Considering the Geographic Diversity of Natural Enemy Traits in Biological Control: A Quantitative Approach Using Orius Predators as an Example

The desirable characteristics of effective natural enemies and the causes for failure of biological control efforts have been discussed extensively in the literature, yet predicting which collection site may yield efficient natural enemies remains a challenge. Insect characteristics, such as morphology, physiology, life history and behavior, often vary across geographic cline and location. These variations may reflect phenotypic plasticity across environments, or genetically based local (demic) adaptation. Parameters such as body size, photoperiod response, thermal tolerance and genetic diversity may greatly influence the outcome of biological control efforts. Therefore, geographic variation in such characteristics may be used to optimize the collection site of efficient enemies to be employed in biological control programs. The first step towards this goal is compilation of data on the trait diversity of promising natural enemies across their geographic distribution range. For example, we used published information to compile a database on the geographic distribution of various traits of 92 Orius species (Heteroptera: Anthocoridae), a genus known for its potential contribution to biological control in IPM systems. We discuss how the widespread distribution of this genus in different ecozones should enable the collection of species and populations that differ in various geographically dependent traits relevant to biological control. Finally, we suggest a quantitative method to optimize collection efforts of natural enemies. This approach balances the effects of several natural enemy traits that vary geographically. Lastly, we demonstrate the use of this method by evaluating the potential employment of two geographically distinct populations of O. albidipennis

Considering the Geographic Diversity of Natural Enemy Traits in Biological Control: A Quantitative Approach Using <i>Orius</i> Predators as an Example

The desirable characteristics of effective natural enemies and the causes for failure of biological control efforts have been discussed extensively in the literature, yet predicting which collection site may yield efficient natural enemies remains a challenge. Insect characteristics, such as morphology, physiology, life history and behavior, often vary across geographic cline and location. These variations may reflect phenotypic plasticity across environments, or genetically based local (demic) adaptation. Parameters such as body size, photoperiod response, thermal tolerance and genetic diversity may greatly influence the outcome of biological control efforts. Therefore, geographic variation in such characteristics may be used to optimize the collection site of efficient enemies to be employed in biological control programs. The first step towards this goal is compilation of data on the trait diversity of promising natural enemies across their geographic distribution range. For example, we used published information to compile a database on the geographic distribution of various traits of 92 Orius species (Heteroptera: Anthocoridae), a genus known for its potential contribution to biological control in IPM systems. We discuss how the widespread distribution of this genus in different ecozones should enable the collection of species and populations that differ in various geographically dependent traits relevant to biological control. Finally, we suggest a quantitative method to optimize collection efforts of natural enemies. This approach balances the effects of several natural enemy traits that vary geographically. Lastly, we demonstrate the use of this method by evaluating the potential employment of two geographically distinct populations of O. albidipennis.</i

Effects of Global Warming on Predatory Bugs Supported by Data Across Geographic and Seasonal Climatic Gradients

Global warming may affect species abundance and distribution, as well as temperature-dependent morphometric traits. In this study, we first used historical data to document changes in Orius (Heteroptera: Anthocoridae) species assemblage and individual morphometric traits over the past seven decades in Israel. We then tested whether these changes could have been temperature driven by searching for similar patterns across seasonal and geographic climatic gradients in a present survey. The historical records indicated a shift in the relative abundance of dominant Orius species; the relative abundance of O. albidipennis, a desert-adapted species, increased while that of O. laevigatus decreased in recent decades by 6 and 10–15 folds, respectively. These shifts coincided with an overall increase of up to 2.1°C in mean daily temperatures over the last 25 years in Israel. Similar trends were found in contemporary data across two other climatic gradients, seasonal and geographic; O. albidipennis dominated Orius assemblages under warm conditions. Finally, specimens collected in the present survey were significantly smaller than those from the 1980’s, corresponding to significantly smaller individuals collected now during warmer than colder seasons. Taken together, results provide strong support to the hypothesis that temperature is the most likely driver of the observed shifts in species composition and body sizes because (1) historical changes in both species assemblage and body size were associated with rising temperatures in the study region over the last few decades; and (2) similar changes were observed as a result of contemporary drivers that are associated with temperature

Field collection sites (2009–10) at three regions along a north to south climatic gradient in Israel (Google earth) (Mountainous Mediterranean - dark grey marks, Mediterranean plain - light grey marks, and Semi-arid - white marks), superimposed over mean annual precipitation isoclines (in mm; Goldreich 2003).

<p>Field collection sites (2009–10) at three regions along a north to south climatic gradient in Israel (Google earth) (Mountainous Mediterranean - dark grey marks, Mediterranean plain - light grey marks, and Semi-arid - white marks), superimposed over mean annual precipitation isoclines (in mm; Goldreich 2003).</p

ANOVA tables¹ for the effect of collection month and region on three morphometric traits of <i>Orius albidipennis</i> and <i>O. niger</i>.

1<p>Two-way ANOVA was used in all analyses except <i>O. albidipennis</i> thorax width and <i>O. niger</i> wing/thorax size ratio, which were analyzed using Mann-Whitney and Kruskal-Wallis tests, respectively, and therefore do not include interactions. P-values lower than 0.05 are indicated in boldface numerals.</p>2<p>Due to small sample size, analysis for <i>O. albidipennis</i> does not include data from the Mountainous Mediterranean region.</p

Thorax width (mm±se) of <i>Orius albidipennis</i> specimens collected during four seasons in the 1980’s compared to those collected in a 2009–10 survey.

<p>Sample size is indicated for each bar.</p

Changes in the relative abundance (%) of <i>Orius</i> species over time.

<p>(A) Comparison of all specimens collected during five periods. (B) Comparison of specimens collected and identified by R. Linnavuori during June-August of 1958 to specimens collected during the same months in the same area in 2009–10. Number of specimens is indicated above each column.</p

Daily mean temperature (°C) recorded over a period of five decades in four meteorological stations representing different climatic regions in Israel: Mt. Kna’an (mesic-Mediterranean climate in the Galilee), Beit Dagan (dry-Mediterranean of central coastal plain), Nahal Hazerim (arid Negev desert) and Eilat (extremely arid southern Arava valley).

<p>Data from the European Climate Assessment & Dataset (<a href="http://eca.knmi.nl" target="_blank">http://eca.knmi.nl</a>).</p

Evolution of physical linkage between loci controlling ecological traits and mating preferences.

Funder: Blavatnik Family Foundation; Id: http://dx.doi.org/10.13039/100011643Funder: Emmy Noether Program; Grant(s): GZ:ME 4845/1‐1Funder: Weizmann Institute of Science; Id: http://dx.doi.org/10.13039/501100001735Coupling of multiple barriers to gene-flow, such as divergent local adaptation and reproductive isolation, facilitates speciation. However, alleles at loci that contribute to barrier effects can be dissociated by recombination. Models of linkage between diverging alleles often consider elements that reduce recombination, such as chromosomal inversions and alleles that modify recombination rate between existing loci. In contrast, here, we consider the evolution of linkage due to the close proximity of loci on the same chromosome. Examples of such physical linkage exist in several species, but in other cases, strong associations are maintained without physical linkage. We use an individual-based model to study the conditions under which the physical linkage between loci controlling ecological traits and mating preferences might be expected to evolve. We modelled a single locus controlling an ecological trait that acts also as a mating cue. Mating preferences are controlled by multiple loci, formed by mutations that are randomly placed in the "genome", within varying distances from the ecological trait locus, allowing us to examine which genomic architectures spread across the population. Our model reveals that stronger physical linkage is favoured when mating preferences and selection are weaker. Under such conditions mating among divergent phenotypes is more frequent, and matching ecological trait and mating preference alleles are more likely to become dissociated by recombination, favouring the evolution of genetic linkage. While most theoretical studies on clustering of divergent loci focus on how physical linkage influences speciation, we show how physical linkage itself can arise, establishing conditions that can favour speciation