Biological invasion of European tomato crops by Tuta absoluta: ecology, geographic expansion and prospects for biological control

The tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a devastating pest of tomato originating from South America. After its initial detection in eastern Spain in 2006, it rapidly invaded various other European countries and spread throughout the Mediterranean basin. If no control measures are taken, then the pest can cause up to 80-100% yield losses in tomato crops in recently invaded areas and may pose a threat to both greenhouse and open-field tomato production. The exceptional speed and extent of T. absoluta invasion have called for studies documenting its biology and ecology, while indicating an urgent need for efficient and sustainable management methods. The development of approaches to manage T. absoluta would be facilitated through a detailed revision of information on this pest in its area of origin. This review combines information on the invasion by T. absoluta, its ecology, and potential management strategies, including data that may help the implementation of efficient biological control programs. These programs, together with a variety of other management tactics, may allow efficient integrated pest management of T. absoluta in Europe and Mediterranean Basin countries. © 2010 Springer-Verlag

Impacts of azadirachtin and chlorantraniliprole on the developmental stages of pirate bug predators (Hemiptera: Anthocoridae) of the tomato pinworm Tuta absoluta

Conservation of natural enemies is an important approach for enhancing biological control. Selective insecticides have become important for managing arthropod pests, and the prospects for their use in combination with biological control agents are increasing. In addition, progress has been made in recent decades to develop reduced-risk insecticides that have novel modes of action and, therefore, likely to have a minimum non-target effect. In this study, we use a series of laboratory bioassays to investigate the impact of two reduced-risk insecticides, azadirachtin and chlorantraniliprole, on the egg, nymph and adult stages of two predatory pirate bugs, Amphiareus constrictus (Stal) and Blaptostethus pallescens Poppius (Hemiptera: Anthocoridae), important predators of the tomato pinworm Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). All three stages were exposed to the label recommended field rate of these two insecticides, which is indicated for the control of T. absoluta. Neither azadirachtin nor chlorantraniliprole affected the mortality of adult predators or their egg hatchability, suggesting a safe acute toxicity for these stages. However, azadirachtin and chlorantraniliprole negatively decreased the capacity of predator nymphs to reach the adult stage. This decrease can directly affect the size of the predator population in the next generation, and may undermine the biological control of pests such as T. absoluta. In general, our results call for caution when using these reduced-risk insecticides in integrated programs of chemical and biological control of this pest.A conservação de inimigos naturais é urna estratégia importante para o controle biológico de insetos-praga. O uso de inseticidas seletivos também tem sido importante para o manejo de insetos-praga, e a prospectiva de ter seu uso combinado com agentes de controle biológico tem ganhado espaço últimamente. Além disso, tem ocorrido um grande progresso nas ultimas décadas com relação ao desenvolvimento de inseticidas de risco reduzido que apresentam novos modos de ação, e possívelmente uma menor chance de causar efeitos nao-alvo. No presente trabalho, nós conduzimos uma série de bioensaios em laboratorio para investigar o impacto de dois inseticidas de risco reduzido, azadiractina e clorantraniliprole, sobre os estádios de ovo, ninfa e adulto de dois predadores hemípteras, Amphiareus constrictus (Stal) and Blaptostethus pallescens Poppius (Heteroptera: Anthocoridae), que são importantes inimigos naturais da traça do tomate Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). Todos os três estádios foram expostos à dose de campo destes dois inseticidas, a quai é recomendada para o controle de T. absoluta. Tanto azadiractina como clorantraniliprole nao afetaram a mortalidade dos predadores adultos ou a eclosão de seus ovos para qualquer espécie, sugerindo a ausencia de uma toxicidade aguda para estes estádios de desenvolvimento. Porém, azadiractina e clorantraniliprole afetaram negativamente a capacidade de ninfas dos predadores alcançarem o estádio adulto. Essa redução na capacidade das ninfas alcançarem o estádio adulto pode afetar diretamente o tamanho da população de predadores na próxima geração, um impacto que poderia reduzir o controle biológico de pragas como T. absoluta. Em géral, nossos resultados sugerem a necessidade de cautela quando usar inseticidas de risco reduzido em programas que visam integrar o controle químico e biológico desta praga

Overwintering potential of the invasive leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) as a pest in greenhouse tomato production in Western Europe

The South American tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a devastating pest in tomato crops. After having spread rapidly in the Mediterranean area since its first detection in 2006, it has recently become established in greenhouses in Western Europe. It was assumed that the low temperatures commonly associated with the winters in this area would prevent this exotic species from successful overwintering. However, the observed presence of T. absoluta at the start of the growing season in Belgium sparked a study on its potential to overwinter in Western Europe. In this study, the insect's cold hardiness and overwintering potential was assessed by determining: (1) the supercooling point (SCP) of larvae, pupae, and adults, (2) the lower lethal time (LT) for these stages at 0 and 5 A degrees C, and (3) the reproductive diapause incidence, as indicated by the reproductive performance of females reared at two temperatures (18 and 25 A degrees C) and two photoperiods [16:8 and 8:16 (L:D) h]. The mean SCP recorded for pupae (-16.7 A degrees C) was significantly higher than for adults (-17.8 A degrees C) and larvae (-18.2 A degrees C). Based on estimates of the LT adults demonstrated better cold hardiness than larvae and pupae at both 0 and 5 A degrees C with the median LT of adults averaging 17.9 and 27.2 days, respectively. No reproductive diapause was observed under the tested regimes. The results of this study indicate that T. absoluta is likely to successfully overwinter between two successive tomato crops in commercial greenhouses in Western Europe