Population abundance of pomegranate aphid, Aphis punicae (Homoptera: Aphididae), predators in Southwest of Iran

Pomegranate aphid, Aphis punicae Passarini (Hom., Aphididae) is an important pest of pomegranate in Iran. Predators play critical role in natural control of the pest. In this study, seasonal population dynamics of the aphid predators were investigated during two years (2016/2017) in Ilam province, southwest of Iran. Samplings were bi-weekly performed in an experimental pomegranate orchard. Four insect predators, Coccinella septempunctata L., Oenopia congelobata L. (Col., Coccinellidae), Xanthogramma pedisseguum Haris (Dip., Syrphidae) and Chrysoperla carnea Stephens (Neu., Chryspidae) were identified as predators of A. punicae in Ilam. The natural enemies occurred during March to May in both years. The highest and the lowest densities were belong to X. pedisseguum and O. congelobata, respectively. Results of the study can be used for developing integrated pest management program of A. punicae in pomegranate orchards

Olfactory responses of predatory bug, Orius albidipennis, and Parasitoid Wasps, Eretmocerus mundus and Eretmocerus eremicus, to Bemisia tabaci and competitor natural enemies

Background and Objectives Cotton whitefly, Bemisia tabaci (Gennadius), is one of the most important pests of field crops, vegetables, and ornamental plants. Parasitoid wasps, Eretmocerus mundus Mercet and Eretmocerus eremicus Rose and Zolnerowich, as well as predatory bug Orius albidipennis Rueter are natural enemies which are used as biocontrol agents to control B. tabaci and play a critical role in reduction of chemical insecticide application. Materials and Methods In this study, experiments were carried out using a Y-tube olfactometer to determine the impact of volatiles emitted from leaves infested by B. tabaci on attraction of natural enemies. Moreover, the effect of presence of one natural enemy on attraction or repellency of another natural enemy was studied. Results Results of olfactory responses showed that infested cucumber leaves were more attractive for all species of natural enemy species, O. albidipennis, E. mundus and E. eremicus, than healthy leaves. The results also showed that O. albidipennis avoided leaves that both species of parasitoid wasps coexist on them. However, presence of O. albidipennis on the leaves as a competitor did not affect the attraction of the parasitoid wasps to infested leaves. Discussion Induced reactions in damaged plants increase their resistance to invasive pests. These changes can affect the reactions of all organisms around the plants including herbivores, pollinators, natural enemies, and even other plants nearby. Previous research confirms our results on attraction of natural enemies to plants injured by B. tabaci. Avoidance of O. albidipennis of patches containing parasitoids may be due to escape from intraguild predation or other reasons like low quality food in such patches. On the other hand, in this study both parasitoids preferred leaves containing O. albidipennis and whitefly nymphs to leaves with only whitefly nymphs. There is a hypothesis that female parasitoids should not avoid the polyphagous predators because they will lose many oviposition locations, as the number of polyphagous predators is too far in agroecosystems. This theory is corresponding well with the results of our study

Potential impact of climate change on whiteflies and implications for the spread of vectored viruses

Published online: 31 Oct 2018Whiteflies (Hemiptera: Aleyrodidae) are important insect pests causing serious damage to plants and transmitting hundreds of plant viruses. Climate change is expected to influence life history and trophic interactions among plants, whiteflies and their natural enemies. Here, we review the potential impacts of climate change on whiteflies and the likely consequences for agricultural systems. This review concludes that while climatic stress tends to negatively affect life history traits, the effects differ with the tolerance of the whiteflies and the amount of stress experienced. Whiteflies also differ in their adaptability. Better adapted species will likely experience increased distribution and abundance provided their tolerance limits are not exceeded, while species with lower tolerance and adaptation limits will suffer reduced fitness, which will have overall effects on their distribution and abundance in space and time. The majority of methods used to control whiteflies will still be useful especially if complementary methods are combined for maximum efficacy. Parasitism and predation rates of whitefly natural enemies could increase with temperature within the optimum ranges of the natural enemies, although life history traits and population growth potential are generally maximised below 30 °C. Changes in climatic suitability modifying the distribution and abundance of whiteflies, and environmental suitability for plant viruses, will likely affect epidemics of viral diseases. Greater efforts are required to improve understanding of the complex effects of climate change on multi-species and multi-trophic interactions in the agro-ecological systems inhabited by whiteflies, and to use this new knowledge to develop robust and climate-smart management strategies