When plants are attacked by herbivores, they release plant volatiles called herbivore-induced plant volatiles (HIPVs) to the environment to communicate with higher trophic levels. HIPVs play different ecological roles such as plant-plant interaction, plant-herbivore interaction, tritrophic interaction and other related interactions. Attractiveness of HIPVs to natural enemies in a tritrophic interaction varies depending on species diversity. Under natural and multiple cropping systems, tritrophic interaction is expected to be more complex than single tritrophic interaction with one species per trophic level. In complex tritrophic interaction, diversity of different trophic levels affects attractiveness of HIPVs to natural enemies. From plant diversity point of view, HIPVs mixture emanating from herbivore-damaged multiple plant species are reported to affect behavioral responses and foraging behavior of natural enemies under laboratory and field conditions. Similarly, from herbivore diversity point of view, in nature, plants are commonly attacked by more than one herbivore species. Constituents of HIPVs vary between plants infested by multiple and single herbivore species and this affects the behavioral responses and foraging behavior of natural enemies. This paper reviews recent findings on the role of HIPVs as indirect plant defense in systems with simple tritrophic interaction, and in diverse plants species and diverse herbivore species.

Background: Maize, Zea mays L (Cyperales: Poaceae), is one of the major cereal crops grown in Ethiopia for its food and feed values. Recently, the fall armyworm (FAW) (Spodoptera frugiperda) has become a major challenge of maize production threatening smallholder farmers in the country. Developing effective and smallholder farmers-friendly integrated pest management for FAW is vital. Therefore, a study was conducted to evaluate the effect of night-time light-traps and push–pull integrated system on controlling different life stages (adult, larvae and eggs) of FAW. Methods: The study was conducted in Northern Ethiopia included four treatments; maize monocrop, maize plots with night-time light-trap, a push–pull system, and night-time light-trap and push–pull integrated system. Each treatment was replicated five times. The study was carried out twice involving a rain feed (from July to October 2018) and irrigated (from April to June 2019) experiments. Results: A significantly greater number of FAW moths were captured on traps placed outside maize field plots treated with light-trap and push–pull integrated system than traps placed outside the maize monocrop, light-trap alone and push–pull alone treated plots during the 2018 and 2019 experiment seasons. As a result, a significantly lower number of moths was found inside maize field plots treated with light-trap and push–pull integrated system than the other treatments. The levels of FAW eggs and larval infestation were significantly lower in maize plots treated with the light-trap and push–pull integrated system than the maize monocrops, push–pull alone, and light-trap alone treated plots. The proportion of plants damaged by FAW larvae was significantly lower in maize plots treated with the light-trap and push–pull integrated system relative to maize plots treated with the other treatments. Conclusion: This study proved that a system integrating night-time light-traps and push–pull results in better and more effective control of different stages of FAW than a push–pull system or night-time light-traps alone.

ISHS X International Congress on Cactus Pear and Cochineal: Cactus ? the New Green Revolution in Drylands Effect of tree tobacco leaf extracts on mortality rate of carmine cochineal

The cactus pear (Opuntia ficus-indica) is a crucial plant in Tigray, northern Ethiopia, widely distributed in arid and semi-arid environments. It serves as a seasonal food, and is used in livestock feed, fencing, soil conservation, and environmental protection. Recently, the cactus pear populations in Tigray have been severely affected by an exotic insect, the cochineal (Dactylopius coccus). It damaged cactus pear populations in the region’s southern, southeastern, and eastern zones. The Tigray war that broke out in November 2020 exacerbated D. coccus infestation. A study was conducted in the eastern zone of Tigray to assess the impact of the armed conflict on the trends of this infestation and propose sustainable management approaches for sustainable cactus pear production in post-war Tigray. Both primary and secondary data were collected and analyzed. The findings revealed that D. coccus infestation significantly increased during the war and in the post-war period, compared to in the pre-war period. The number of districts involved and level of D. coccus infestation of cactus pear populations increased. The rapid spread was attributed to the interruption of pest management activities due to the armed conflict. To mitigate the spread and ensure sustainable cactus pear production, this study recommends different management approaches to manage D. coccus dissemination and sustainably produce cactus pear in the region, including pest prevention, suppression, or eradication.