Importance of feeding behaviour on life cycle in the zoophytophagous bug Dicyphus geniculatus

Abstract

Dicyphus geniculatus (Fieber) (Heteroptera Miridae) is a Mediterranean mirid that has been observed in public green areas in towns of eastern and western provinces of Spain feeding on whiteflies and thrips on Dianthus caryophyllus L. carnations. In this article, the relative importance of feeding behaviour with respect to the duration of nymphal development and nymphal survival, as well as reproduction, was investigated. Nymphs of Bemisia tabaci (Gennadius), larvae of Frankliniella occidentalis (Pergande) and carnation plants introduced into a 50 × 50 × 50 cm methacrylate box, together with adults mirids, in a climate-controlled chamber (25 ± 1 °C, 60 ± 5% HR, 16:8 h L:D photoperiod) were used to analyse feeding behaviour. In particular, data on realised fecundity, sex ratio and adult longevity were analysed. Realised fecundity differed significantly with respect to prey availability (F1, 267 = 44504.92; p ≤ 0.001). The sex ratio did not differ from 1(♂♂):2(♀♀+♂♂) with respect to feeding regimes [“with B. tabaci prey” (37/53+37 = 0.41), χ2 = 1.434, df 1, p = 0.231, “with F. occidentalis prey” (42/50+42 = 0.46), χ2 = 0.200, df 1, p = 0.655] or prey type (B. tabaci or F. occidentalis, χ2 = 0.564, df 1, p = 0.453). Adult longevity differed significantly in terms of prey availability (F2, 534 = 58.89, p ≤ 0.001) and longevity differed for each sex within each feeding regime (F1, 534 = 14.13; p ≤ 0.001). D. geniculatus can survive on a host plant diet exclusively but could not complete its development in the absence of supplemental prey food, indicating that D. geniculatus requires an animal component in its diet. Other zoophytophagous dicyphines are successfully used as beneficials in integrated pest management in horticultural crops. Thus, D. geniculatus has a potential role in the biological control of carnation pests, and therefore may be a promising pest biological control agent, thus contributing to urban area sustainability.