Vanda Helena Paes Bueno

The risks of negative non-target effects caused by the use of biological control agents to control pests have been a hotly debated issue since the 1980s. However, these discussions are often limited to a few specific case studies. Large-scale region-wide evaluations of risks and benefits of releases of natural enemies are rare. We tracked the names of 1099 biocontrol agents used in arthropod biocontrol in Latin America and the Caribbean, and ranked them according to origin (native or exotic), to their role in pest reduction (significant or not) and negative non-target effects. About 40% of the agents used in this region were of exotic origin. Depending on the type of programme—natural, conservation, classical or augmentative biocontrol—the percentages of natural enemies attaining significant pest reduction were 40 up to 100. Hence, many natural enemies provided benefits in the form of healthy, sustainable and environmentally friendly pest management. The documented risk associated with the use of exotic natural enemies appears to be low, although minor or poorly monitored non-target effects may have gone undetected. In order to limit occurrence of negative non-target effects in the future, first an inventory should be made of native natural enemies including an assessment of whether one or more of these species are able to sufficiently reduce pest populations. Only if effective native biocontrol agents are not found, the use of an exotic natural enemy should be considered after performing an environmental impact assessment indicating a low risk for negative side effects.

O presente trabalho teve como objetivo estudar a biologia e os caracteres morfológicos de Montina confusa (Stal, 1859) (Hemiptera, Reduviidae, Zelinae). O inseto foi coletado em uma plantação de Eucalyptus...

During the past decade, the use of predatory mirids alone or combined with releases of egg parasitoids of the genus Trichogramma have been tested in Europe for biological control of the worldwide invasive pest, Tuta absoluta (Meyrick). Here, we evaluated the control of this pest by the release of the Neotropical mirid Macrolophus basicornis (Stal), the Neotropic/Nearctic parasitoid Trichogramma pretiosum Riley, and by combined releases of the predator and the parasitoid. Tests were conducted in greenhouse compartments during the summer and fall season. Each compartment contained 10 tomato plants in which only the pest was released or the pest with 1 or 2 natural enemies. Plant damage, and pest and natural enemy densities were checked weekly on one apical, medium, and bottom leaf of 5 plants. Both M. basicornis and T. pretiosum significantly reduced T. absoluta density when released alone. Combined releases resulted in a 10% higher reduction during the summer season, but not during the fall season. The damage caused by T. absoluta was significantly higher in control treatments than in all natural enemy treatments: at the end of the summer trial leaves were completely damaged in the control treatment, whereas only up to 25% leaf damage occurred in the natural enemy treatments. Combined releases did not result in lower damage than with releases of either M. basicornis or T. pretiosum. Practical aspects of single and combined releases are discussed.

Biological control activities on 18 (groups of) Caribbean islands are summarized. Many natural enemies were introduced to these islands through Trinidad and Tobago up to 1980. Also, inter-island exchange of biocontrol agents took place. The majority of projects concerned classical biocontrol, while in some cases natural, conservation and augmentation biocontrol were used. Successes were obtained with biocontrol of pests in crops such as arrowroot, citrus, coconut, cotton and sugarcane and of weeds like prickly pear and puncture vine. After 1980, the number of natural enemy introductions decreased, though the region was faced with many invasions by exotic pests, including the citrus leaf miner, citrus blackfly, papaya mealybug, giant African snail, coconut whitefly and pink hibiscus mealybug. Two large region-wide programmes resulted in successful biocontrol of the pink hibiscus mealybug and the papaya mealybug. In addition, biocontrol by a native natural enemy complex was demonstrated for the coconut whitefly and the passion vine mealybug. The Food and Agriculture Organization of the United Nations (FAO) Code of Conduct for the Import and Release of Exotic Biological Control Agents has recently been applied in the region. Farmers Field Schools, with the aim to enable farmers to use IPM and become less dependent on chemical pesticides, are being implemented.

Tuta absoluta (Meyrick; Lepidoptera: Gelechiidae) is a key pest of tomato and is quickly spreading over the world. We conducted an experiment aimed at evaluating the control capacity and risk for plant damage of three Neotropical mirid species, Campyloneuropsis infumatus (Carvalho; Hemiptera: Miridae), Engytatus varians (Distant; Hemiptera: Miridae) and Macrolophus basicornis (Stal; Hemiptera: Miridae) on T. absoluta infested tomato plants in large cages in an experimental greenhouse. During three successive periods of 9 wk each, we followed population development of the three mirids when exposed to T. absoluta, and of T. absoluta alone in separate cages in the greenhouse. We determined weekly the numbers of T. absoluta eggs and larvae per leaf, the number of mirid predators per leaf, the percentage of damaged leaves and fruits by T. absoluta, and the weight of fruits. Two of the mirid predators, C. infumatus and M. basicornis, successfully established on T. absoluta infested tomato plants and significantly reduced T. absoluta numbers, which ultimately resulted in an increased yield. These two mirid species hardly injured tomato plants or fruits as a result of plant feeding. Surprisingly, the species E. varians, which showed high predation rates in laboratory experiments, did not establish and reduce pest populations in any of the tests.

Plants emit volatile compounds in response to insect herbivory, which may play multiple roles as defensive compounds and mediators of interactions with other plants, microorganisms and animals. Herbivore-induced plant volatiles (HIPVs) may act as indirect plant defenses by attracting natural enemies of the attacking herbivore. We report here the first evidence of the attraction of three Neotropical mirid predators (Macrolophus basicornis, Engytatus varians and Campyloneuropsis infumatus) toward plants emitting volatiles induced upon feeding by two tomato pests, the leaf miner Tuta absoluta and the phloem feeder Bemisia tabaci, in olfactometer bioassays. Subsequently, we compared the composition of volatile blends emitted by insect-infested tomato plants by collecting headspace samples and analyzing them with GC-FID and GC-MS. Egg deposition by T. absoluta did not make tomato plants more attractive to the mirid predators than uninfested tomato plants. Macrolophus basicornis is attracted to tomato plants infested with either T. absoluta larvae or by a mixture of B. tabaci eggs, nymphs and adults. Engytatus varians and C. infumatus responded to volatile blends released by tomato plants infested with T. absoluta larvae over uninfested plants. Also, multiple herbivory by T. absoluta and B. tabaci did not increase the attraction of the mirids compared to infestation with T. absoluta alone. Terpenoids represented the most important class of compounds in the volatile blends and there were significant differences between the volatile blends emitted by tomato plants in response to attack by T. absoluta, B. tabaci, or by both insects. We, therefore, conclude that all three mirids use tomato plant volatiles to find T. absoluta larvae. Multiple herbivory did neither increase, nor decrease attraction of C. infumatus, E. varians and M. basicornis. By breeding for higher rates of emission of selected terpenes, increased attractiveness of tomato plants to natural enemies may improve the effectiveness of biological control.

Plants release a variety of volatile organic compounds that play multiple roles in the interactions with other plants and animals. Natural enemies of plant-feeding insects use these volatiles as cues to find their prey or host. Here, we report differences between the volatile blends of tomato plants infested with the whitefly Bemisia tabaci or the tomato borer Tuta absoluta. We compared the volatile emission of: (1) clean tomato plants; (2) tomato plants infested with T. absoluta larvae; and (3) tomato plants infested with B. tabaci adults, nymphs, and eggs. A total of 80 volatiles were recorded of which 10 occurred consistently only in the headspace of T. absoluta-infested plants. Many of the compounds detected in the headspace of the two herbivory treatments were emitted at different rates. Plants damaged by T. absoluta emitted at least 10 times higher levels of many compounds compared to plants damaged by B. tabaci and intact plants. The multivariate separation of T. absoluta-infested plants from those infested with B. tabaci was due largely to the chorismate-derived compounds as well as volatile metabolites of C₁₈-fatty acids and branched chain amino acids that had higher emission rates from T. absoluta-infested plants, whereas the cyclic sesquiterpenes α- and β-copaene, valencene, and aristolochene were emitted at significantly higher levels from B. tabaci-infested plants. Our findings imply that feeding by T. absoluta and B. tabaci induced emission of volatile blends that differ quantitatively and qualitatively, providing a chemical basis for the recently documented behavioral discrimination by two generalist predatory mirid species, natural enemies of T. absoluta and B. tabaci employed in biological control.