This document summarizes a study on the biodiversity of insects associated with three fruit-bearing tree species in New Guinea forests. The study examined the composition of fruit-feeding insects on Gymnacranthera paniculata, Macaranga aleuritoides and Mastixiodendron pachyclados. A total of 184, 1938 and 289 insects were collected from the fruits of each species, respectively, representing 16, 21 and 22 insect families. The study found high insect diversity on the tree species and that total insect density decreased with increasing fruit density, supporting the Connell-Janzen hypothesis of density-dependent attack.

1. BIODIVERSITY OF INSECTS ASSOCIATED WITH FRUITS
OF Gymnacranthera paniculata WARB, Macaranga aleuritoides
MUELL AND Mastixiodendron pachyclados MELCH IN NEW
GUINEA FORESTS
By
Kari Sogera Iamba (150320132501)
Research Supervisors:
1. Dr. Ir. Danar Dono, M.Si
2. Yusup Hidayat, SP., M.Phil., Ph.D
Universitas Padjadjaran
Jatinangor
2015

2. 1.1 Background of Research
• Three fruit-bearing tree species, Gymnacranthera paniculata
(MYRISTICACEAE), Macaranga aleuritoides (EUPHORBIACEAE)
and Mastixiodendron pachyclados (RUBIACEAE) were
investigated for fruit-eating insect communities.
• These trees are predominant in Wanang Conservation Area,
used as building material for their houses, firewood for cooking
food, garden tools, for growing mushrooms (protein source of
diet) and their roots prevents soil erosion.
• There has not been a detailed study into the frugivorous insect
composition on these 3 tree species
• The findings from this study is important for formulation of
environment and conservation policies.
1. INTRODUCTION

3. 1.2 Problem Identification
• Firstly fruit-eating insect biodiversity has not been
documented in New Guinea Forests in regard to their
communities and composition on Gymnacranthera
paniculata, Macaranga aleuritoides and Mastixiodendron
pachyclados.
• Secondly, their role in maintaining high plant diversity in New
Guinea Forests has not been tested on these three woody
plants as pertaining to Connell-Janzen Hypothesis (Connell,
1971; Janzen, 1980).

4. 1.3 Research Objectives
• This study;
(i) examine the composition of fruit-feeding insects (beetles,
moths, flies, parasitoids) for three locally abundant
species, Gymnacranthera paniculata (Myristicaceae),
Macaranga aleuritoides (Euphorbiaceae) and
Mastixiodendron pachyclados (Rubiaceae)
(ii) study the response of fruit-feeding insects to different
local abundance of each tree species (i.e. testing the
Connell-Janzen Hypothesis on density-dependent attack
of fruits).

5. 1.4 Benefits of Research
• The findings will contribute to the ecology of tropical forests,
particularly the biodiversity of fruit-eating insects and
dynamics of tree species, including species important for
human usage.
• The three host tree species are beneficial to the local
communities living in the vicinity of the study area

6. 1.5 Frame Work of Research
• These trees are native and are predominant mostly in the
New Guinea lowland tropical rainforests
• Forms an important part of people’s livelihood, therefore the
roles of frugivorous insects and their roles in maintaining high
plant diversity in New Guinea Forests must be investigated for
better conservation.

7. 1.6 Hypothesis
• This study will test the following hypothesis;
(i) A high biodiversity of fruit-eating insects and their natural
enemies (parasitoids) exist on these tree species
Gymnacranthera paniculata (Myristicaceae), Macaranga
aleuritoides (Euphorbiaceae) and Mastixiodendron
pachyclados (Rubiaceae).
(ii) Fruit-eating insects act in a density-dependent manner,
increasing the percentage of attack with increasing fruit
density in the forest.

8. 2.1 Field Fruit Sampling
• Location: Wanang Conservation Area (5o13 ʹS, 145o04 ʹE, 100 m
asl), Madang, Papua New Guinea.
• Period: January to April, 2015
• Vegetation: Mixed evergreen rain forest on Latosol with a humid
climate, mean annual rainfall of 3600 mm, a mild dry season
from July to September, and mean annual temperature of 26 °C.
• Sampling method: Systemic sampling (row by row)
• Collection: Fresh fallen undamaged fruits collected on the
ground under parent trees using 2x2 m quadrat.
• Feeding guilds were based on the type of food resources
associated with fruits that the insects were feeding on and part
of fruit that insects protrude (seed and/or flesh) (Ctvrtecka et
al., 2014).
• Data: Entry in data sheet
2. METHODOLOGY

9. Materials Fruit collection Field data record
SamplesInsect rearingInsect collection
Specimen Moth mounting Data entry datasheet

10. 2.2 Laboratory Insect Sorting and Identification
• Location: New Guinea Binatang Research Center (NGBRC),
Madang, Papua New Guinea
• Period: May to June, 2015
• Aids of Identification: reference text books, online insect
databases (www.buglife.com), NGBRC insect database and
reference collections of NGBRC.
• Identification: Insect specimens were sorted initially into
morpho-species and given codes based on their distinct
morphological features. Then identified to genus and species
level.
• Data: Recored in data sheet then transfered to MS Excel to
detect density-dependent patterns of attack.

11. • Host specificity: monophagous (M) for species feeding on a
single plant species, congeneric (CG) for species feeding on > 1
congeneric species, confamilial (CF) for species feeding on > 1
confamilial genus, and allofamilial (AF) for species feeding on >
1 family (Ctvrtecka et al. 2014) .
• The infestation rates were analysed using general linear
modelling Y = b0 + b1X + ε in Minitab 17.
• Insect composition analyzed by Pearson Correlation test and
ANOVA.
• Species diversity:
• Species richness:
• Species evenness: (E) = H/Hmax
2.3 Data Analysis

12. 3. RESULTS
3.1 Diversity of Frugivorous Insects
Table 1. Gymnacranthera paniculata (Myristicaceae)
Species No. of
Individuals
P1 |In P1| (P1) |In P1|
ANIS001 (Anisopodidae) 1 0.0054348 5.214935758 0.028342042
COCCXXX (Mimemodes sp.) 1 0.0054348 5.214935758 0.028342042
DROS001 (Drosophilidae) 74 0.4021739 0.910870664 0.366328419
LONC001 (Lonchaeidae) 8 0.0434783 3.135494216 0.136325835
LYGA001 (Lygaeidae) 1 0.0054348 5.214935758 0.028342042
MYCE001 (Mycetophilidae) 1 0.0054348 5.214935758 0.028342042
NITI002 (Phenolia sp.2) 5 0.0271739 3.605497845 0.097975485
NITI003 (Cillaeus sp.) 6 0.0326087 3.423176288 0.111625314
PERIS001 (Periscelididae) 5 0.0271739 3.605497845 0.097975485
PSYC001 (Psychodidae) 20 0.1086957 2.219203484 0.24121777
SCOL164 (Coccotrypes dactyliperda) 29 0.1576087 1.847639928 0.291204119
SCOL174 (Xyleborus metacuneolus) 8 0.0434783 3.135494216 0.136325835
SCOL194 (Xyleborinus saxeseni) 2 0.0108696 4.521788577 0.049149876
TIPU001 (Tipulidae) 15 0.0815217 2.506885557 0.20436567
XXXX358 (Blastobasis sp.) 6 0.0326087 3.423176288 0.111625314
ZZZZ000 (Non-ID moth family) 2 0.0108696 4.521788577 0.049149876
Total 184 1.00 2.006637167
Spp. Diversity index: 2.006637167
Spp. Richness index: 1.179535649
Spp. Evenness index: 0.723741373

13. Table 2. Macaranga aleuritoides (Euphorbiaceae)
Species No. of
Individuals
P1 |In P1| (P1) |In P1|
AGON001 (Agonoxenidae) 2 0.001031992 6.876264612 0.007096248
ANIS001 (Anisopodidae) 1 0.000515996 7.569411792 0.003905785
BRAC001 (Braconidae) 6 0.003095975 5.777652323 0.017887468
COCC004 (Spaerosoma sp.) 49 0.025283798 3.677591494 0.092983479
CURC433 (Haplonyx sp.) 13 0.006707946 5.004462435 0.033569665
DROS001 (Drosophilidae) 147 0.075851393 2.578979206 0.195619166
FORM001 (Formicidae) 1 0.000515996 7.569411792 0.003905785
LEWAN01 (Thiotricha sp.) 6 0.003095975 5.777652323 0.017887468
LYGA001 (Lygaeidae) 1 0.000515996 7.569411792 0.003905785
MUSC001 (Muscidae) 2 0.001031992 6.876264612 0.007096248
NITI001 (Phenolia sp.1) 2 0.001031992 6.876264612 0.007096248
NITI002 (Phenolia sp.2) 1 0.000515996 7.569411792 0.003905785
NITI003 (Cillaeus sp.) 7 0.003611971 5.623501643 0.020311925
PERIS001 (Periscelididae) 332 0.17131063 1.764276824 0.302239373
PHOR001 (Phoridae) 1 0.000515996 7.569411792 0.003905785
PSYC001 (Psychodidae) 156 0.080495356 2.519555785 0.20281254
SCOL164 (Coccotrypes dactyliperda) 1112 0.57378741 0.555496318 0.318736793
SCOL174 (Xyleborus metacuneolus) 24 0.012383901 4.391357962 0.054382142
SCOL194 (Xyleborinus saxeseni) 70 0.036119711 3.32091655 0.119950546
TIPU001 (Tipulidae) 5 0.002579979 5.95997388 0.01537661
TORY001 (Torymidae) 3 0.001547988 6.470799504 0.010016717
Total 1938 1.00 1.442591566
Spp. Diversity index: 1.442591566
Spp. Richness index: 0.477026393
Spp. Evenness index: 0.473831806

14. Table 3. Mastixiodendron pachyclados (Rubiaceae)
Species No. of
Individuals
P1 |In P1| (P1) |In P1|
ANIS001 (Anisopodidae) 1 0.003460208 5.666426688 0.019607013
ANTH A1 (Araecerus sp.2) 9 0.031141869 3.469202111 0.108037436
ANTH A2 (Araecerus sp.3) 3 0.010380623 4.567814399 0.047416758
ANTH A3 (Araecerus sp.4) 1 0.003460208 5.666426688 0.019607013
ANTH A4 (Araecerus sp.5) 2 0.006920415 4.973279508 0.034417159
ANTH002 (Araecerus sp .1) 10 0.034602076 3.363841595 0.116395903
BRAC001 (Braconidae) 73 0.252595156 1.375967247 0.347562661
CURC141 (Baris sp.) 44 0.152249135 1.882237054 0.286568963
CURC321 (Conotrachelus sp.) 6 0.020761246 3.874667219 0.080442918
CURC433 (Haplonyx sp.) 1 0.003460208 5.666426688 0.019607013
DROS001 (Drosophilidae) 13 0.044982699 3.101477331 0.139512821
EUCO001 (Eucoilidae) 1 0.003460208 5.666426688 0.019607013
EULO001 (Eulophidae) 1 0.003460208 5.666426688 0.019607013
ICHN001 (Ichneumonoidea) 1 0.003460208 5.666426688 0.019607013
MUSC001 (Muscidae) 5 0.017301038 4.056988776 0.070190117
NITI002 (Phenolia sp.2) 4 0.01384083 4.280132327 0.059240586
PERIS001 (Periscelididae) 2 0.006920415 4.973279508 0.034417159
PHOR001 (Phoridae) 1 0.003460208 5.666426688 0.019607013
SCOL164 (Coccotrypes dactyliperda) 16 0.055363322 2.893837966 0.160212483
SCOL174 (Xyleborus metacuneolus) 2 0.006920415 4.973279508 0.034417159
SCOL194 (Xyleborinus saxeseni) 1 0.003460208 5.666426688 0.019607013
TIPU001 (Tipulidae) 14 0.048442907 3.027369358 0.146654571
XXXX324 (Mussidia pectinicornella) 72 0.249134948 1.389760569 0.346237927
XXXX358 (Blastobasis sp.) 1 0.003460208 5.666426688 0.019607013
ZZZZ000 (Non-ID moth family) 5 0.017301038 4.056988776 0.070190117
Total 289 1.00 2.258377854
Spp. Diversity index: 2.258377854
Spp. Richness index: 1.470588235
Spp. Evenness index: 0.701604528

15. 3.2 Density of Frugivorous Insects
654321
8
7
6
5
4
3
2
1
0
log Density of fruits
logNo.ofInsectsper1kgfruit
654321
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
log Density of Fruits
logNo.ofInsectsper1kgfruit
(a) (b)
Total Insect density (Pearson Correlation = -0.254, P-
Value < 0.001)
G. paniculata (Pearson Correlation = - 0.022,
P-Value > 0.05)

16. 3.63.43.23.02.82.62.42.22.0
8
7
6
5
4
3
2
1
0
log Density of fruits
logNo.ofInsectsper1kgfruit
65432
4.0
3.5
3.0
2.5
2.0
1.5
log Density of fruits
logNo.ofInsectsper1kgfruit
(c)
(d)
M. aleuritoides (Pearson Correlation = - 0.276,
P-Value < 0.001)
M. pachyclados (Pearson Correlation = -
0.109, P-Value > 0.05

17. 3.3 Host Specificity
Table 4. Insect Host Specificity (> 10 individuals )
Host tree Insect Morpho-species Total
abundance
Host Specificity
Gymnacranthera
paniculata
DROS001 (Drosophilidae) 74 #
Generalist
PSYC001 (Psychodidae) 20 +
Preference
TIPU001 (Tipulidae) 15 +
Preference
SCOL164 (Coccotrypes dactyliperda) 29 Generalist
Macaranga
aleuritoides
DROS001 (Drosophilidae) 148 Generalist
PERIS001 (Periscelididae) 332 *Specialist
PSYC001 (Psychodidae) 156 +
Preference
SCOL164 (Coccotrypes dactyliperda) 1112 #
Generalist
SCOL174 (Xyleborus metacuneolus) 24 *Specialist
SCOL194 (Xyleborinus saxeseni) 70 *Specialist
COCC004 (Spaerosoma sp.) 49 *Specialist
CURC433 (Haplonyx sp.) 13 *Specialist
Mastixiodendron
pachyclados
DROS001 (Drosophilidae) 13 #
Generalist
TIPU001 (Tipulidae) 14 +
Preference
SCOL164 (Coccotrypes dactyliperda) 15 #
Generalist
BRAC001 (Braconidae) 73 *Specialist
CURC141 (Baris sp.) 44 *Specialist
XXXX324 (Mussidia pectinicornella) 72 *Specialist
ANTH002 (Araecerus sp .1) 10 *Specialist

18. (a)
(b)
(c)
G. paniculata M. aleuritoides
M. pachyclados

19. 3.4 Feeding Guild of Frugivorous Insects

20. 3.5 Reared Frugivorous Insects
3.5.1 Diptera (flies) reared on G. paniculata
Figure 1. Families of Diptera; Anisopodidae (a), Drosophilidae (b), Lonchaeidae (c), Periscelididae
(d), Mycetophilidae (e), Psychodidae (f) and Tipulidae (g).

21. 3.5.2 Coleoptera (beetles) reared on G. paniculata
Figure 2. Mimemodes sp. (Cucujoidea) (a), Phenolia sp.2 (Nitidulidae) (b), Cillaeus sp. (Nitidulidae) (c),
Coccotrypes dactyliperda (d), Xyleborus metacuneolus (e), and Xyleborinus saxeseni (f).

22. 3.5.3 Lepidoptera (moths)
reared on G. paniculata
3.5.4 Diptera (flies) reared
on M. aleuritoides
Figure 3. Blastobasis sp. (Blastobasidae).
Figure 4. Phoridae (a) and Musicdae (b)
a
b

23. 3.5.5 Coleoptera (beetles) reared on M. aleuritoides
Figure 5. Phenolia sp.1 (Nitidulidae) (a), Haplonyx sp. (Curculionidae) (b), and Spaerosoma sp. (Cucujoidea) (c).
3.5.6 Lepidoptera (moths) reared on M. aleuritoides
Figure 6. Thiotricha sp. (Gelechiidae)

24. 3.5.7 Parasitoid: Hymenoptera (wasps) on M. aleuritoides
Figure 7. Braconid wasp
3.5.8 Coleoptera (beetles) reared on M. pachyclados
Figure 8. Baris sp. (Curculionidae) (a) and Conotrachelus sp. (Curculionidae)
a b

25. a b
c
d
e
Figure 9. Araecerus Sp.1 (a), Araecerus Sp.2 (b), Araecerus Sp.3 (c), Araecerus Sp.4 (d), and Araecerus Sp.5 (e).

26. 3.5.9 Lepidoptera (moths) reared on M. pachyclados
Figure 10. Mussidia pectinicornella (Pyralidae)

27. 4. DISCUSSION
4.1 Diversity of Frugivorous Insect Species
• Each of the three host trees had different fruit-eating insect
diversity (H,) species richness (D) and species evenness (E).
• The insect diversity associated with fruits was highest in M.
pachyclados since it possess larger seed size than other two
plant species and has soft endocarp (seed) for ease of
penetration by frugivorous insect larvae.
• G. paniculata (H= 2.007) with second highest insect diversity was
attributed to its soft mesocarp and semi-soft endocarp (seed)
that permits penetration by insect larvae.
• M. aleuritoides (H= 1.443) was least diverse probably due to its
seeds being shielded with chemical defences and mechanical
defences of mesocarp.

28. 4.2 Density of Frugivorous Insects
• Density of insects (number of insects per 1 kg fruits) generally
decreases with increasing fruit density.
• Decreasing trend might be due to herbivore satiation (Burkey,
1994; Forget et al. 1999; Kelly et al. 2000).
• Supported by low seed infestation of true seed feeders like
Scolytinae , Curculionidae, Anthribidae, Pyralidae, Blastobasidae,
Gelechiidae and Agonoxenidae.
• Another factor in decrease of insect density maybe Host-
parasitoid relationships since parasitoids may contribute to the
decline of host frugivorous insects thus leading to lower insect
densities.

29. y = 5.068 – 0.7319x
y = 4.024 – 0.677x
Figure 11. Positive correlation between host and
parasitoid on Macaranga aleuritoides and statistically
significant (Pearson r = -0.443, P < 0.05).
y = 2.276 – 0.06012x
y = 3.449 – 0.3807x
Figure 12. Positive correlation between host and
parasitoid on Mastixiodendron pachyclados and
statistically significant (Pearson r = -0.222, P < 0.05).

30. 4.3 Host Specificity of Frugivorous Insects
• Monophagy was found to be rarer in frugivorous beetles in New
Guinea forest.
• Species of Drosophilidae reproduce on a wide range of resources
such as fruits, sap, flowers, mushrooms and cacti where host
chemistry may pose great challenges for Drosophila species .
• Psycodidae, Mycetophilidae, Periscelididae and Tipulidae are
considered as decomposers and recyclers of decaying materials
such as rotting logs, fruits and othe decaying matter .
• Coccotrypes dactyliperda (Scolytinae) was considered generalist
• Varying abundances on each woody plant may be due to host
plant chemistry, morphology and food resources they offered

31. 4.4 Feeding Guild of Frugivorous Insects
• Feeding guilds were based on the food resources provided or
associated with fruits and part of fruit fed on.
• Seeds are often shielded with chemical and mechanical defences
• Specialists such as seed predators which possess detoxifying
mechanisms attack seeds which are mainly chemically protected
• Mesocarp is thought to be less chemically defended than seeds
• Specialists who will often be in low numbers than the mesocarp
feeders.
• Drosophilidae is both frugivore and scavenger.
• Tephritid flies were not reared mainly due to very thin fruit mesocarp.
• Nitidulidae (Phenolia & Cillaeus sp.) are considered both scavengers
and as fungal-feeders (mycetophagous)
• Feeding guilds varied according to resources insect prefer as provided
by fruits either for their reproduction, food resources or both.

32. 5. Conclusion
• The biodiversity of fruit-eating insects in New Guinea Forests
and their roles in maintaining high plant diversity in tropical
forests is important.
• Communities of frugivorous insects feed on fruits of tropical
forest trees and their host specificity and unique feeding
guilds plays a very important role in the plant’s distribution.
• Other factors such as host-parasitoid relationships, herbivore
satiation, distance-density fruit patterns and competition
among frugivorous insects may have contrasting effect on the
Janzen-Connell hypothesis.
• Contributes to better understanding of the ecology of tropical
forests, particularly the dynamics of tree species, and
potential role of frugivorous insects in it.

33. End of Presentation
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