Screen-house based rearing experiments demonstrate innate host shift potential in the cashew mirid- Helopeltis schoutedeni Reuter (Heteroptera: Miridae)

Helopeltis schoutedeni Reuter (Heteroptera: Miridae) is an economic pest of cotton and cashew in West and East Africa. Besides its principal hosts, it also feeds on avocado, guava, mango, castor, coca, tea and sweet potato and is considered polyphagous. In Africa, fruit trees are often intercropped with legumes and cucurbits, likely to serve as alternate host to H. schoutedeni during non-fruiting seasons. However information on the bug’s survival on these apparently non-host crops remains largely unknown. We used three frequent intercrops: cucumber fruit (Cucumis sativus L.) and fresh French bean (Phaseolus vulgaris L.) pods and pigeon pea (Cajanus cajan L.) seedlings to study the developmental time, survival, oviposition and feeding behaviours of the bug under screen house conditions. Newly hatched nymphs reared on these substrates successfully developed into adults with substantially varying average developmental times of 25.7, 25.8 and 33.3 days for French beans, pigeon pea and cucumber respectively. Similarly, survival varied significantly among each instar across host plants with survival highest on pigeon pea seedlings (98-100%) and least on cucumber (48-69%). Significantly more feeding lesions were recorded on French beans and pigeon pea than cucumber (H=9.78; df=2; P <0.008) with more feeding punctures made during scotophase than photophase by at least two folds. Oviposition was only recorded on pigeon pea seedlings. Our findings demonstrate the potential for host switching in H. schoutedeni, an observation in concord with its polyphagous nature. Additionally, we report for the first time its nocturnal feeding habit and portray its reliance on a living host for oviposition. These findings bring to light previously unknown facts about the bug’s life history, likely to reshape the development of management measures.

Key words: cashew mirid, development, host plant, host shift, oviposition, polyphagous,  survival