The Feeding Biology of Adult Lacewings (Neuroptera): a Review
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Trends in Entomology Vol. 12, 2016 The feeding biology of adult lacewings (Neuroptera): a review Dušan Devetak* and Vesna Klokočovnik Department of Biology and Institute of Biology, Ecology and Nature Conservation, Faculty of Natural Sciences and Mathematics, Koroška cesta 160, 2000 Maribor, Slovenia. ABSTRACT Theoretical and practical aspects of Chrysopidae Neuroptera, especially the green lacewings within (green lacewings), which are one of the largest this order, are generally considered as major lacewing families, have been well studied in the components of beneficial entomofauna in context of their use in crop protection [6, 7]. Some neuropteran adults have glycophagous diets that agroecosystems. A review of the knowledge on the feeding habits of adults in the order Neuroptera include sugar-rich foods such as nectar, plant is presented, based on data from the literature. Of fluids and honeydew. the 16 neuropteran families, feeding habits in the Microscopic analysis of the intestinal contents in adults have been documented for 13. A diversity adult lacewings revealed six types of feeding of feeding habits influences the functional strategies (Table 1): morphology of the mouthparts and the structure of the digestive tract. A list of relevant literature is - Carnivorous: Ithonidae (only one species also provided. investigated!), Coniopterygidae, Mantispidae, Ascalaphidae and most Myrmeleontidae; KEYWORDS: lacewings, Neuroptera, integrated - Omnivorous: Hemerobiidae, Osmylidae, most pest management, feeding, predator, pollen, Berothidae, and some Chrysopidae (at least aphids, phylloxerids, mites some species of the genus Chrysopa); - Carnivorous-glycophagous: Sisyridae; INTRODUCTION The lacewings (order Neuroptera) are one of the - Glycophagous (sometimes called glycinophagous): most Chrysopidae; smaller orders of holometabolous insects, containing about 6,000 known species distributed among - Palyno-glycophagous (sometimes called sixteen families (Table 1). Adults and larvae of pollino-glycinophagous): some Chrysopidae most families are predaceous. Within Neuroptera, (genus Chrysoperla and Pseudomallada three predaceous families, namely Chrysopidae, prasinus), Nemopteridae and Crocidae; Hemerobiidae and Coniopterygidae are potentially - Palynophagous (sometimes called the most important in integrated pest management pollinophagous): some Berothidae (Nyrma and and organic farming [1, 2, 3, 4]. Dusty wings Berothimerobius), a few Myrmeleontidae (e.g. (Coniopterygidae) are indeed important predators Brachynemurus yavapai) and some Chrysopidae but usually overlooked because of their small size (the Nothochrysinae subfamily). [5]. Brown lacewings (Hemerobiidae) are used in pest management in several parts of the world. The aim of this paper is to provide a review of the feeding strategies in adult lacewings and to encourage further study and manipulation of this *Corresponding author: [email protected] insect order in future from a holistic perspective. 30 Dušan Devetak & Vesna Klokočovnik Table 1. Feeding habits in adults in the extant families of Neuroptera. Suborder/family Feeding habit Key references/reviews Suborder Nevrorthiformia Family Nevrorthidae unknown (fungal spores?) [14] Suborder Hemerobiiformia Family Ithonidae carnivorous [17] Family Osmylidae omnivorous [19, 45] glycophagous; palyno-glycophagous; Family Chrysopidae [4, 19, 29, 32] palynophagous; omnivorous Family Hemerobiidae omnivorous [4, 19] Family Sisyridae carnivorous-glycophagous [14, 19, 45] Family Coniopterygidae carnivorous [4, 19] Family Dilaridae unknown [53] Family Mantispidae carnivorous [55, 56] Family Berothidae omnivorous; palynophagous [61] Suborder Myrmeleontiformia Family Psychopsidae unknown (carnivorous?) [63, 64] Family Nemopteridae palyno-glycophagous [67] Family Crocidae palyno-glycophagous [69, 70] Family Nymphidae carnivorous [72] Family Myrmeleontidae carnivorous; palynophagous [8, 75] Family Ascalaphidae carnivorous [19] Additionally, we present a few original findings digestive tract of adult Osmylus fulvicephalus of the diet in some antlion species. algae, lepidopteran scales and scattered pollen grains are occasionally observed. A possible explanation A review of the methods for studying intestinal for this observation could be that Osmylus adults contents probably scrape off honeydew spread on twigs A simple method for studying intestinal contents and plant leaf surfaces [10] and swallow the in adult Neuroptera is dissection and mounting of honeydew along with small particles, which may get stuck on the sticky plant surface. the alimentary tract on glass slides and microscopic inspection of food remains. An alternative method Various molecular methods have been developed for studying intestinal contents is inspection of in recent decades for gut analysis of Neuroptera. feces [8]. Sometimes insect bristles are found in A technique using PCR (polymerase chain the digestive tract, which are derived from the reaction) for identifying a definite prey species insect’s own integument as a result of grooming. (Ips typographus) was used in green lacewing larvae Insect bristles or even antennal fragments are [11]. This method seemed to be very helpful in sometimes found in the gut of adult green lacewings the detection of Bremisia tabaci remains even in Chrysoperla carnea sensu lato that are not the guts of adult green lacewing predators, when a predators. This finding can be interpreted as the sequence-characterized amplified region marker result of self-grooming by the insect [9]. In the was used [12]. Feeding biology of adult lacewings 31 Feeding habits in adults Family: Chrysopidae, green lacewings More information has been published on Chrysopidae Suborder: Nevrorthiformia than on any other family of Neuroptera, thanks to Family: Nevrorthidae their role as predators of pest arthropods. Principi Malicky [13] often observed adult nevrorthids on [23, 24] was one of the first to have studied the sticky leaves and assumed that they fed on feeding habits of adult green lacewings by honeydew. Monserrat [14] reported the presence microscopic analysis of the intestinal contents in of a significant quantity of fungal spores in the dissected insects. In the seventies, Hagen et al. digestive tract of two nevrorthid species, Nevrorthus [25] prepared the first comprehensive list of apatelios H. Aspöck, U. Aspöck & Hölzel, 1977 chrysopid species with information on adult and Nipponeurorthus fasciatus Nakahara, 1958. feeding habits. Later, knowledge on the adult Randolf et al. [15] described in details the feeding strategies in Chrysopidae further improved mouthpart morphology in Nevrorthus apatelios, [e.g. 4, 19, 26, 27, 28, 29, 30]. The association of showing strongly sclerotized asymmetrical adult green lacewings with certain plant substrate mandibles. Additional work is needed to establish species is evident [31] when they prey on a more complete picture of the feeding habits in phytophagous insects and when they feed on Nevrorthidae. sweet plant products, honeydew and pollen. Suborder: Hemerobiiformia Most adult green lacewings have a glycophagous feeding strategy. This includes sugar-rich foods Family: Ithonidae, moth lacewings such as products of plant origin (e.g. nectar, plant Two formerly recognized families, Rapismatidae fluids) and insect honeydew. In some green and Polystoechotidae, were recently included in lacewings, e.g. in Chrysoperla and Pseudomallada the family Ithonidae sensu Winterton and prasinus, this feeding regime is combined with a Makarkin [16]. De Jong [17] studied the biology palynophagous strategy, and thus classified as a of an American species Polystoechotes punctatus palyno-glycophagous habit [e.g. 4, 19, 28, 29, 30, 32]. (Fabricius, 1793). Based on observations of Species of the Chrysoperla carnea complex feed dissected individuals of this single species, a on pollen from a variety of plants. In western carnivorous habit was established. Besides France, for example, adults consumed pollen from arthropod fragments, several pollen grains were 28 different plant families, and females consumed found in the foregut [17]. Adaptation to such a more pollen than males [30, 32]. diet could include the asymmetrical mandibles Some adult green lacewings feed on insects (genera described in this species. Anomalochrysa, Atlantochrysa and Chrysopa). The species of the genus Chrysopa consume Family: Osmylidae mites, small insects like aphids, pollen, yeasts and In the past, adult Osmylidae have generally been presumed to feed on food of animal origin [18]. spores of fungi; thus, these green lacewings are In the gut of the European species Osmylus designated as omnivorous [4, 19, 33, 29]. Bozsik fulvicephalus , besides insect fragments, algae, [29] demonstrated that species of the genus fungi, honeydew, pollen and plant fragments were Chrysopa differ on account of the proportions of food items consumed. Some omnivorous species found [10, 19, 20]. This species feeds on small arthropods and does in fact, actively feed on require proteins of animal origin to reproduce, pollen as well [10]. In the gut of Australian even if they are able to survive and maintain their Kempyninae, a subfamily of Osmylidae, New potential with sweet liquids [27]. [21] recorded fungal hyphae, spores, pollen, Only a few green lacewings, belonging to the fragments of bark and foliage and a lesser amount subfamily Nothochrysinae (genera Hypochrysa, of insect fragments. In the past, Osmylus was Kimochrysa, Pamochrysa, Pimachrysa) feed designated