Asif Sajjad

Pollen Deposition Is More Important than Species Richness for Seed Set in Luffa Gourd

In the context of global biodiversity decline, it is imperative to understand the different aspects of bee communities for sustaining the vital ecosystem service of pollination. Bee species can be assigned to functional groups (average difference among species in functionally related traits) on the basis of complementarity (trait variations exhibited by individual organisms) in their behavior but is not yet known which functional group trait is most important for seed set. In this study, first, the functional groups of bees were made based on their five selected traits (pollen deposition, visitation rate, stay time, visiting time of the day, body size) and then related to the seed set of obligate cross-pollinated Luffa gourd (Luffa aegyptiaca). We found that bee diversity and abundance differed significantly among the studied plots, but only the bee species richness was positively related to the seed set. Functional group diversity in terms of pollen deposition explained even more of the variance in seed set (r2 = 0.74) than did the species richness (r2 = 0.53) making it the most important trait of bee species for predicting the crop reproductive success.

Insect pollinator diversity in four forested ecosystems of southern Punjab, Pakistan

This study investigated pollinator assemblage diversity and richness in four forested ecosystems of southern Punjab, Pakistan, with different landscape types. Pirowal is situated in the plains of irrigated Punjab, Lal Suhanra is part of a sandy desert ecosystem, Ghazi Ghat is part of the Indus River delta, and Fort Munro is located in dry hilly mountains. A yearlong survey of pollinator populations was carried out in these four forested ecosystems from January to December of 2010. Fortnightly hand netting was performed for collecting flower-visiting insects whereas, pan traps of three colors (white, blue, and yellow) were deployed for collecting the data. A total of 8,812 individuals from two orders (Lepidoptera and Diptera) were observed, including 22 families and 154 species. Bees were the most abundant, with 4,502 individuals, and the most species-rich taxa, with 70 species in five families, followed by flies having 2,509 individuals and 51species in 10 families. Wasps were the least abundant with 1,801 individuals and 33 species in seven families. The assemblage structure of pollinator communities as visualized through rank abundance curves showed that there were many species with low abundance and only a few species with a much higher abundance. The most abundant species among the bees, in order, were Nomia sp.3, Megachile bicolor, and Colletes sp.3; among flies, Syrphus sp.2, Calliphoridae sp.1, and Empididae sp.4; and among wasps, Tiphiidae sp.1, Myzininae sp.2, and Scelionidae sp.1.

Effect of temporal data aggregation on the perceived structure of a quantitative plant–floral visitor network

Seasonal turnover in plant and floral visitor communities changes the structure of the network of interactions they are involved in. Despite the dynamic nature of plant–visitor networks, a usual procedure is to pool year‐round interaction data into a single network which may result in a biased depiction of the real structure of the interaction network. The annual temporal dynamics and the effect of merging monthly data have previously been described for qualitative data (i.e. describing the occurrence of interactions) alone, while its quantitative aspect (i.e. the actual frequency with which interactions occur) remain little explored. For this, we built a set of 12 monthly networks describing year‐round plant–floral visitor interactions in a 30‐hectare planted forest and its adjacent agricultural landscape at Bahauddin Zakariya University Multan, Pakistan. A total of 80 plant and 162 insect species, which engaged in 1573 unique interactions, were recorded. Most network properties (particularly the number of plants, visitors and unique interactions) varied markedly during the year. Data aggregation showed that while animal species, plant species, unique interaction, weighted nestedness, interaction diversity and robustness increased, connectance and specialization decreased. The only metric which seemed relatively unaffected by data pooling was interaction evenness. In general, quantitative metrics were relatively less affected by temporal data aggregation than qualitative ones. Avoiding data aggregation not only gives a more realistic depiction of the dynamic nature of plant–visitor community networks, but also avoids biasing network metrics and, consequently, their expected response to disturbances such as the loss of species.

Yearlong association of insect pollinator, Pseudapis oxybeloides with flowering plants: Planted forest vs. agricultural landscape

The yearlong association of a native bee, Pseudapis oxybeloides (Halictidae: Hymenoptera) was studied with 72 plant species in a sub-tropical planted forest and some adjacent agricultural landscapes at Multan, Pakistan. The study resulted in 66 interactions of P. oxybeloides with only 24 plant species in 15 families while other 48 plant species were not visited by this bee. The maximum abundance of P. oxybeloides (7–9 individuals) was recorded on Achyranthes aspera and Launaea procumbens followed by Ageratum conyzoides, Trianthema portulacastrum and Cleome viscosa (5–6 individuals). Majority (19) of plant species were visited by only 1–4 individuals. The bee activity was started in the month of March which attained its peak in May followed by a gradual decline until September. No bees were observed during the months of January and February. There was a significant positive relationship between bee abundance and number of flowering plant species. Bee abundance had a strong positive relationship with temperature while it had a strong negative relationship with relative humidity (%). Floral abundance increased with the number of flowering plant species while it was not influenced by floral span of plant species. Besides giving the floral host plants of P. oxybeloides, the current study also gives a better understanding of its seasonality along with its relationships with different biotic and abiotic factors under local conditions. These findings can help in maintaining and managing P. oxybeloides population particularly and other native bees in general at local scale.

Assemblage of pollinator communities in four widely isolated nature reserves of southern Punjab, Pakistan

Pollinators are key components of the global biodiversity, providing vital ecosystem services of pollination to crops and wild plants. Understanding pollinator assemblage and how it changes spatially is important in order to device effective ecosystem management planning. This is the first empirical study to explore pollinator community structure in four widely isolated nature reserves of southern Punjab, Pakistan, i.e., the central agricultural plain (Pirowal Forest), the Indus delta plain (Ghazi Ghat Wetland), hilly mountains (Fort Munro), and a sandy desert (Lal Suhanra Forest). Six assemblage parameters, i.e., abundance, richness, dominance, evenness, Simpson index, and Shannon-Wiener index, were studied over seven consecutive months (February to August 2012). Maximum abundance and richness of the pollinators were recorded at Ghazi Ghat (1354 individuals and 84 species), followed by Pirowal (1331 individuals and 80 species), Lal Suhanra (1197 individuals and 77 species), and Fort Munro (808 individuals and 65 species). The highest values of Simpson and evenness indexes were recorded at Fort Munro, while the Shannon-Wiener and dominance indexes were highest at Ghazi Ghat and Pirowal. Species richness was highest for bees, while it was lowest for flies, yet the latter were the highest in abundance among the four pollinator groups. The current study is a first account of pollinator assemblage structure in four widely isolated forest reserves of Punjab, Pakistan. This will support ecosystem management planning, and opens doors for further research in order to reveal complexities in pollinator assemblage structure especially in relation with plant communities.