suraka. Results of Mantel and partial Mantel tests on ten samples with known host plants showed correlations between genetic and geographical distance. Isolation by distance could explain the observed phylogenetic structure. Structural and mechanical properties of the cocoon of A.suraka were also assessed. Using environmental scanning electron microscopy, I found that the cocoon was characterized by multiple threads with crossover points. Use of a tensile strength testing instrument revealed that its silk sheet is less compact, with lower tensile strength and stiffness but greater thickness than that of B. mori. No major differences in either structural or mechanical properties were observed between two sites, Kirindy and Isalo. Comparison between the two layers forming the cocoon showed that the inner layer had greater tensile strength, elastic modulus and thread and cell density but was thinner, with larger cell and thread. These results indicated that the cocoon of A. suraka, although strong enough for making a non-woven fabric, was less strong than that of B. mori. Because the pupae of A. suraka are edible, eating or selling them could improve local economies. Entomophagy is not new in Madagascar where insects have long been part of culinary traditions. Promoting this practice would help in enhancing food security as insects are nutritious and affordable for a large segment of the population. We conducted a survey in rural communities of Madagascar from April to June 2013. Diversity of edible non-crustacean arthropods was assessed for each site using the number of times names of arthropods consumed were mentioned as a measure of acceptability. Approximately 65 morpho-species from seven orders of insects, including Hemiptera, Coleoptera, Lepidoptera, Orthoptera, Hymenoptera, Odonata and Mantodea, and two orders of arachnids, including Araneae and Ixodida, were recorded as the most frequently consumed arthropods. Preference rankings differed among sites. Information on seasonal availability was also recorded from the informants. When comparing factors influencing food security in rural areas, we noticed that most of the edible species were found between October and March, a time associated with the lean season and hikes in food prices. This pattern demonstrates the importance of entomophagy in food security. Rearing selected edible and/or silk-producing insects at a marketable level would further improve livelihoods, thus protecting the remaining forests in Madagascar from overexploitation.

Graduation Semester

2014-12

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http://hdl.handle.net/2142/72781

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Copyright 2014 Maminirina Randrianandrasana

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