Greenhouse vegetable production has expanded markedly in Greece in recent years, with tomato (Solanum lycopersicum L.; Solanaceae) constituting the principal large-scale crop. This intensification has been accompanied by the invasion and rapid spread of the tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), which has become one of the most severe constraints on tomato cultivation in the country and has driven the need for sustainable pest management strategies. Among the most widely used biological control agents in Mediterranean greenhouses are the zoophytophagous mirid bugs Macrolophus pygmaeus Rambur and Nesidiocoris tenuis Reuter (Hemiptera: Miridae). Although highly effective predators of T. absoluta eggs and other major pests of tomato, their performance is highly context dependent, being shaped by temperature, population origin, and access to alternative resources. This thesis aimed to evaluate Greek populations of the predatory mirids as locally adapted, sustainable biological control agents, while identifying components governing their effectiveness and integration into greenhouse Integrated Pest Management (IPM) systems. The first study examined the effects of temperature and population origin on key biological parameters of a Greek and a commercial population of N. tenuis at 25 and 30 °C. Results demonstrated that temperature is a major driver of development, food consumption, reproduction, and longevity, while population-level differences highlighted the importance of local adaptation. Both populations exhibited a consistent preference for Ephestia kuenhiella Zeller (Lepidoptera: Pyralidae) eggs over Artemia sp. cysts (Anostraca: Artemidae), highlighting food selectivity with direct implications for rearing efficacy and predator performance. The second study quantified the functional responses of M. pygmaeus and N. tenuis feeding on T. absoluta eggs at two temperatures (20 and 25 °C), comparing age (young and old) and sex classes. Both species exhibited a Type II functional response at all tested conditions. Predation efficacy was strongly affected by sex and age, with females, and particularly young females, exhibiting the highest attack rates at both temperatures. Recognizing that effective biological control also depends on predator establishment and persistence, the third study evaluated the use of bottle gourd (Lagenaria siceraria (Molina) Standl.; Cucurbitaceae) as a novel banker plant in greenhouse tomato cultivation. Through olfactory assays, chemical analyses of volatile organic compounds (VOCs), and greenhouse experiments, bottle gourd was shown to support preyless development of both mirid predators, enhance establishment, and reduce phytophagy-related damage, particularly for N. tenuis. The final study investigated the nutritional mechanisms underlying these effects associated with bottle gourd by analyzing the extrafloral nectar of bottle gourd and assessing the effects of a nectar-mimicking sugar solution on N. tenuis performance. Carbohydrate supplementation reduced factitious food consumption and enhanced egg production, highlighting the potential of plant-derived carbohydrates as complementary resources. Overall, this thesis demonstrated that the effectiveness of predatory mirids is shaped by the interplay of temperature, access to food resources, and other ecological factors. The thesis offers original, system-level insights into population-specific performance, nutritional ecology, and ecological infrastructure that are directly relevant to improving mass rearing and implementation efficacy under Greek agricultural conditions.
Ελένη Ι. Γιακουμή (2026) studied this question.