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Influência da colonização da rizosfera na seleção de hospedeiro vegetal por mirídeos predadores
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Resumo(s)
Muitos produtores de legumes e frutas têm uma baixa tolerância aos estragos causados por pragas.
Predadores zoofitófagos, como Miridae (Heteroptera), estão a tornar-se cada vez mais importantes
para o controlo biológico de importantes pragas agrícolas, embora explorem plantas tanto para a
alimentação como para a oviposição. Apesar da sua importância e amplo uso, os mirídeos atualmente
comercializados podem apresentar aspectos desfavoráveis que limitam a sua utilidade.
Adicionalmente, nos últimos anos, estudos com inoculantes fúngicos têm revelado que a comunidade
na rizosfera pode influenciar o desempenho de herbívoros acima do solo e seus inimigos naturais por
meio dos seus efeitos na planta hospedeira.
Neste estudo pretendeu-se testar a preferência para a oviposição de duas espécies de mirídeos
zoofitófagos, Dicyphus cerastii Wagner e Nesidiocoris tenuis (Reuter), na presença de plantas de
tomate em simbiose com fungos colonizadores das raízes ou da rizosfera, usando fungos micorrízicos
arbusculares e um fungo do género Trichoderma. Assim, colocaram-se em várias gaiolas tomateiros
sem Rhizoglomus irregulare / Trichoderma harzianum e tomateiros micorrizados / com Trichoderma
harzianum. Seguidamente, largaram-se casais de mirídeos para que estes pudessem pôr ovos nas
plantas. Passado 10 dias as plantas foram individualizadas, retirando e contando os adultos que se
encontravam nas plantas. Nos dias seguintes, contou-se o número de ninfas.
A micorriza Rhizoglomus irregulare não colonizou as raízes dos tomateiros, no entanto observou-se
um maior número de adultos de Dicyphus cerastii e ninfas eclodidas de Nesidiocoris tenuis nos
tomateiros colonizados por esta formulação do que de plantas não inoculadas, com valores
estatisticamente significativos. No estudo com Trichoderma, para a atratividade dos adultos não foram
encontradas diferenças estatisticamente significativas. Quanto ao número de ninfas eclodidas,
verificou-se diferenças estatisticamente significativas, tendo a espécie Dicyphus cerastii sido mais
elevada nas plantas inoculadas com Trichoderma harzianum enquanto a espécie Nesidiocoris tenuis
foi mais elevada nas plantas sem Trichoderma harzianum.
Many vegetable and fruit growers have a low tolerance for pest damage. Zoophytophagous predators, such as Miridae (Heteroptera), are becoming increasingly important for the biological control of important agricultural pests, although they exploit plants both for food and for oviposition. Despite their importance and wide use, the mirids currently commercialized may present unfavorable aspects that limit their usefulness. Additionally, in recent years, studies with fungal inoculants have revealed that the community in the rhizosphere can influence the performance of aboveground herbivores and their natural enemies through their effects on the host plant. The aim of this study was to test the preference for oviposition of two species of zoophytophagous mirids, Dicyphus cerastii Wagner and Nesidiocoris tenuis (Reuter), in the presence of tomato plants in symbiosis with fungi colonizing the roots or the rhizosphere, using arbuscular mycorrhizal fungi and a fungus of the genus Trichoderma. Thus, tomato plants without Rhizoglomus irregulare / Trichoderma harzianum and tomato plants mycorrhiza / with Trichoderma harzianum were placed in several cages. Then, couples of mirids were released so that they could lay eggs on the plants. After 10 days, the plants were individualized, removing and counting the adults that were on the plants. In the following days, the number of nymphs was counted. The mycorrhiza Rhizoglomus irregulare did not colonize tomato roots, however, a greater number of adults of Dicyphus cerastii and hatched nymphs of Nesidiocoris tenuis were observed in tomato plants colonized by this formulation than in non-inoculated plants, with statistically significant values. In the study with Trichoderma, for the attractiveness of adults, no statistically significant differences were found. As for the number of hatched nymphs, there were statistically significant differences, with the species Dicyphus cerastii being higher in plants inoculated with Trichoderma harzianum while the species Nesidiocoris tenuis was higher in plants without Trichoderma harzianum.
Many vegetable and fruit growers have a low tolerance for pest damage. Zoophytophagous predators, such as Miridae (Heteroptera), are becoming increasingly important for the biological control of important agricultural pests, although they exploit plants both for food and for oviposition. Despite their importance and wide use, the mirids currently commercialized may present unfavorable aspects that limit their usefulness. Additionally, in recent years, studies with fungal inoculants have revealed that the community in the rhizosphere can influence the performance of aboveground herbivores and their natural enemies through their effects on the host plant. The aim of this study was to test the preference for oviposition of two species of zoophytophagous mirids, Dicyphus cerastii Wagner and Nesidiocoris tenuis (Reuter), in the presence of tomato plants in symbiosis with fungi colonizing the roots or the rhizosphere, using arbuscular mycorrhizal fungi and a fungus of the genus Trichoderma. Thus, tomato plants without Rhizoglomus irregulare / Trichoderma harzianum and tomato plants mycorrhiza / with Trichoderma harzianum were placed in several cages. Then, couples of mirids were released so that they could lay eggs on the plants. After 10 days, the plants were individualized, removing and counting the adults that were on the plants. In the following days, the number of nymphs was counted. The mycorrhiza Rhizoglomus irregulare did not colonize tomato roots, however, a greater number of adults of Dicyphus cerastii and hatched nymphs of Nesidiocoris tenuis were observed in tomato plants colonized by this formulation than in non-inoculated plants, with statistically significant values. In the study with Trichoderma, for the attractiveness of adults, no statistically significant differences were found. As for the number of hatched nymphs, there were statistically significant differences, with the species Dicyphus cerastii being higher in plants inoculated with Trichoderma harzianum while the species Nesidiocoris tenuis was higher in plants without Trichoderma harzianum.
Descrição
Tese de Mestrado, Biologia Humana e Ambiente, 2022, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
Controlo biológico Dicyphus cerastii Nesidiocoris tenuis Fungos micorrízicos arbusculares Fungos endofíticos Teses de mestrado - 2022