No abstract

As moscas-das-frutas (Diptera: Tephritidae) são os principais entraves às exportações de manga nos pólos de fruticultura da Região Sudoeste da Bahia. O presente trabalho teve como objetivo estudar índices de infestação e a diversidade de moscas-das-frutas no pólo de fruticultura de Anagé, BA, visando obter subsídios para o manejo integrado dessas pragas na mangueira, na região. Os estudos foram realizados em 2004 e 2005, nos municípios de Anagé, Belo Campo e Caraíbas, BA, procedendo-se à coleta de frutos de 21 espécies vegetais, nativas e exóticas, e identificação das espécies de moscas associadas. Estimaram-se os índices de infestação em pupários/kg de fruto e pupários/fruto. Os maiores índices de infestação, em pupários/kg de fruto, ocorreram em serigüela (Spondias purpurea L.) com 61,3, juá (Ziziphus joazeiro L.), 38,3 e umbu (Spondias tuberosa L.), 33,1, considerados hospedeiros primários de Anastrepha fraterculus (Wiedemann) e A. obliqua (Macquart). As maiores infestações em pupários/fruto ocorreram em serigüela (0,9); umbu (0,7) e cajarana (Spondias sp.) (0,2). Com base no monitoramento larval, registra-se, para as condições do pólo de fruticultura de Anagé, a ocorrência das espécies Anastrepha fraterculus, A. obliqua, A. dissimilis, A. amita, A. distincta, A. sororcula, A. zenildae e Ceratitis capitata. Registram-se, pela primeira vez, as seguintes associações bitróficas: juá com A. fraterculus, A. obliqua, A. dissimilis e A. distincta; e umbu com A. amita e A. sororcula.

-This research aimed to determine the functional response of parasitoid Aphidius colemani Viereck, by determining the number of mummies of Myzus persicae (Sulzer) formed and its sexual ratio at densities of 20, 40, 60 and 80 2 nd -and 3 rd -instar nymphs on sweet-pepper leaves, at temperature of 21±1ºC. The functional response was also evaluated by calculating the number of attacks of the parasitoid on the host and its search behaviour on leaf discs of sweet-pepper leaves (43mm) in a Petri dish (50mm). The temperature of 23±1ºC and the densities of zero, four, eight, 16 and 32 nymphs of M. persicae were used. A. colemani's functional response was of type II, not only for number of mummies formed (12.4; 22.7; 33.0 and 31.6) but also for number of attacks (0; 4.1; 6.8; 13.2; and 19.2), with a gradual increase in the number of host density and reaching a plateau. The average sexual ratio was 0.57 and showed no significant influence in host density (P≤0.05). The number of contacts made by parasitoid's antennae onto their hosts (encounters) increased gradually with higher host densities, with an abrupt increase in the highest density (32 hosts), indicating an increase in searching behaviour of the parasitoid. The time of the first visit of A. colemani has not varied with the host density. In the presence of hosts it lasted from 1526.9 to 1638.0 seconds; in the absence of host, the parasitoid stayed on the leaf disc for a short time (340.1 seconds).

In parasitoids, host‐habitat odour can influence host searching within the habitat. This is the case in Leptopilina sp. (Hymenoptera, Figitidae), a Drosophila parasitoid searching for larvae by ovipositor probes. This a behaviour can be conditioned to fruit odours. In a previous study, the latency of probing to a fruit odour is reported to have a genetic variability within a laboratory strain. This suggests a link between rapidity of host discovery and fitness. In the present study, this hypothesis is tested by comparing responses to host‐habitat odours between two genotypes of Leptopilina heterotoma Thomson, from the Mediterranean coast (Antibes) and from Burgundy (Tailly). The two genotypes present contrasting rhythms and levels of locomotor activity linked to contrasting interspecific competition in their area of origin. The high activity observed in the Mediterranean genotype is interpreted as an adaptive response to a limited time‐window to win against a competitor species absent in Burgundy. The present study finds differentiation in innate but not learnt responses to host‐habitat odours. The more active genotype (Antibes) has a higher probability and a shorter latency of innate probing to the odours than the less active genotype (Tailly); Antibes females also find larvae and complete infestations more rapidly. Learning equalizes the probability and the latency of probing to the odours in both strains, and increases the probing duration. Innate responses to host‐habitat odours would allow time‐limited insects to increase their reproductive rate, when host predictability is high in the habitat. Selection of faster innate responses to host and habitat cues without evolution of learnt responses indicates that the initial host discovery is more crucial to fitness than subsequent ones.