Forest ecosystems are of vital importance for
living organisms (Tüzün et al,
2013) so they provide habitat for a vast array of plants and animals, many of
which are still undiscovered. Three hundred million people worldwide live in
forests and 1.6 billion depend on them for hunting, gathering and medicine,
forest products such as rubber and rattan, and small-scale agriculture so their
management required considering all components of ecosystems. One important
component of forest ecosystems are insects which represent the most abundant group
in the phylum Arthropoda of the forest fauna. More than 900,000 species had
already been described and are estimated to account for more than 80 % of all
known animal species (Baker 1972) and have been around for a long time, with
fossil specimens of forest roundheaded borers having been found from 35 million
years ago (Furniss and Carolin 1977). Insects perform many roles within forests
as pollinators, herbivores, carnivores, decomposers, and food sources for other
organisms. Due to their dominant position in terms of population and the
important roles they assume, they have considerable influence in the health of
a forest ecosystem. They respond to the structural complexity of forests at different temporal
and spatial scales and are markedly influenced by natural and anthropogenic
disturbances.

Tropical forests are exposed to increasing levels of human-related
disturbances, and in the near future, the last tracts of old-growth forests are
likely to be converted into human- modified landscapes (Wright, 2005; Melo et al., 2013a). Habitat loss and
fragmentation, logging, fire and hunting, combined with regional shifts in
precipitation, have caused an alarming loss of biodiversity, collapse of key
ecosystem services and erosion of cultural heritage (Butchart et al., 2010; Laurance et al., 2012). Disturbance in an ecosystem like a forest may affect
the biodiversity of animals in different ways, according to their position in a
food chain.  In
theory at least, increased disturbance produces high species diversity in the
primary producers, intermediate diversity in herbivores and least diversity in
carnivores (Huston, 1994). For example,
forest fires have the
potential to effect significantly the insect diversity (ÖZKAZANÇ and ERTU?RUL,
2011; Costello et al.,
2011) by reducing
insect population densities directly, or by even contributing to an excessive
increase in insect populations in reducing the populations of their natural
predators. In both cases, the alteration of insect population densities poses a
threat to the health of forest ecosystems. Another case, logging residues lived
in forests may serve as a substrate for the development of certain forest bark
– and wood boring insects and in certain circumstances they can facilitate pest
multiplication and outbreaks (Schroeder, 2008) even though these logging
residues are habitats of saproxylics beetles which play an important ecologic
role in forest ecosystem. It is clear that insect organism intervene in
modulation forest ecosystem and any variation in these ecosystems influence their
diversity and composition of entomofauna and vice versa.  

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The Republic of Benin located in West Africa is characterized by a
diversity of agro-ecologic zone of which the vegetal area is progressively
degrading and it is estimated that almost 70.000ha of forest are cleared each
year (Djego et al., 2006). In its current
state, Benin’s vegetation is characterized by its parceled nature and extreme
fragmentation due not only to climatic and edaphyc conditions, which vary
rapidly according to the latitudinal gradient, but due mostly to strong anthropogenic
pressure. Benin’s flora and vegetation, especially in its Southern part, are
strongly influenced by the enigmatic Dahomey Gap phenomenon. This is translated
by a flora poor in forest and endemic plant species; it is devoid of species
typical to the dense evergreen rainforest. Flora of the main plant formations is composed of Dense semi-deciduous forests, savannas,
gallery forests and Swampy forests.

Benin presents high population growth passing from 6769 914 inhabitant to
2002 (RGPH3, 2002) to an estimate of 9. 983. 884 inhabitants (RGPH4, 2013) with
a medium rate about 3.5 % of annual increase during last decade. Likewise several factors
contribute to the degradation of vegetation: anthropogenic factors
(agriculture, exploitation of wood, crafts, medical use, vegetation fires) and
natural factors (the climate) (Sinsin & Kampmann, 2010). The pressures on the forests
include to the loss of habitats due to extensive agriculture, the destruction
of the natural environments linked to urbanization, the exploitation of wood
and the abusive collection of medicinal plants. Given these diverse activities,
man seems to be the first factor in the degradation of natural formations.

Since, classified
forests and national parks (called Protected Areas) have been established with
the goal to reduce these threats to the natural flora and the vegetation
resources. Therefore, 58 Protected Areas have been created after a long process
of which Lama Protected Forest which beneficed of an integral protection in its
central core. But over forest ecosystems such as Lokoli Swampy Forest which is
a community forest continues suffering from anthropogenic pressure on its
natural resources like medicinal plants used. 

As insects are
highly susceptible to forest disturbance, it is important and interesting to
evaluate the diversity of forest insect such as xylophagous and their natural
enemies in two kind of protected and unprotected forests.