Seasonal change in photoperiodic response of the larvae of the lacewing Nineta pallida

Larvae of the lacewing Nineta pallida (Schneider), collected in the field during two seasons, from September to July, were reared in the laboratory under short- or long-day light conditions at 21°C. In autumn and winter, artificial short days delayed the first ecdysis. The influence on the duration of the first instar was maximal (3.4 times longer) when the short days began at hatching time, and later regularly diminished. In spring, the second and third instars showed a reversed response so that the long days now increased the duration of development, although development took no more than 1.4 time as long as in short days. A similar effect appeared in field-collected third instars on and after mid June, reaching its maximum (1.8 time until the cocoon spinning) in July. This sort of photoperiodic effect on the larval development is new to the seasonal adaptation of the life cycle in insects.

---

Résumé Des formes préimaginales (oeufs, puis larves) de N. pallida sont récoltées sur des conifères de montagne (Pyrénées), chaque mois depuis septembre jusqu'en juillet en deux saisons (1983/84 et 1985/86). Elles sont ensuite élevées au laboratoire à 21°C, soit en jours longs (JL=L16:D8), soit en jours courts (JC=L8:D16).Le développement embryonnaire est légèrement plus long s'il se fait en JC. Pour les larves de premier stade récoltées en automne et en hiver, les JC retardent considérablement la première mue et prolongent aussi le deuxième stade qui en provient. L'influence retardatrice est maximale (3,4 fois) lorsque les JC agissent dès l'éclosion. Elle diminue ensuite progressivement et devient insignificante pour les larves récoltées à artir de février.Au printemps, les larves récoltées au deuxième stade ainsi que les troisièmes stades qui en découlent présentent une réaction inverse: ce sont alors les JL qui augmentent la durée du dévelopement, toutefois, pas plus de 1,4 fois par rapport aux JC. Un effet de même ordre se manifeste sur les larves de troisième stade récoltées à partir de juin, atteignant son maximum (1,8 fois) dans le lot de larves de juillet, c'est-à-dire peu avant la fin de la croissance pondérale larvaire et le coconnage.Un tel retardement du développement larvaire hivernal, prolongé au printemps et au début de l'été par une inversion de la réponse à la photopériode, est nouveau comme élément d'adaptation saisonnière du cycle naturel chez les insectes.

     

中国草蛉科二新属记述（昆虫纲：脉翅目）

脉翅目(Neuroptera)草蛉科(Chrysopidae)作为一类重要天敌资源,在我国各地非常丰富,大量的标本有待鉴定。本文主要记述2新属及其所属种类,模式标本均保存于北京农业大学昆虫标本室。     

Associative learning in immature lacewings (Ceraeochrysa cubana)

It is known that many social insects and arthropod predators and parasitoids can learn the association between a resource and volatile cues. Although there are various studies on the effect of experience in immature arthropods on behavior later in adult life, not much is known about the effects of such experiences on immature behavior. This was investigated here in the lacewing Ceraeochrysa cubana (Hagen) (Neuroptera: Chrysopidae). Whereas adults of this lacewing feed on plant‐provided food and honeydew, larvae are voracious polyphagous predators of several insect pests, and therefore important for biological control. Hence, studying the foraging behavior and the effects of learning in immatures of this species is important. We exposed immatures to the volatile methyl salicylate (MeSA), which was either associated with food or with the absence of food. Subsequently, their response to this volatile was tested in an olfactometer. Immatures that had experienced the association of MeSA with food were attracted to it and immatures that were exposed to MeSA during food deprivation were repelled. Subsequently, predator immatures that had experienced the association between MeSA and food were released on a plant without food and were found to use this volatile in locating patches with food. In contrast, larvae without such experience were found equally on food patches with and without the volatile. We conclude that these immature predators are capable of learning the association between volatiles and food, or the absence of food, and use this during foraging.     

Assessment of cotton aphids, Aphis gossypii, and their natural enemies on aphid-resistant and aphid-susceptible wheat varieties in a wheat–cotton relay intercropping system

The cotton aphid, Aphis gossypii Glover (Homoptera: Aphididae), is an important cotton pest in northern China, especially in the seedling stage of cotton. After large scale commercial use of transgenic Bt cotton, cotton aphids became one of the most important cotton pests. A 2‐year study was conducted to evaluate the role of four winter wheat varieties that were resistant or susceptible to wheat aphid, Sitobion avenae Fabricius (Homoptera: Aphididae), in conserving arthropod natural enemies and suppressing cotton aphids in a wheat–cotton relay intercropping system in northern China. The results indicated that wheat–cotton intercropping preserved and augmented natural enemies more than a monoculture of cotton. The density of natural enemies in cotton was significantly different among relay‐intercropping fields with different wheat varieties. The highest density of natural enemies and low cotton aphid populations were found in the treatment of cotton in relay intercropped with the wheat variety Lovrin10, which is susceptible to wheat aphid. The lowest density of predators and parasitoids associated with high cotton aphid populations were found with the wheat variety KOK1679, which is resistant to wheat aphid. The results showed that wheat varieties that are susceptible or moderately resistant to wheat aphid might reduce cotton aphids more effectively than an aphid‐resistant variety in the intercropping system by enhancing predators to suppress cotton aphids during the cotton seedling stage.     

Relative consumption of three aphid species by the lacewing, Chrysoperla rufilabris, and effects on its development and survival

Relative consumption of three aphid species, Aphis gossypii Glover, Myzus persicae (Sulzer) and Lipaphis erysimi (Kaltenbach) (Homoptera: Aphididae), by larvae of the lacewing, Chrysoperla rufilabris (Burmeister) (Neuroptera: Chrysopidae), was determined in the laboratory, together with effects on lacewing development and survival. Percentages of survival of C. rufilabris from first instar to adult eclosion were significantly different among lacewing larvae fed different aphid species. When larvae were fed A. gossypii and M. persicae, all larvae developed to adulthood. All larvae died prematurely when they were fed L. erysimi. Developmental duration of C. rufilabris larvae was significantly shorter when larvae were fed A. gossypii (18.0 d) than when larvae were fed M. persicae (19.2 d). The number of fourth instar aphids consumed during development by C. rufilabris larvae differed significantly among individuals fed different aphid species. Chrysoperla rufilabris consumed an average of 168 M. persicae, followed by 141.6 A. gossypii, and only 26.6 L. erysimi. The percentage of these total number of aphids consumed by each larval stadium of C. rufilabris varied significantly among aphid species. The percentage of A. gossypii consumed by each larval stadium was similar to that for M. persicae, 12.1 and 11.4% by the first instar, 15.7 and 13.1% by the second instar, and 72.2 and 75.5% by the third instar, respectively; whereas in the case of L. erysimi, 23.3% of the total number of aphids were consumed by the first instar, 30.1% by the second instar, and 46.6% by the third instar.     

Species composition, seasonal dynamics and numerical responses of arthropod predators in organic strawberry fields

The species composition and relative abundance of predatory arthropod fauna were studied in organic strawberry fields in northwestern Turkey using sweep net sampling and pitfall trapping (activity density). Arachnida constituted 13.1 and 11.5% of the sweep net and pitfall trap catches, respectively. Among the predatory insects, the most abundant groups were Heteroptera (26.7%), Diptera (25.9%), Coleoptera (16.9%) and Orthoptera (10.8%) in sweep net samples. Coleoptera (84.2%) dominated the pitfall trap catches. Many aphid specific and polyphagous predators reached peak abundance during June and July. Pearson's two-tailed correlations showed a significant and positive relationship between syrphid, coccinellid or chrysopid predator numbers and strawberry aphid density. Aphid density was not significantly correlated with carabid or with nabid abundance. Examination of spatial distribution patterns of all predatory arthropod groups using Taylor's Power Law indicated that most arthropod predators, except carabids, exhibited aggregated dispersion patterns. Coccinellids changed their spatial patterns from a uniform to an aggregated distribution through the season. There was also a significant linear correlation between Anterastes sp. abundance (larvae+adults) and Isophya rectipennis+Poecilimon ricteri (larvae+adults) density at both locations. We observed, for the first time, Anterastes preying on Isophya and Poecilimon species. The seasonal abundance of the major predatory groups were described, and their potential importance in controlling strawberry aphid and other pests is discussed.     

The rare Chrysopidae (Neuroptera) of southwestern Europe

Quantitative surveys of the chrysopid fauna from southwestern Europe, namely the Iberian and Italian peninsulas, France south of 46° N, and the west-Mediterranean Islands, were analysed. A total of 56 species of Chrysopidae were reported, of which three species were abundant. These, Chrysoperla carnea (Stephens, 1836) sensu lato, Dichochrysa prasina (Burmeister, 1839) and D. flavifrons (Brauer, 1850), comprised a large percentage of the specimens. For the rarer species, comments are made on their distributions, the enhanced geographic range of exotic ones, and on levels of endemism and stenotopy.     

草蛉科纳草蛉属研究（Ⅱ）—六新种记述（脉翅目：草蛉科）

本文是纳草蛉属Navasius研究续报(研究Ⅰ见“动物分类学报”第15卷第3期)。报道了纳草蛉属6新种:跃纳草蛉N.igneus sp.nov.,冠纳草蛉N.lophophorus sp.nov.,黑角纳草蛉N.nigricornutus sp.nov.显沟纳草蛉N.phantosulcus sp.nov.康纳草蛉N.sanus sp.nov.及三齿纳草蛉N.tridentatus sp.nov.。     

Chrysoperla rufilabris (Neuroptera: Chrysopidae) females do not avoid ovipositing in the presence of conspecific eggs

Previous experiments have demonstrated that green lacewing (Neuroptera: Chrysopidae) adults could be attracted to field crops using artificial honeydew. To be effective as a biological control method, such a technique would require that the increase in female abundance translate in an increase egg deposition. An experiment was conducted to evaluate whether the honeydew-feeding females of the green lacewing Chrysoperla rufilabris (Burmeister) avoid laying eggs in the presence of conspecific eggs. The potential risk associated with oviposition in a site already occupied by conspecific eggs was also studied. The preference of C. rufilabris larvae for kin and non-kin eggs and the susceptibility of C. rufilabris eggs to cannibalism relative to their age was determined. The results demonstrate that females are not reluctant to oviposit in the presence of conspecific eggs. Larvae show no preference for kin or non-kin eggs, and lacewing eggs become less susceptible to cannibalism as they age. This indicates that the risk of egg cannibalism by neonate in the field may be low. The results are discussed from ecological and biological control points of view.     

Biocontrol of Pests of Apples and Pears in Northern and Central Europe - 3. Predators

Predators of apple and pear pests in northern and central Europe and their use as biological control agents are reviewed. Many natural enemy species are specialized feeders and are able to respond to the population dynamics of particular pest species. The most oustandingly successful example of this is the use of phytoseiid mites, particularly Typhlodromus pyri , against phytophagous pest mites in apple. This mite management strategy is now widespread throughout European apple growing regions. Another example is the use of Anthocoris nemoralis against pear psyllids, Cacopsylla pyricola and C. pyri . Several groups of naturally occurring polyphagous predators, such as chrysopids, coccinellids, syrphids and spiders, also prey on a number of pest species in orchards, contributing generally to the reduction in pest populations. However, they are unlikely alone to prevent pest damage fully and reliably. In seeking biological control opportunities for a particular pest, these polyphagous natural enemies are unlikely to be a high priority. An exception, due to its abundance in orchards, is the common earwig, Forficula auricularia , although this predator may also cause some fruit injury. Another option to consider when reviewing possibilities for biological control in orchards is the introduction of biological control agents. The success rate of this approach, using arthropod predators to control pests of field crops, has been generally poor. Furthermore, mass production methods for predators are likely to be difficult and very costly. The biological supplies industry is constantly seeking culture techniques, largely for arthropod biological control agents of pests of protected crops. It is possible that some future advance may be relevant to orchards, though currently available predators do not appear promising. A careful economic appraisal of the feasibility of use of any potential biological control agent would be prudent before embarking on research.