Improving insect pest management through population genetic data: a case study of the mosquito Ochlerotatus caspius (Pallas)

Abstract

Summary 1.Rationalizing the use of chemicals in pest control programmes is a fundamental goal that is aided by the knowledge of patterns of population connectivity and historical demography. 2. In this study, we used both mitochondrial and nuclear markers to investigate the genetic structure and diversity of the northern Italian populations of Ochlerotatus caspius , a mosquito of great public health and economic impact in Mediterranean countries. 3. A substantial genetic homogeneity was found among populations, with no association of pairwise population differentiation with the geographic distribution or the environmental heterogeneity of the breeding sites. 4. On a regional scale, we hypothesize a historical demographic expansion, probably associated with late Pleistocene palaeoclimatic events. Furthermore, our results suggest that ever since the expansion event, an extensive gene flow is still the major evolutionary force shaping the overall genetic pattern observed. 5. At a local geographic scale, evidence of recent growth in the size of the population was found in several sites. The increased availability of large breeding sites offered recently by rice paddies seem to have played a major role in giving rise to the observed demographic expansions. Indeed, these sites have become more numerous and undergone changes in the management technique (increased number of dry/flood cycles), which enhanced their suitability as breeding habitats. 6. Synthesis and applications . The migration pattern among populations of Oc. caspius in northern Italy appears to be high enough to maintain an extensive genetic homogeneity. Control programmes on a small geographic scale are thus unlikely to be effective. The modern agronomic techniques and the growth of rice paddies seem to have played a role in the recent demographic history of the species in the Po plain. Therefore, satisfactory control programmes should: (i) be focused mainly on rice paddies as breeding habitats; (ii) favour agronomical techniques involving a reduced number of dry/flood cycles; (iii) be carried out on a wide (regional) geographic scale; and (iv) monitor periodically the susceptibility of populations to the compounds used in control campaigns and adopt strategies aimed to avoid the possible spread of resistance alleles.

High Stability of a Mitochondrial Genetic Marker mtCOII in Polish Colorado Potato Beetle Populations

“…Population genetic studies are done with the application of many genetic markers, among them mitochondrial DNA sequences, mostly those encoding mtCOI and mtCOII. These have been successfully applied for the population studies of other insect species (Grapputo et al 2005, Porretta et al 2007, Albernaz et al 2012.…”

Genetic Structure and Demographic History of New World Screwworm Across Its Current Geographic Range

“…This type of control is independently applied by breeders, in accordance with individual and shortterm necessity, without any coordinated program. The wide range of insecticides used to control pests can cause problems, such as environmental contamination (see Porretta et al 2007) and the selection of insecticide resistant strains (Cassida andGary 1998, Hemingway andRanson 2000). In the screwworm, Carvalho et al (2009) and Silva and Azeredo-Espin (2009) found mutations that are correlated with insecticide resistance.…”

“…In the screwworm, Carvalho et al (2009) and Silva and Azeredo-Espin (2009) found mutations that are correlated with insecticide resistance. Thus, the necessity to reduce the use of chemicals and adopt control programs with enhanced speciÞcity for the target species, on the appropriate geographic scale, has been highlighted as a more suitable alternative (Kongan 1998, Porretta et al 2007.…”

Molecular approach for identification of mosquito species (Diptera: Culicidae) in Province of Alessandria, Piedmont, Italy

“…This region, known as the DNA barcode (Barcode of Life Initiative, 2003), was used previously to study the Iranian O. caspius (Azari-Hamidian et al, 2009). For O. caspius in Italy, microsatellite and allozyme polymorphism and mitochondrial COII gene structure are reported (Porretta et al, 2007). Although the nucleotide structure of the ITS2 area of C. pipiens is variable it cannot be used to distinguish between C. pipiens and C. pipiens f. molestus, however, a method based on the analysis of the 5'end of the mitochondrial COI gene can be successfully used to identify mosquitoes of the C. pipiens comlex (Shaikevich, 2007).…”