Forum: Insects and Temperature—a General Theory

Abstract

Insects are selected for slow development (but relatively fast growth) in spring, but for fast development in summer. These contrasting selection pressures explain five puzzling effects of temperature on insects: growth and development rates increase almost linearly with temperature; genetic variability in development rate is reduced at high (27°C) temperatures; genetic variability in growth rate is reduced at low (15°C) temperatures; development is very slow at the time of emergence after diapause, regardless of the temperature threshold for emergence; and growth is slow at low temperatures, but development is even slower.Insects use temperature to indicate time-of-season. Different species are geared differently to rising temperatures. Insect predators and parasitoids become more effective at high temperatures; and insect population dynamics are not stable in the conventional sense.

The influence of soil temperature on the nesting cycle of the halictid bee Lasioglossum malachurum

“…These results are confirmed by the comparison of nesting activities of "heated" and "unheated" patches and provide clear evidence for an accelerating, physiological effect of higher soil temperature on the development of the larvae. This is consistent with numerous studies on the effect of temperature on development (Eliopoulos and Stathas, 2003;Gilbert and Raworth, 1996;Grafton-Cardwell et al, 2005;Howe, 1967;Kamm, 1974;Melville and Schulte, 2001;Porter, 1988;Whitfield and Richards, 1992). The negative correlation of soil temperature with the duration of provisioning of B1 workers might be due to a longer daily activity of workers at warmer patches, thereby reducing the number of days needed to provision the next brood.…”

“…We hypothesized that due to the well known effect of temperatures on biological processes (Cossins and Bowler, 1987;Gilbert and Raworth, 1996;Howe, 1967), higher temperatures will shorten the different phases of the nesting cycle of L. malachurum. We expected this effect to be strongest during the early stages of the flight season, when weather conditions are cooler and less predictable.…”

Temperature and the development rates of thrips: Evidence for a constraint on local adaptation?

“…For example, it has been proposed that species living closer to the poles have a lower Tm in, but a greater DDR, while those nearer to the equator show the reverse pattern (Trudgill, 1995;Honek, 1996). A similar suggestion has been made for species that emerge in the spring (lower T^n, higher DDR) and summer (higher Tmin, lower DDR) in temperate regions (Gilbert & Raworth, 1996). In consequence, when we compare across species, we should find a negative relationship between Tm in and DDR (Trudgill, 1995;Honek, 1996).…”

“…Insects cannot develop below a threshold temperature and they need to accumulate enough day degrees to complete their life cycle (Campbell et al, 1974;Lamb, 1992;Gilbert & Raworth, 1996;Addo-Bediako, 2000;Danks, 2000). Since the relation ship between an insect's development rate and temperature is essentially linear within favourable temperatures, these values can be estimated by using linear regression (Honek, 1996).…”

Phylogenetic Analysis Reveals New Genus of Ipini Bark Beetle (Scolytidae)

“…Simple linear regression was used with rate and temperature to estimate the lower threshold of development through extrapolation of the model to Y = 0. Only temperatures through which the development rate increased approximately linearly (excluding temperatures higher than would normally be encountered by the insect in nature) were included in this model (Gilbert and Raworth 1996). Larval head-capsule widths were grouped graphically by examining natural breaks in the data, and the rate of change between instars was compared with previous research.…”