Biological control of pests in agricultural field is attaining more attention day by day. Natural enemies of pests cost less and are environmental friendly. Accordingly; Aphidophagous hoverflies is a fundamental predator against aphids (devastating pests )1,2. Among them, aphidophagous hoverflies, Sphaerophoria macrogaster are the leading species3. The aphidophagous female hoverflies have to search flowering plants (insectary plants) to lay eggs. These plants are grown to attract, feed, and shelter natural enemies including parasites and predators. Insectary plants or floral resources have become an vital instrument for conservation biological control (CBC) to boost function of natural enemies against agricultural pests4,5. Therefore, it is essential to select a proper flowering plant for effective foraging by an aphidophagous hoverfly which can enhance the reward (nectar and pollen) by spending less time and energy.
Coriander (Coriandrum sativum Linnaeus) and blue salvia (Salvia farinacea Bentham) are constructive insectary plants, consist of small flowers with shallow corolla. Blue salvia possesses nectar guides, a blue corolla and yellow anthers, effective floral cues for any flower visitor; flowers with similarly colored corolla and anthers were found to be effective floral cues for bumble bees6. These morphological characteristics greatly influence foraging behavior. Both plants were considered potent for foraging by small-sized hoverflies with long, narrow proboscis e.g. S. macrogaster. Coriander has been found competent insectary plant regarding proportion of females laying eggs7.
Chandrima Emtia and Kazuro Ohno designed a study to evaluate foraging patterns of Sphaerophoria macrogaster females in coriander and blue salvia by using a focal sampling method and to determine the appropriate insectary plant for its contribution to biological control of aphids. The sequences and durations of all foraging bouts were recorded during the residence of observed S. macrogaster in each flower patch.
Scientists revealed that foraging interest of hoverfly in particular flowering plant species could be vital for flourishing performance of CBC of aphids with aphidophagous hoverflies. It was concluded that flowering plant species should be selected based on not only attractive floral characters but also with rewards having low handling costs. This investigation will lead to efficient biological control against aphids by using hover flies as natural enemies.
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17 November, 2019