**2. Land use and insects dynamics**

Land use is the conversion of natural environment to a built environment and this is majorly caused by human activities [6]. Natural rainforests are one of the most species-rich and functionally important terrestrial ecosystems [7]. Tropical forests are the most bio-diverse terrestrial habitat, with 50% of the world's species [8, 9], but about 68,000 km2 of tropical forest is lost annually [6], an amount that could be increasing by 3% (2000 km2 ) each year [10], remains 11 million km<sup>2</sup> , virtually half (5 million km2) is considered to be either deforested area [11] or degraded forest that has to regenerate after human use (e.g., cropped land abandonment and clearfelling: [12, 13] or natural disturbances (e.g., fires and windstorm) [14]. Insects are essential components in most natural and transformed landscapes. They play crucial functional roles that ensure the delivery of various ecosystem services necessary for several aspects of human livelihoods, such as agriculture, tourism, and natural resource use [2, 15, 16]. They also control populations of other organisms and provide a significant food source for other taxa [17]. However, they are also disease vectors to many other organisms, including humans, and they can alter the rates and directions of energy and matter fluxes in an ecosystem [18]. Recent reports imply devastating declines in the decline of all levels of biodiversity with potentially dire implications on ecosystem functioning [19, 20].

The tropical forest with high species composition, and high level of biodiversity is currently faced with a lot of challenges when it comes to its conservation [21]. Natural forests have been reported to contain a high diversity of insect and trees species diversity than other land-use types and this has been attributed to the high level of relationship between the various components of the forest ecosystem [22]. According to [23], conversion of forest to other land use types is one of greatest threats to insects, causing population declines and shifts in community composition. The tropical forests have been subjected to extensive disturbance by logging and clearance for agriculture; especially palm oil, cocoa, pasture, and rubber plantation [24, 25]. OT et al. [26] reported that tree species, which is a significant component of forest ecosystem plays vital roles in forest biodiversity conservation. Conversion of this forest to other land use type will affect the population and result to loss of key stone species that are very important to the forest ecosystem balance. Land-use change, particularly the conversion of natural forest to agriculture to sustain the growing global population, has negative effect on biodiversity conservation and contributes to climate change.

## **3. Contributions of insects to human nutrition**

The decline in insect biodiversity concurrently presents an immediate threat to food security [17] and permanently affects humans' health and wealth. All terrestrial insects provide resources for higher trophic levels, especially for many vertebrates [18]. Then, the vertebrates and other beneficiaries in the trophic groups are subject to humans. It is expected that by 2050 the projected world population will be 9.8 billion and 11.2 billion by 2100 [27]. In particular, pollinating insects

*Land Use Impacts on Diversity and Abundance of Insect Species DOI: http://dx.doi.org/10.5772/intechopen.106434*

have experienced significant declines for several decades in many parts around the world [28]. This is a serious concern because pollination represents a critical ecosystem service [29], and declines in pollinators have been directly linked with reductions in the plants with which they interact [30]. Though, the pollination services of honeybees are just as valuable as their production of honey and wax which are useful humans. Meanwhile, plants serve several purposes in human existence on Earth. This is of particular importance because most insects interact with plants, and an estimated 85% of angiosperms, including most tropical tree species, are directly pollinated by insects [31]. Most insect species are associated with living plants [32] and are highly specialized in food resources and microhabitats [33].

#### **3.1 Major edible insects**

Insect are rich protein source. Practically 100 analyzed edible insects at egg, larva, pupa or adult stages and the raw protein content is generally 20–70% [34, 35]. Globally, Most commonly consumed insect orders are beetles (Coleoptera), caterpillars (Lepidoptera), Bees, wasps, ants (Hymenoptera), grasshoppers, locusts and crickets (Orthoptera), cicadas, leafhoppers, planthoppers, scale insects, true bugs (Hemiptera), termites (Isoptera), dragonflies (Odonata), flies (Diptera). Consumption of these insects differs to each region of the world depends on stages of insects. Lepidoptera are consumed completely as caterpillars and Hymenoptera are consumed regularly in their larval or pupal stages [36]. Both adults and larvae of the Coleoptera order are eaten, while the Orthoptera, Homoptera, Isoptera and Hemiptera orders are mostly eaten in the mature stage [37]. Besides serving as sources of food, insects provide humans with a variety of other valuable products. Honey and silk are the most commonly known insect products. Bees produce about 1.2 million tonnes of commercial honey per year [38, 39], while silkworms produce more than 90 000 tonnes of silk [40].

## **4. Impact of land use on insects population**

The conversion of Natural forest ecosystem has led to decline in the population of insect species. Many factors such as land-use changes, deforestation, pollution, urbanization, intensive agriculture, among others have been reported to contribute to this decline. The activities of humans in natural ecosystems have lead to habitat fragmentation, isolated from each other by prevailing conditions of hostile lands created by human activities [41]. This fragmentation leads to smaller habitat areas and decreased biodiversity [42]. As a result of changes, species are threatened and vulnerable to extinction. Loss of key stone insect species has also affected the population of other species and other components of the forest ecosystem, and it's because of the level of inter-dependency between these insect species and the natural forest ecosystem. Such losses lead to the reduction in ecosystem goods and services which human depend on for their survival (**Table 1**).

#### **4.1 Urbanization**

Urbanization is increasing in most developed and developing nations of the world, which leads to habitat fragmentation and converting the significant habitats of insect species into smaller areas and converting the forest into agricultural areas

#### *Vegetation Dynamics, Changing Ecosystems and Human Responsibility*


*Source; Adeduntan et al., 2021.*

*NF; Natural forest, RP; Rubber plantation, OP; Oil palm plantation.*

#### **Table 1.**

*Abundance of insect composition in each ecosystem in Okomu Edo state Nigeria.*

and communities [43]. In tropical West Africa, a considerable decline in some insect populations was observed due to Urbanization [43, 44]. Globally, vegetation has been converted into an urbanization setting to bridge the craving for urban population increase, which alters the habitat of insect species and leads to insect decline except in bees keeping [43, 45] in the most fragment of the forest habitats today. Then, insect crossing on the roads during construction, collusion of insects with vehicles, and death of soil-borne insects during road constructions [46] are not major factors that decrease insect species in the forest habitat.
