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α-Farnesene levels in the outer coating of developing fruit of ten varieties of apple were monitored at fortnightly intervals from fruit set to harvest. The compound was present in all varieties and the total amount on individual fruit increased with increasing fruit size. However, varieties differed in the levels of α-farnesene/unit area of apple skin, with two peaks evident in some varieties during the season. The relationship between varietal and seasonal variation in α-farnesene production and the ecology and behavior of codling moth adults and larvae is discussed.

A crude extract of lucerne root (Medicago sativa ’Wairau') was found to contain a strong feeding deterrent for 3rd‐instar Costelytra zealandica (White) larvae when tested at fresh‐root concentration. Purified saponins obtained from such an extract by standard procedures markedly reduced feeding, and had an ED50 of 0.019%. A commercial preparation of naturally derived saponins was also an effective feeding deterrent, with an ED50 of 0.18%. Considerable variation was found in the saponin levels present in the root of 13 cultivars of lucerne. A role for saponins in the resistance of lucerne to grass grub attack seems probable, but the mechanism of that role remains uncertain.

Crude extracts of root of the resistant pasture plants lucerne (Medicago sativa) and Lotus pedunculatus contain strong feeding deterrents for third instar Costelytra zealandica and Heteronychus arutor larvae. Purified saponins isolated from active crude lucerne root extract markedly reduce grass grub feeding and have an ED of 0.019%. Black beetle larvae are even more sensitive to the material. Separate and chemically distinct feeding deterrent fractions, active against the two insects, have been isolated from Lotus pedunculatus root. The role of feeding deterrents in mediating the non-preference of these insect pests for lucerne and Lotus is discussed.

The addition of a crude extract of Lotus pedunculatus root to a medium containing a strong feeding stimulant for 3rd‐instar Costelytra zealandica larvae reduced ingestion to a negligible level. Two, possibly three feeding deterrents have been isolated from the active extract, and have been partially characterised.

Pasture wireworm, Conoderus exsul (Sharp) fed more on larvae of the Australian soldier fly (Inopus rubriceps (Macquart)) than on germinating wheat seed when given a choice in the laboratory. Conversely, Agrypnus variabilis (Candeze), another wireworm found in New Zealand pastures, fed more on wheat seed. As determined by a serological technique (immuno-osmophoresis), 19% of C. exsul larvae, 20% of A. variabilis larvae and 80% of the adults of a staphylinid, Thyreocephalus oxthodoxus, (Olliff) collected in a pasture, had fed on I. rubriceps larvae. A predation rate of 12 soldier fly larvae/m2/day was estimated for C. exsul larvae. RESUME Determination serologique des Elateridae et des Staphylinidae predateurs d'Inopus rubriceps (Stratiomyidae), et alimentation de ces Elateridae sur vegetaux et animaux Pour determiner la valeur de Conoderus exsul Sharp comme predateur d'Inopus rubriceps Macquart, ravageur des prairies en Nouvelle Zelande, cet elateride a ete sur nourri des vegetaux et animaux. En 72 heures, il s'est alimente plus abondamment sur I. rubriceps que sur grains de ble. Par contre, un autre elateride des prairies, Agrypnus variabilis Candeze, a consomme plus de grains de ble que de I. rubriceps. Une technique serologique, l'immuno-osmophorese, a montre que 19% des larves de C. exsul, 20% de celles de A. variabilis et 80% des adultes du staphylin, Thyreocephalus orthodoxus Olliff recoltes dans la nature, avaient consomme des larves de I. rubriceps. En se basant sur la densite en Elaterides, sur le pourcentage de reactions positives, sur les taux de consommation quotidiens, et la periode d'observation de proies dans le tube digestif des predateurs, on peut estimer que 12 larves/m2/jour de I. rubriceps ont ete detruites par les larves de C. exsul pendant les 7 semaines de la periode utilisee.

Crude extracts of the root of the resistant legume,Lupinus angustifolius, showed feeding deterrent activity toCostelytra zealandica andHeteronychus arator larvae. Nine 5-hydroxyisoflavones were isolated from an active fraction and their feeding deterrent activity and antifungal activity was measured. High feeding-deterrent activity was associated with high antifungal activity with some exceptions.

(1977). Plant Chemicals Influencing Insect Behaviour. New Zealand Entomologist: Vol. 6, No. 3, pp. 222-228.

The influence of natural plant odours on the locomotory behaviour of 3rd‐instar larvae of Costelytra zealandica (White) was studied by observing their movement in glass‐sided test chambers. Through an analysis of the paths followed by individual larvae in single‐option choice‐chamber tests it was possible to evaluate the responses of the larvae to different plant materials. The odour of fresh young perennial ryegrass (Loliumperenne) root was more attractive to the insects than was that of older plants. Larvae were also more strongly attracted to the root of lucerne (Medicago sativa), Lotus pedunculatus, red clover (Trifolium pratense), and white clover (T. repens) than to that of perennial ryegrass. The possible role of volatile chemical factors in plant resistance to grass grub attack is discussed.

The feeding response of 3rd‐instar Costelytra zealandica larvae to 20 amino acids tested individually at 2 concentrations was assessed. Six of these compounds had a phagostimulatory effect; in particular, the ubiquitous amino acids L‐aspartic acid, L‐glutamic acid, and L‐serine induced considerable feeding by the grubs. Ascorbic acid was also a strong feeding stimulant and, in combination with sucrose, evoked an intense behavioural response. A synergistic effect of ‘Salt Mix W on the larval response to sucrose was demonstrated.

Overwintering virginoparae of the aphid Thecabius ffinis differ in many respects from the summer forms, but particularly in the accumulation of large lipid reserves. While the summer forms contain small amounts of several neutral lipids, quiescent individuals are found to contain large quantities of a very few. Offspring of a summer form female become quiescent if deposited and reared at a temperature of 8°, regardless of photoperiod. The developmental rate of quiescent forms collected from the field and placed in a 15° environment in the laboratory is slower than that of normal summer forms, although feeding and wax production begin almost immediately after the transfer has been made. RESUME LATENCE ET RESERVE LIPIDIQUE CHEZ LE PUCERON PEMPHIGINE, THECABIUS AFFINIS Les virginipares hiberaants des souches anholocycliques du Puceron Thecabius affinis (Pemphigine) ne s'alimentent pas et ne produisent pas de cire. Leur contenu lipidique total est presque le double de celui des formes estivales. La Chromatographie en couche mince des extraits lipidiques obtenus des hibernants et des formes estivales montra que, tandis que les derniers contenaient de petites quantites de lipidcs comprenant plusieurs groupes de graisses, les premiers contenaient des quantites rclativement grandes d'un petit nombre de lipides, particulierement des triglycerides et des phospholipides. L'accumulation de cette reserve de graisse ainsi que l'etat latent, semblent etre induits par les basses temperatures. Les descendants de virginipares estivales normales places et eleves a une temperature de 8° au laboratoire, se mirent en latence en 1 a 3 semaines, habituellement au second ou au troisieme Stade. Les formes latentes du second stade recueillies dans la nature et transferees dans une ambiance a 15° commeacerent a s'alimenter et a produire de la cire presque immediatement. Cependant, le taux de developpement de ces insectes etait plus reduit ainsi que le taux de reproduction lorsque commencait la larviposition. On ne sait pas encore si la temperature agit directement sur les insectes et induit la latence, ou si elle agit indirectement par l'intermediaire de la piante hote.

Newly hatched codling moth (Laspeyresia pomonella) larvae are attracted to the skin of the apple cultivar “Sturmer Pippin”. In a closed test chamber the insects orientated and moved rapidly towards freshly cut apple skin. The outer skin of the fruit elicited a considerably stronger olfactory response than did the flesh. Dry filter papers treated with an external chloroform extract of whole apples were highly attractive to codling moth larvae. The behaviour of larvae in the presence of these odour sources has been observed and is manifest as a klinotaxis. The effect of the spatial separation of larvae and whole fruit, and the influence of air movement upon this, have also been investigated. The possible role of olfactory attraction in fruit location by newly hatched larvae is discussed. Zusammenfassung DIE ANLOCKUNG FRISCHGESCHLUPFTER RAUPEN DES APFELWICKLERS (LASPEYRESIA POMONELLA) DURCH APFEL Frischgeschlupfte Raupen des Apfelwicklers (Laspeyresia pomonella), die sich in einem geschlossenen Glasbehalter befanden, wurden zum Duft der Schale reifer Fruchte des “Sturmer Pippin”-Apfels hingezogen. Vor allem die Apfelschale, gleichgultig ob mit oder vollig ohne Fleisch, war fur die Raupen sehr anziehend, wahrend das mit reinem Apfelfleisch nur in geringem Mase der Fall war. Das weist eindeutig darauf hin, das die anziehenden Faktoren hauptsachlich in der Schale selbst enthalten sein mussen. Ein Extrakt wurde hergestellt, indem ganze Apfel 30 min in Chloroform eingetaucht wurden. Trockenes Filterpapier, das mit diesem Extrakt impragniert war, wirkte fur die Raupen ebenso anziehend wie frische Apfelschale. In beiden Fallen liefen die Raupen schnell direkt zur Duftquelle. Ihr Verhalten im Duftgradienten wurde beobachtet und als Klinotaxis eingestuft. Die Rolle des Abstandes der Raupe von der Frucht auf das Geruchsempfinden der Raupe in unbewegter Luft wurde gepruft. Es wurde festgestellt, das die Raupen aus 1,5—2,0 cm Entfernung herbeigelockt werden konnen. Wurden ahnliche Experimente bei leichtem Luftzug gemacht, so anderte sich das Verhalten der Raupen dadurch nicht merklich. Daraus wird geschlossen, das beim Auffinden der Frucht durch die eben ausgeschlupften Raupen die Geruchsanziehung wohl eine grosere Rolle spielen mus, zumal die meisten Eier ja nur wenige Zentimeter von der Frucht entfernt abgelegt werden. Dabei ist aber zu bedenken, das auch andere Faktoren des Lebensraumes das Geruchsempfinden beeinflussen konnen.

Polymorphism in aphids is the general rule. The occurrence and succession of their different morphs in nature has been related to numerous factors. Whereas some of these factors may already influence the morph of the generation exposed to them, others express themselves only in subsequent generations. Major, and sometimes exclusive, importance has been attached to environmental temperature and daylength acting directly on the aphids to induce the production of sexual morphs, and to interactions between aphids in the development of winged individuals or in the production of alate progeny. Although various physiological conditions of the hostplants of aphids have for decades been implicated in the development of winged populations, unequivocal evidence that host-plants do play a role in morph determination has not until recently been obtained. Evidence that dietary factors are indeed involved is currently being obtained by using chemically defined artificial diets. Although non-dietary factors may largely determine which of several genetically possible morphs predominantly express themselves, it is now quite clear from the studies to be reported that dietary factors can have a modifying and sometimes even a dominant effect on the processes affecting the morphological expression of aphids. ZUSAMMENFASSUNG EINFLUSSE DER DIAT AUF DEN POLYMORPHISMUS DER BLATTLAUSE Polymorphismus ist bei den Aphiden die Regel. Das Auftreten und die Aufeinanderfolge ihrer verschiedenen Morphen in der Natur ist auf zahlreiche Faktoren bezogen worden. Wahrend einige dieser Faktoren bereits die Morphen der Generation zu beeinflussen vermogen, die ihnen ausgesetzt ist, kommen andere erst in den folgenden Generationen zum Ausdruck. Uberwiegende und manchmal ausschliesliche Bedeutung wurde der Umgebungstemperatur und der Tageslange zugemessen, die direkt auf die Induktion der Erzeugung von Sexualformen wirken, sowie den Wechselwirkungen zwischen Blattlausen bei der Entwicklung geflugelter Individuen oder bei der Produktion einer geflugelten Nachkommenschaft. Obwohl verschiedene physiologische Zustande der Wirtspflanzen der Blattlause seit Jahrzehnten mit der Entwicklung geflugelter Populationen in Zusammenhang gebracht worden sind, wurde ein unumstoslicher Nachweis, das Wirtspflanzen tatsachlich eine Rolle bei der Morphendetermination spielen, bis vor kurzem nicht erbracht. Nachweise, das Nahrungsfaktoren tatsachlich mitspielen, wurden fortlaufend bei der Benutzung chemisch definierter kunstlicher Diaten erhalten. Obwohl Nicht-Nahrungsfaktoren weitgehend bestimmen konnen, welche der verschiedenen genetisch moglichen Morphen vorwiegend zur Verwirklichung kommen, so geht doch aus den hier vorliegenden Untersuchungen nunmehr vollig klar hervor, das Nahrungsfaktoren eine modifizierende, manchmal sogar eine beherrschende Wirkung auf die Prozesse ausuben konnen, welche die morphologische Ausbildung der Blattlause beeinflussen.

Crude root extracts of the black beetle-resistant legumes red clover, white clover, lupin, Lotus pedunculatus, and lucerne significantly reduced feeding by 3rd-instar black beetle larvae when incorporated in an artificial medium containing a strong feeding stimulant. The same extracts were toxic when administered orally. Lucerne and L. pedunculatus contain particularly active feeding deterrents and toxins. The root of the black beetle-resistant grass Phalaris aquatica (= P. tuberosa), like that of the susceptible perennial ryegrass, had no effect on larval feeding or survival. Lotus pedunculatus was very much more active against black beetle larvae than L. corniculatus or L. corniculatus × pedunculatus.

Over the past two decades, studies of the behaviour of phytophagous insects have increasingly emphasized the role of chemical cues in mediating the relationship between the insect and the food- or host-plant. Nevertheless, the isolation and identification of the plant-derived chemicals involved in various behavioural responses, particularly those perceived as odours, has proceeded slowly. This may be accounted for by two major factors. Firstly, in recent years much effort has been directed towards the elucidation of the chemical nature and behavioural activity of insect sex pheromones and sex attractants. Secondly, the task of designing critical bioassays for specific behavioural responses has become increasingly difficult as the variety of information the insect receives from the plant and the multiplicity of its responses to these have become more evident. Moreover, a single chemical can evoke several responses from a single insect depending very largely upon the physical state of the former and the physiological state of the latter.

Several of 17 carbohydrates stimulated ingestion by black beetle larvae (Heteronychus arator) and of these maltose induced an exceptionally strong response. Only maltose, glucose, fructose and sucrose stimulated feeding by adult beetles.

In recent years a number of aphid species have been successfully reared on chemically defined diets (Dadd & Mittler, 1966; Auclair, 1965; Dadd & Krieger, 1967; Ehrhardt, 1968). The development of such diets has offered an opportunity to study in detail several aspects of the physiology of these insects. In particular, the composition of the artificial diet has been shown to influence the production of winged forms by Myzus persicae (Sulzer) (Mittler & Dadd, 1966; Dadd, 1968). In all studies thus far, the aphids have been maintained in the parthenogenetic condition in order to accumulate data concerning the growth and fecundity of females of successive generations. However, it was clearly of interest to determine whether sexual forms could be produced by diet-reared aphids. If so, further information regarding the sexual reproduction of these insects would be forthcoming. Attempts to achieve this using local strains of Myzus persicae, Aphis fabae Scopoli and Acyrthosiphon pisum (Harris) were unsuccessful, presumably because these strains were anholocyclie (Kunkel, unpubl.). A clone of a green strain of A. pisum, previously found to be holocyclic (Sutherland, unpubl.), was then obtained from England and was cultured at 20° C in a photoperiodic regime of 16 hr light: 8 hr dark per day on young bean plants (Vicia faba). The artificial diet on which the experimental aphids were maintained was formulated according to Dadd (1967) and enclosed in sachets of stretched parafilm (Dadd, Krieger & Mittler, 1967). The aphids were provided with fresh sachets every 3–4 days. Adult apterous females taken from the plant culture were caged in groups of five, and exposed to a photoperiodic regime of 10 hr light: 14 hr dark per day at 15°. Successive batches of larvae deposited by these aphids were maintained in this environment until they were adult and had produced offspring for several days. These developed into oviparae and males. Compared to the sexual forms produced on host plants, these diet-reared individuals grew relatively poorly and mortality was high. Nevertheless, the surviving oviparae deposited numerous eggs, but these remained pale green whereas viable, fertilized eggs deposited by plant-reared oviparae rapidly become black. In the case of aphids reared on host plants in a short-day environment the possibility exists that the photoperiod may act indirectly via the plants and not directly on the insects themselves — a doubt which has been raised concerning Megoura viciae Buckton (von Dehn, 1967). However, our results with A. pisum reared on artificial diet demonstrate, as Lees did for M. viciae (Lees, 1960, 1967), that it is unnecessary to implicate the host plant in the determination of males and oviparae. This does not, of course, exclude the possibility that photoperiod-induced changes in a host plant may play a role as well. Nor have we ruled out the possibility that dietary composition may influence the aphids directly or their response to other environmental stimuli leading to the production of sexual forms.

Role of Host Plant in Production of Winged Forms by a Green Strain of Pea Aphid Acyrthosiphon pisum Harris

SINGH, Pritam, 1972: Bibliography of artificial diets for insects and mites. N.Z. D.S.I.R. Bulletin No. 209: 1-75. (Price: 80 cents).

THE skin of the apple cultivar ‘Sturmer Pippin’ contains one or more chloroform-soluble volatile substances which are highly attractive to newly hatched codling moth (Laspeyresia pomonella) larvae1 . There is now evidence that the factor inducing this olfactory response is the acyclic sesquiterpene α-farnesene (Fig. 1), a compound present in the natural coating of ‘Sturmer’ as well as several other apple and pear varieties2–4. This hydrocarbon has also been isolated from the Dufour's gland of at least two5,6 and possibly more7 species of ant and Blum8 has speculated that it may have a role as a pheromone in these insects.