Abstract
Since the advent and widespread use of high-resolution molecular markers in the late 1970s, it is now well established that natural populations of insects are not necessarily homogeneous genetically and show variations at different spatial scales due to a variety of reasons, including hybridization/introgression events. In a similar vein, populations of insects are not necessarily homogenous in time, either over the course of seasons or even within a single season. This of course has profound consequences for surveys examining, for whatever reason/s, the temporal population patterns of insects, especially flying insects as mostly discussed here. In the present article, the topics covered include climate and climate change; changes in ecological niches due to changes in available hosts, i.e., essentially, adaptation events; hybridization influencing behaviour–host shifts; infection by pathogens and parasites/parasitoids; habituation to light, sound and pheromone lures; chromosomal/genetic changes affecting physiology and behaviour; and insecticide resistance. If such phenomena—i.e., aspects and pitfalls—are not considered during spatio-temporal study programmes, which is even more true in the light of the recent discovery of morphologically similar/identical cryptic species, then the conclusions drawn in terms of the efforts to combat pest insects or conserve rare and endangered species may be in error and hence end in failure.
Highlights
In the present article, I briefly relate how aspects of the temporal sampling of flying insects (Subphylum Hexapoda, Class Insecta) may dictate what is caught, as well as being potentially fraught with pitfalls due to the possibly erroneous assumption that the species populations/subpopulations in question are physiologically–genetically homogeneous
(‘clones’ sensu lato [22]) of S. avenae and the bird cherry-oat aphid, Rhopalosiphum padi (L.) kept under conditions of strict clonal hygiene [23]. All these various studies show that, with the widespread use of such molecular markers employed at different spatial scales ranging from geographic to local, to field plot and to colony, increasingly fine scale levels of genetic variation have been detected
As a direct result of ongoing adaptive ecological forces, including directional selection leading to resistance to pesticides, and other factors such as hymenopterous parasitism, populations of insects may be heterogeneous in space, and in time. This may have a significant consequence in studies involving trapping live insects in which it is taken for granted that the population under investigation is spatially and temporally homogeneous
Summary
I briefly relate how aspects of the temporal sampling of flying insects (Subphylum Hexapoda, Class Insecta) may dictate what is caught, as well as being potentially fraught with pitfalls due to the possibly erroneous assumption that the species populations/subpopulations in question are physiologically–genetically homogeneous. Many of the concerns I discuss may well relate to other flying insects, and other terrestrial as well as aquatic insects and other living organisms, for which I give some examples This is not meant to be a comprehensive overview; rather, it is merely a warning that ecological–evolutionary selective pressures working even over relatively short timescales—i.e., years and decades rather than millennia—may influence what we catch in traps and think are the same entity over extended periods, just as spatially-collected insects were thought to be homogenous until the last 40 years or so (see below). Insects 2018, 9, 153 parasites/parasitoids; habituation to light, sound and pheromone lures; chromosomal/genetic changes affecting physiology and behaviour and pre- and post-zygotic effects; and insecticide resistance
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