**3.3 Insect composition and diversity**

The sampled insects were identified into three orders: Hemiptera, Hymenoptera and Diptera. As shown in **Table 3**, *Aquarius remigis*, *Formica* sp. and *Chironomus* sp. were the identified species. Of these three species, only the order Hemiptera (Family: Gerridae) *Aquarius remigis* (Water strider) (adult)


#### **Table 1.**

*Mean values of physical parameters of sampled sites in Ijala-Ikeren mangrove swamp and fringes.*


**Table 2.**

*List of identified flora in Ijala-Ikeren mangrove swamp and fringes.*



*Impact of Disturbances on the Biodiversity of Ijala-Ikeren Wetland Ecosystem in Niger Delta DOI: http://dx.doi.org/10.5772/intechopen.82604*

was found in the wetland. Meanwhile, *Formica* sp. (Hymenoptera: Formicidae) were handpicked from hives hanging from mangrove plants using forceps. No significant difference was detected among insect species (F(2,14) = 1.5, P < 0.3) in their abundance. The most specious abundant was *Formica* sp. (62.6%) followed by the dipteran species; *Chironomus* sp. (24.6%) in total catch of insect individuals (171 individuals).

Spatially, the three study sites in the interior (mangrove swamp) represented the highest percentage (75.5%) of species abundance, where *Aquarius remigis* and *Formica* sp. were the only identified species there. Meanwhile, the other abundance percentage (24.5%) was recorded at the edges (fringes) in the ponds (other two sites) in relating to the abundance of one species; *Chironomus* sp.

As shown in **Table 3**, the study sites at the mangrove swamp were the richest area with species number (2 species), site 1 had the greatest value in Margalef's species richness index (d) and diversity of species out of these sites. On the other hand, site 2 had the least value of both indices.
