Interactions between the omnivorous bug Nesidiocoris tenuis (Heteroptera: Miridae) and the tomato pests Helicoverpa armigera (Lepidoptera: Noctuidae) and Phthorimaea absoluta (Lepidoptera: Gelechiidae): predation, phytophagy, and prey preference

Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae) is a zoophytophagous bug that can derive nutrients from 3 trophic levels: plants, herbivorous arthropods, and other predators. On tomato, besides damaging the plants as they feed, might the mirid also forage on pest species and repel pests. In greenhouse and laboratory experiments, we investigated the functional response of the bug, its prey preference, and its influence on the oviposition potentials of 2 major pest species Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) and Phthorimaea absoluta Meyrick (Lepidoptera: Gelechiidae) on tomato Solanum lycopersicum L. (Solanaceae). Nesidiocoris tenuis showed a Type II functional response to both prey species. The estimated handling time was higher for H. armigera eggs than for P. absoluta yet N. tenuis attack rates did not differ between the 2 prey species. Nesidiocoris tenuis did not show a preference for 1 species when prey eggs were provided in equal proportions. The feeding on tomato plants by N. tenuis did not affect oviposition by the 2 moth species, as neither species showed a preference for clean or N. tenuis-adult-damaged plants and clean or N. tenuis-nymph-damaged plants. This study shows that N. tenuis can prey upon eggs of both moth species as the 3 species co-occur in tomato fields. However, because of the shorter handling time of P. absoluta eggs by the predator and the higher number of eggs laid by H. armigera, the co-occurrence might be less detrimental to the H. armigera populations compared to P. absoluta

Habitat factors associated with Fopius caudatus parasitism and population level of its host, Ceratitis cosyra

Biotic and abiotic factors affect herbivores and their natural enemies and understanding of their requirements may permit habitat modification enabling conservation biological control. Ceratitis cosyra Walker (Diptera: Tephritidae), an African-native fruit fly pest is mostly parasitized by the parasitoid wasp Fopius caudatus Szepligeti (Hymenoptera: Braconidae). To assess F. caudatus habitat, the wasp parasitism levels and infestation of its fruit fly host were examined in Sarcocephalus latifolius (Smith) Bruce (Rubiaceae), a shrub of which the fruits are among the preferred hosts of C. cosyra and F. caudatus. Fruit-collection site descriptions, including plant species presence, were analysed in relation to the target insect abundances (emergence from target fruit). Ceratitis cosyra and F. caudatus emerged from all sites; nonetheless, their population levels were associated with both abiotic and biotic factors, of which some can be manipulated. Several factors, such as cultivation level, topography, and vegetation coverage, were correlated with F. caudatus parasitism. Ceratitis cosyra infestation level was correlated with factors such as density of S. latifolius, vegetation cover, cultivation practices, temperature, altitude, rainfall pattern, and stoniness. Proximity to other fruit fly host plants correlated with both pest abundance and F. caudatus parasitism level of the fruit fly. The findings that insects' interactions and abundance are influenced by habitat structure and that parasitism is positively related to natural habitat indicates the importance of maintaining natural habitats in closeness to cultivated areas with the aim of enhancing pest suppression by parasitoids. Further studies should attempt to identify how plant species composition in and around orchards could affect the management of tephritid fruit fly pests