Current Research in Neuropterology. Proceedings of the Fourth International Symposium on Neuropterology. BagnBres-de-Luchon, France, 199 1. Canard, M.,Aspiick, H. & Mansell, M.W. (Eds). Toulouse, France, 1992.4. 341 - 347.

Comparative studies on mouthparts and feeding habits of adult Raphidioptera and (Insecta :Neuropteroidea)

Michael STELZL ~sterreichischeAkademie der Wissenschaften, Graz, Austria

ABSTRACT

The mouthparts of seven species of adult Neuropteroidea representing six different feeding habits were examinated. All show adaptations to their special method of food consumption and to the capture of different prey. The mouthparts are illustrated and discussed relative to diet.

Key words : Raphidioptera, Neuroptera, mouthparts, morphology, feeding habits.

INTRODUCTION

Usually, only two types of diet are manifest in adult Neuropteroidea : a carnivorous type and a phytophagous one. In recent studies (STELZL& GEPP 1990 ; STELZL1990, 1991), the feeding habits of 49 species representing eight families of Neuropteroidea were investigated. Four main types of diet were found. 1. Mainly carnivorous : Myrmeleontidae, , Coniopterygidae. 2. Omnivorous ( prey, pollen, fungi, honeydew) : , Heme- robiidae, Chrysopidae (only the Chrysopa Leach.) 3. Carnivorous-glycinophagous (arthropod prey, honeydew) : Osmylidae, Sisyri- dae . 4. Phytophagous : Chrysopidae (except for the genus Chrysopa), Chrysoperla Steinmann pollino-glycinophagous, other genera mainly glycinophagous. Specialisations were found in Coniopterygidae and Sisyridae, which feed on mites, mainly Eriophyidae. To establish whether these different nutritional types and specialisations are also reflected in the mouthpart morphology, seven species representing the va- rious feeding habits were examined. The studies are based upon ICKERT (1968) who discovered that the mandibular length in carnivorous Chrysopidae is greater than that of phytophagous species. The following species were investigated : Dichrostigma jlavipes (Stein) (omnivorous), Fig. 1, coccajus (Denis & Schiffermiiller) (carnivorous), Fig. 2, Semidalis aleyrodifomuk (Stephens) (carnivorous), Fig. 3, Sisyra fuscata (Fabricius) (carnivorous-glycinophagous), Fig. 4, Hemerobius humulinus Linnaeus (omnivorous), Fig. 5, Chrysopa perla (Linnaeus) (carnivorous), Fig. 6, Mallada prasinus (Burmeister) (phytophagous), Fig. 7.

Fig. 1. Mouthparts of Dichrostigma fivipes. Fig. 2. Mandible of Libelloides coccajus. G = galea ; I = incisor ; L = ligula ; Lb = labium ; Lbp = labial palpus ; LC = lacinia ; M = molar ; Md = mandible ; Mx = maxilla ; Mxp = maxillary palpus. Scale 0.4 mm. Mouthparts of Neuropteroidea

Fig. 3. Mouthparts of Semidalis aleyrodifotmis. Fig. 4. Mouthparts of Si.syra fuscara. Gr = groove ; Lbr = labrum ; other legends as in Figs 1 & 2. Scales 0.2 mm.

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Mouthparts of Neuropteroidea MATERIAL AND METHODS

Imagines were collected in several European countries : Austria, Hungary, France and Germany, by hand-netting and in light-traps. The material was stored in 75 % alcohol. The heads of the imagines were boiled and macerated in potassium hydroxide (KOH) for 10 minutes and then transferred to 75 % alcohol for microscopic investigation. During the investigation the mouthparts were measured and several structures illustrated.

RESULTS

Mouthparts of adult Neuroptera are of the typical biting and chewing type. The mandibles are orthopteroid and show in most cases a sharp incisor and a slightly curved chewing surface : the molar. The mandibles of Raphidioptera also have only one incisor, but the molar is notched (Fig. l), which may be interpreted as a plesiomorphic features. This interpretation is different to drawings in H. As&K, U. AS&K & RAUSCH(1991), where additional teeth on the mandibles are described as incisors. A comparison between Parainocellia ressli (H. Asp6ck & U. Aspock) and Harraphidia laufferi (Navsis) - both are illustrated in H. AsWK, U. ASF~CK& RAUSCH(1991) - shows considerable differences between the two families which may be traced back to differences in feeding habits. Ascalaphidae and some Myrmeleontidae (Palpares Rambur sp.) also show more teeth, but in this case, the incisor is split up into two spikes (Fig. 2) and the interpretation is easy. All other investigated imagines fit more or less into the usual type of asymmetrical orthopteroid mandibles. Only phytophagous Chrysopidae and Coniopterygidae (Figs 7 & 3) have symmetrical mandibles, which is due to the loss of the strong incisor on the left side. Maxillae also conform to the orthopteroid type with two functional adapta- tions. The first is formed by the lacinia and galea, the second by a segmented palp. Both are highly specialized and derived. The most original type is found in Raphidioptera where the palp is short and the galeallacinia complex is covered with setae and shaped like a shovel (Fig. 1). In Hemerobiidae and Chrysopidae, the lacinia is developed into a sharp spoon and the palp has a small process which is covered with sense organs (Fig. 5). ICKERT(1968) called these sense organs rhinaria. Coniopterygidae and Sisyridae have the most specialized types of maxil- lae. In Coniopterygidae, the lacinia is modified into a sharp tooth with a few strong setae and the last segment of the palp has a groove which is surrounded by strong setae (Fig. 3). This groove is also typical for Sisyridae (Fig. 4), but the la- cinia is developed into a spoon as in Hemerobiidae and Chrysopidae. The labium follows the various developments of the maxilla. In all investiga- ted species, the paraglossa and glossa fuse into a ligula. This process is almost complete in Neuroptera, but manifests an early stage of fusion in Raphidioptera (Fig. 1). The labial palps of Chrysopidae and Hemerobiidae are similar to the maxillary palps and also possess a small process with sense organs (Fig. 5). The palps of Coniopterygidae and Sisyridae are expanded distally into a wide area co- vered with hooked setae (Figs 3 & 4). DISCUSSION

The morphology of the mouthparts corresponds exactly with the different types of diet, and shows several useful adaptations for the consumption of food. All species which feed on have mandibles with an incisor that is used to capture prey and to hold them whilst the other mandible dismembers them. The asymmetrical mandibles of Hemerobiidae and Chrysopidae which feed mainly on aphids and other small , and that of Sisyridae which prey on mites are highly specialized for this kind of nutrition. The double incisor in Ascalaphidae and some Myrmeleontidae is an excellent adaptation to the capture of fast-flying or well sclerotisized insects (Diptera and Coleoptera), whereas the jaws of Raphidiidae show a primitive omnivorous expression. The spoon-like lacinia is certainly an adaptation for the consumption of honeydew. This was first claimed by ICKERT (1968) for Chrysopidae, and is now confirmed for other families of Neuroptera, like Hemerobiidae and Sisyridae. The process of the palps of some Chrysopidae and Hemerobiidae is used for palpating the plant surface for prey and honeydew, which represents a non- systematic way of searching for food. Neuropteroidea, which are mainly using their eyes in finding prey animals, like Ascalaphidae and Raphidiidae, do not show this kind of adaptation. Another very specialized and non-systematic method of food consumption is found in Coniopterygidae and Sisyridae. Both feed mainly on Eriophyidae, which are very tiny mites. The search for this prey is carried out by palpating the plant surface with the enlarged areas on the palps. The mites are then caught in grooves on the maxillary palps, which acts as comb. The function of the lacinia in Coniopterygidae is not totally clear, but it may be modified to collect mites from the grooves on the palps. This study shows that many questions still remain to be clarified. The relations of mouthparts of adult Neuropteroidea to the feeding habits represent a large open field.

REFERENCES

ASF~CK,H., ASF~CK,U. & RAUSCH, H., 1991. Die Raphidiopteren der Erde. Eine monographisclte Darstellung der Systematik, Taxonomie, Biologie, C)kologie und Chorologie der rezenten Raphidiopteren der Erde, mit einer zusammenfassenden ubersicht der fossilen Rapkidiopteren (lnsecta :Neuropteroidea). 2 vols, 730 & 550 pp. Goecke & Evers, Krefeld. ICKERT,G. 1968. Beitrage zur Biologie einheimischer Chrysopiden (Planipennia, Chrysopi- dae). Entom. Abh. Mus. Tierk. Dresden 36 (4) : 124-192. STELZL,M. & GEPP,J. 1990. Food-analyses of imagines of central European Myrmeleontidae (Insecta : Neuroptera). In : Mansell, M.W. & Aspock, H. (Eds) Advances in Neuropte- rology. Proceedings of the Third International Symposium on Neuropterology. Berg en Dal, Kriiger National Park, R.S.A., 1988. 205-210. Pretoria, R.S.A. STELZL, M. 1990. Nahrungsanalytische Untersuchungen an Hemerobiiden-Imagines (Insecta, Planipennia). Mitt. Dtsch. Ges. allg. angew. Entomologie 7 : 670-676. Mouthparts of Neuropteroidea

STELZL,M. 1991. Untersuchungen zu Nahmngsspektren mitteleuropSischer Neuropteren-Ima- gines (Neuropteroidea, Insecta) - mit einer Diskussion uber deren Nutzlichkeit als Oppo- nenten von Pflanzenschadlingen. Journal of Applied Entomology 111 : 469-477. WEBER,H. 1974. Grundrg der Znsektenkunde. 640 pp. Fischer, Stuttgart.

Address of author :

Mag. Michael Stelzl Forschungsstelle fiir Okosystem-und Umweltstudien ~sterreichischeAkademie der Wissenschaften HeinrichstraBe 5 A-8010 Graz Austria Bibliography of the Neuropterida

Bibliography of the Neuropterida Reference number (r#): 7310

Reference Citation: Stelzl, M. 1992 [1992.06.??]. Comparative studies on mouthparts and feeding habits of adult Raphidioptera and Neuroptera (Insecta: Neuropteroidea). Pp. 341-347 in Canard, M.; Aspöck, H.; Mansell, M. W. (eds.). Current Research in Neuropterology. Proceedings of the Fourth International Symposium on Neuropterology (24-27 June 1991, Bagnères- de-Luchon, Haute-Garonne, France). Privately printed, Toulouse, France. 414 pp.

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