Population dynamics and seasonal trend of California red scale (Aonidiella aurantii Maskell) in citrus in Northern Spain

J M Campos-Rivela,J M Fibla-Queralt,M T Martinez-Ferrer

doi:10.5424/sjar/2012101-105-11

Abstract

The California red scale, Aonidiella aurantii (Maskell), was detected in citrus in Catalonia, Northern Spain, in 2000, and has since spread slowly and irregularly southwards, with foci of infestation currently found in southern Tarragona citrus-growing areas. Since Catalonia is the northern citrus growing area in Spain, between 2002 and 2009, the A. aurantii biological cycle (male flights and seasonal history) was studied in two citrus groves and compared with other regions and countries. Population dynamics showed that 4 male flights occur (including that of the overwintering generation) in May, mid June-mid July, August and in October, the most abundant being in August (over 60% of males captured throughout the year). The thermal constant estimated between male flights, using 11.7 ºC as the lower threshold temperature, was 611.8 ± 35.5 DD. Three peaks of sensitive instar were also observed, in early June, late July-early August, and late September. The number of crawlers captured reached a maximum on 27 May (± 1.85 days), 24.8 ± 2.5 days (184.2 ± 18.1 DD) after the first male flight. The male flight abundance showed there was a relationship only between two consecutive generations, revealing the rapid shifts in population abundance. We estimated when the first sensitive instar peak occurred through a non-destructive method, based on the peak of males captured during the first flight.

Highlights

Throughout the world, the California red scale, Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae), is considered the most harmful Diaspididae in citrus groves, where it is difficult to control and causes major economic losses
A. aurantii was first reported in Spain over 70 years ago (Gómez-Menor, 1937), it did not achieve pest status until 1985, when a focus was detected in Alzira, Valencia
Our aim was to study the dispersal of this emergent pest, its population dynamics and seasonal trend patterns in order to compare them with other regions and countries and to thereby improve the management of A. aurantii in our region

Summary

Introduction

Throughout the world, the California red scale, Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae), is considered the most harmful Diaspididae in citrus groves, where it is difficult to control and causes major economic losses. By 2003, A. aurantii had colonised the citrus-growing areas of Valencia province and northern Alicante to different degrees, while in Castellón, it had spread from the original focus detected in 1999 (Alfaro-Lassala et al, 2003). It has spread from its initial focus in the centre of Valencia province, but it is not as prevalent in the northern and southern parts of the region and is absent from northern areas of Castellón (CAPA, 2009). In Valencia, Aonidiella aurantii seems to have a climatic preference for coastal and southern areas, as population maximums are found in the areas where it was first detected (CAPA, 2009) It is present throughout Andalucía, and in Huelva (González-García, 2009), where A. aurantii is the major pest affecting citrus groves. It was detected in Majorca, in 2007, where its spread has been favoured by the abandonment of citrus groves (Rosselló & Olmo, 2009)

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