Larval cannibalism and fitness in the stored grain weevils <Emphasis Type="Italic">Sitophilus granarius</Emphasis> and <Emphasis Type="Italic">Sitophilus zeamais</Emphasis>

Resource limitation is an important determinant of life history and behavior while mediating competition and reproduction among organisms. Discreet and closed systems such as grain kernels and seeds impose drastic restrictions to grain beetles that spend their immature stages within a single kernel selected by their mother. This is the case of internally feeding stored grain beetles, such as the grain weevils. Female egg-laying decisions and larval competition largely determine resource limitation for such insects where clustered egg distribution and contest competition with larval interference and cannibalism take place. As the clustered eggs within a grain lead to larval competition and conspecific weevil larvae face each other off during development allowing the emergence of one or two larvae per kernel, we hypothesized that such competition and consequent cannibalism will have fitness consequences for the competing individuals and their offspring. Thus, larvae of the granary weevil (Sitophilus granarius L.) and the maize weevil (Sitophilus zeamais Motsch.) were subjected to larval competition with cannibalism, and lack of it, to assess the potential fitness consequence of cannibalism on these non-carnivorous pest species of stored grains. Larval cannibalism reduced developmental time of maize weevil, but not of granary weevil. However, such condition led to heavier adult weevils of both species exhibiting higher reproductive output generating more and better quality progeny than non-cannibal weevils. These findings indicate direct nutritional benefits of cannibalism to grain weevils favoring their status of key pest species of stored cereal grains.     

Studies on the parasitoids of Gelechia senticetella (Stgr.) (Lepidoptera: Gelechiidae) in Bulgaria

The parasitoids of Gelechia senticetella (Stgr.) (Lepid.: Gelechiidae), a pest of Juniperus excelsa M.?B., were studied in the “Tissata” reserve in Bulgaria. They were reared in laboratory conditions from pest larvae and pupae collected in 1991, 1992 and 2000. As a result of this study, 16 species of parasitoids of G. senticetella were recorded: Habrobracon stabilis Wesm., Hormius moniliatus (Nees), Phanerotoma tritoma Marsh. (Hym.: Braconidae), Diadegma consumptor (Grav.), Liotryphon cydiae (Perk.), Scambus pomorum (Ratz.), Scambus foliae (Cush.), Pimpla turionellae (L.), Eudelus simillimus (Tasch.), Mesochorus sp. (Hym.: Ichneumonidae), Sympiesis acalle Walk., Aprostocetus sp. (Hym.: Eulophidae), Eupelmus urozonus Dalm. (Hym.: Eupelmidae), Copidosoma thompsoni Merc. (Hym.: Encyrtidae), Calliprymna bisetosa Grah., and Mesopolobus sp. (Hym.: Pteromalidae). H. stabilis and P. tritoma were discovered as new species for the fauna of Bulgaria. Three species (E. simillimus, Mesochorus sp. and Aprostocetus sp.) are hyperparasitoids, and the remaining species are primary parasitoids. Most of the parasitoid species attack the larvae of G. senticetella and kill the hosts before pupation. In the studied parasitoid complex, D. consumptor and H. moniliatus were the dominant species. In 1991, the level of total parasitism of the host in the “Tissata” reserve was 24.3?%, in 1992 – 57.9?% and in 2000 – 12.7?%. D. consumptor was the most important parasitoid destroying 26.6?% of the pest larvae in 1992.     

九连山金斑喙凤蝶野外生物学特性观测

[目的]通过连续12 a对金斑喙凤蝶的野外调查观察,研究成虫活动规律,并利用仿生态养殖,观察金斑喙凤蝶卵和幼虫的形态特征与生活习性,研究其生物学特性,以期为金斑喙凤蝶研究与保护提供有效数据。[方法]根据2004—2012年对金斑喙凤蝶成虫活动规律的观察研究,2013—2015年,在金斑喙凤蝶成虫活动期,采用样线踏查的方法,自海拔450 m往山顶海拔1 200 m搜索,调查视野内木兰科植物分布情况,寻找卵和幼虫,收集后带回驻地进行仿生态养殖,观察其形态特征和生活习性。[结果]金斑喙凤蝶在九连山为一年二代,以蛹越冬,第一代成虫发生期为4月上旬至5月中旬,第二代成虫发生期为8月下旬至9月中旬;2013年在木兰科植物金叶含笑上发现卵和幼虫,2014和2015年在深山含笑上发现卵和幼虫,深山含笑为新发现寄主植物,目前除九连山外尚未有报道;幼虫5龄,各龄级幼虫差异较大;预蛹成蛹经历两次蜕皮过程,这是金斑喙凤蝶研究中的一项重大发现。[结论]1)金斑喙凤蝶卵和幼虫的分布与寄主植物分布密切相关,且对生境质量有较高要求,成虫活动范围主要在寄主植物分布范围及其周边;2)金斑喙凤蝶选择生长良好的金叶含笑和深山含笑叶片上产卵,或嗜食深山含笑;3)温度、湿度等环境因子对卵的孵化、幼虫的生长发育以及化蛹和羽化影响较大;4)金斑喙凤蝶雌蝶少,卵孵化率低,幼虫发育历期长,幼虫成活率低,化蛹和羽化率低等是导致其种群数量稀少的主要原因。5)据查,目前尚未有其它蝶类化蛹过程中经历两次蜕皮的报道,预蛹化蛹蜕两次皮是金斑喙凤蝶异于其他蝶类的特殊现象。     

Parasitoids of Saperda populnea (L.) (Coleoptera: Cerambycidae) on aspen (Populus tremula L.) in Bulgaria

The parasitoids of Saperda populnea (L.) (Col.: Cerambycidae) were studied in Bulgaria during the period 1997?–?2001. Galls with pest larvae were collected from young aspen trees at eight locations (Sofia, Kokaliane, Plana, Churek, Gorni Lom, Gintzi, Dolno Kamartzi and Klisura) and examined under laboratory conditions. Four species were reared from 1118 galls containing overwintering pest larvae: Iphiaulax impostor (Scop.) (Hym.: Braconidae), Dolichomitus populneus (Ratz.), Schreineria populnea (Gir.) (Hym.: Ichneumonidae) and Billaea irrorata (Meig.) (Dipt.: Tachinidae). All of the parasitoids were solitary. Schreineria populnea was found as a new parasitoid of the host in Bulgaria. B. irrorata emerged mainly from late-stage S. populnea larvae; the remaining species from both early- and mid-stage larvae. In the parasitoid complex of S. populnea, the most numerous were B. irrorata (59.8?%) and D. populneus (29.4?%). The percentage of host larval parasitism varied from 2.4 to 33.3, with an average of 9.7?%. B. irrorata was the most important in reducing the pest number. The average mortality of S. populnea caused by the tachinid was 5.8?%, and the highest mortality observed in individual study was 20.2?%.     

Association of the pine-infesting Pissodes species with ophiostomatoid fungi in Poland

Bark weevils are consistently associated with various fungi. They act as effective vectors for root-rot fungi, the rust pathogen and the ophiostomatoid fungi. In comparison with bark beetles, the interaction between ophiostomatoid fungi and bark weevils has been poorly studied in Europe. This study aims to clarify the ties among ophiostomatoid fungi and their weevil vectors in Pinus sylvestris. Samples associated with three bark weevils, including Pissodes castaneus, P. piniphilus and P. pini were collected from seven pine stands in Poland. Fungi were isolated from laboratory-reared and field-collected beetles, larvae and galleries of weevils. Isolates were identified based on morphology, DNA sequence comparison for two gene regions (ITS, ß-tubulin) and phylogenetic analyses. Fourteen morphological and phylogenetic ophiostomatoid species were identified among the 1,219 isolates. These 14 species included 11 novel associations between fungi and bark weevils. The most commonly encountered fungal associates of bark Pissodes species were Leptographium procerum, Ophiostoma quercus and O. minus. The spectrum of fungal associates was similar in three bark weevil species, despite some differences between species. Except for P. castaneus, all species of bark weevil were frequently associated with ophiostomatoid fungi. Pissodes castaneus does appear to be a consistent vector of L. procerum and Sporothrix inflata while O. minus, O. quercus and O. cf. rectangulosporium were often found in association with P. piniphilus and P. pini.     

Beobachtungen bei eirser massenvermehrung des eichenerdflohs,Altica quercetorum foud. (Coleopt., chrysomelidae) 1992 bis 1995 in Serbien

Studies onAltica quercetorum Foud. (Coleopt., Chrysomelidae) during an outbreak 1992 – 1995 in Serbia For about 10 years the oak flea beetle,Altica quercetorum Foud. has shown outbreaks at numerous localities in Central and South Serbia. Our observations revealed that the pest preferred mixed stands of sessile and Turkey oaks under nearer preference of the first named oak. Defoliation was caused by the adult insects in early spring, followed by leaf skeletonizing by larvae. In September the adults of the new generation started their secondary feeding. Also a threefold defoliation partly took place during the mass occurrence, in the course of one vegatation period. Outbreaks of this size are new for Serbia. Our researches between 1992 and 1995 deal with the bionomy, gradation and economic importance. The following predators and parasitoids were recorded:Zicrona coerulea L. (Hem., Pentatomidae),Oenopia impustulata L. (Col., Coccinellidae),Microctonus sp. (Hym., Braconidae),Mesochorus palus Schw. (Hym., Ichneumonidae), andMedina luctuosa Meig. (Dipt., Tachinidae).     

Shoot drying and its cause in Calamus simplicifolius at Nanmeiling, Hainan, China

Many stems are subject to shoot drying in the plantations of Calamus simplicifolius Wei at the Nanmeiling Base of the Forestry Bu- reau of Baisha County, Hainan Province. As a palm, stems of C. simpli- cifolius stop growing and later die if the shoots are dry. Generally, shoot drying means reduced cane production and reduced profit for a rattan plantation. We aimed to quantify the incidence of shoot drying and de- termine its reason. We sampled eight 20 m × 20 m plots in the C. simpli- cifolius plantations. In each plot, we counted stems and categorized them as drying shoot or normal shoot, and mother stem or sucker stem. We measured stem length and categorized them as drying shoot and normal shoot for mother stems. We cut open each shoot-drying stem to deter- mine the cause of drying from drying part to fresh part. The frequency of mother stems (259 stem·ha -1 ), was significantly lower than sucker stems (588 stem·ha -1 ). The percentage of shoot drying was 33.8% for mother stems, not significantly higher than that for sucker stems (18.9%). The mother shoot stems were significantly shorter if they were drying than if normal. 80% of stems with a drying shoot were hollow within the leaf sheath, whereas 10% hosted lively mature larvae (one larvae per shoot) and 10% hosted several lively young larvae. Mature larvae were identi- fied as the Red Palm Weevil, Rhynchophorus ferrugineus Oliver. To confirm the present of the weevil, three pheromone traps for the weevil were set up in the plantations and adult weevils were trapped on the nextday and identified as the Red Palm Weevil. We conclude that shoot dry- ing of C. simplicifolius is probably caused by the Red Palm Weevil.     

灭幼脲对杨干象作用机制和防治的研究

采用灭幼脲油剂，油胶悬剂等，用点涂的方法对杨干象幼虫和成虫进行了适时防治，结果表明：灭幼脲油剂可抑制表皮几丁质的合成达１５％以上；灭幼脲油胶悬剂抑制杨干象成虫精巢和卵巢的发育，可使成虫产卵间降低４０－７０％，使卵的孵化率降为零。这为杨干象的防治找到一条高效，安全，经济，易全文的新途径。     

Effects of herbicides on consumption,growth and food utilization by cotton leafwormSpodoptera littoralis (Boisd.) larvae

The deterrent effects of nine herbicides on feeding and growth of cotton leafworm,Spodoptera littoralis (Boisd.), larvae were investigated. Fourth-instar larvae were fed on castor-bean leaves treated with recommended field rates of selected herbicides. Nutritional indices were measured regularly throughout the feeding tests until pupation. The food consumed by larvae in most herbicide-treatments was below that of control. Fluazifop [500 active ingredient (AI)], bentazon (250 AI), ametryne (800, 1600 AI), flamprop (130 AI), and isoxynil (187.5 AI) treatments seemed to be the best feeding deterrents. Relative growth rates of larvae fed on leaves treated with bentazon (250 AI), ametryne (1600 AI), gluphosate (1440 AI), glufosinate (800 AI), and bromoxynil (120 AI) were significantly reduced compared to that in control. Likewise, both the efficiency of conversion of ingested food to body substance (ECI) and the efficiency of conversion of digested food to body substance (ECD) were reduced with herbicide treatments below that in control. Approximate digestibility (AD), however, was significantly increased with most herbicide treatments. Moreover, feeding on herbicide-treated leaves resulted in a significant reduction in both pupation and adult emergence compared to that in control.     

Development of the red palm weevil, Rhynchophorus ferrugineus (Olivier), (Coleoptera, Curculionidae) on natural and synthetic diets

The development of the red palm weevil, Rhynchophorus ferrugineus (Olivier) was investigated on a newly developed semiartificial diet as compared with two natural diets namely sugarcane stem and banana fruit. The weevil was successfully maintained on these diets and duration of the life cycle for males and females, respectively were 164.97 and 194.61 days on the semiartificial diet, 192.5 and 186.5 days on banana, and 172.00 and 170.00 days on sugarcane. The average egg production per female was shown to be significantly higher on the semiartificial diet, being 184.00?±?18.68 eggs compared with an average of 125.00?±?11.97 and 133.00?±?15.21 eggs on banana and sugarcane, respectively. The fertility ranged between 94?–?100?% in those eggs deposited by females previously reared on the tested diets. The developed semiartificial diet was shown to be suitable for maintaining laboratory colonies of the red palm weevil, and it can substitute natural diets.     

Unravelling pest infestation and biological control in low-input orchards: the case of apple blossom weevil

Low-input farming is an alternative production system that provides a great opportunity to disentangle the natural mechanisms regulating crop pests, since neither pests nor their natural enemies are disrupted by pesticides. Here, we use a key apple pest in Europe, the apple blossom weevil (Anthonomus pomorum), as a model case to unravel the factors driving pest infestation and its biological control in a low-input context, namely the cider apple orchards of NW Spain. We applied a holistic approach based on the complete life cycle of the pest and combined large-scale observation (23 orchards) with small-scale experimental assessment. Weevil attack (0.4–37.4% of flowers) increased with the proportion on apple trees in the immediate orchard neighbourhood and with semi-natural woody habitat in the surrounding landscape and decreased with tree distance to orchard edge and apple bloom level. Thus, the prevalence of the pest depended on the availability of the various resources required for foraging, egg-lying and overwintering. Three types of natural enemies supplied complementary pest control by preying on weevils at different stages in their life cycle: seven parasitoid species attacked immature weevils (6.4–81.5%), while the additive effects of birds and crawling arthropods were evident in terms of the removal of adult weevils (31–44%). We conclude that the effective biological control of A. pomorum can be achieved in low-input systems to maintain the pest at non-harmful levels, through combined management of the pest, its habitat and its natural enemies.     

Susceptibility of selected stored product insects to a combination treatment of pyriproxyfen and novaluron

There are many published studies of either insect growth regulators (IGR) or chitinase inhibitors applied directly to larvae of stored product insects or incorporated into their diets, but few studies evaluating efficacy of IGRs or chitinase inhibitors applied alone or in combination with a surface for residual control. Tests were conducted to evaluate susceptibility of Tribolium castaneum (Herbst), the red flour beetle, Trogoderma variabile (Ballion), the warehouse beetle, and Dermestes maculatus (DeGeer), the hide beetle, to Tekko^® Pro which contained the IGR pyriproxyfen and the chitinase inhibitor novaluron as active ingredients. Efficacy was assessed by adult emergence of exposed immatures, an index based on development of those exposed immatures, and progeny production of exposed adults. Concrete arenas were treated with the label rate of the insecticide applied to a surface, and bioassays were conducted at 0–16 weeks post-treatment. No exposed T. castaneum eggs or larvae reached the adult stage and index values for exposed eggs and larvae remained near the minimum. Adult emergence of T. variable from eggs or larvae did not exceed 25% for the first 8 weeks of the test, but at the end of the test at 16 weeks adult emergence was 44 and 71%, respectively, for eggs and larvae. No eggs or larvae of D. maculatus emerged as adults, but excessive cannibalization in untreated controls occurred throughout the test. Results show that Tekko^® Pro will give residual control of T. castaneum and T. variabile, and could replace older conventional neurotoxic insecticides for management of stored product insects.     

Ein praxisnaher Versuch zur Ermittlung der Dauerwirkung von Bacillus thuringiensis Berliner gegen die Dörrobstmotte Plodia interpunctella Hbn in einem Getreideschüttbodenlager

In order to test, under warehouse conditions, the longterm effectiveness of THURICIDE® dust, containingBacillus thrungiensis var.kurstaki (=Serotype H_{3a, 3b}), with a viable spore count of 6 to 10 million per mg, the biopreparation was applied to rye, stored in bulk, on which larvae of the Indian Meal Moth (Plodia interpunctella Hbn.) were fed. From May to October, moth eggs were exposed monthly to rye dusted with 100 mg (320×10³ IU) resp. 150 mg (480×10³ IU) THURICIDE® dust per 100 g grain respectively. At a concentration of 100 mg 0.2% to 2.4% of the larvae, which hatched from the eggs in May, June and August, survived to the adult stage. No moths were observed in the experiments continued during September and October. At a cocentration of 150 mg, only in the experiments started in June and July 2.7% and 0.1% respectively of the eggs and larve survive to become adults. In the experiments of May, August, September and October, none were stated to have survived. The biopreparation-free control of May, June and July showed that about 75% of the eggs/larvae reached the adult stage, whereas, in August, September and October, untreated eggs and larvac reaching the adult stage amounted to 14% and 1% respectively. In reason of the combination of the efficiency ofBacillus thuringiensis and of the only small amount of surviving larvae due to the low temperatures during autumn and winter months, the surface application of THURICIDE® dust would be promising measure for combatting moth pests in bulk-stored grain.     

Zur Wirkung der Nahrungspflanze auf die Entwicklung und Vermeharung der Baumwolleule,Spodoptera littoralis (Boisd.) (Lep.,Noctuidae)

Effect of some host plants on development and reproduction of Spodoptera littoralis (Boisd.) (Lep., Noctuidae) Investigations were performed to study the effect of some hostplants on development and reproduction capacity of the Egyptian cotton leaf-worm,Spodoptera littoralis (Boisd,), Larval and pupal weights, life span, average number of eggs laid per female and percent digestability for fifth instar larvae were measured. Cotton leafworm was able to complete its life cycle only when reared on eigher castor bean leaves, clover, sweet potato leaves, or the outer green cabbage leaves. Chlorophyl-free inner white cabbage leaves, maize, and grape vine are nutritionally insufficient to support growth and development of larvae and, in turn, cause increase in span of survived larvae and none of these larvae metamorph to pupae. It seems that there is a positive correlation between larval and pupal weights and average number of eggs laid per female; the greater the weight of larvae and pupae the higher the number of eggs laid. Castor bean leaves seem to be the most favorable host plant for rearing cotton leafworm in the laboratory. The differences and variations in the growth and development of cotton leafworm due to feeding on different host plants are discussed.     

Monitoring the appearance and possibility for prevention of the apple sawfly in Croatia

The apple sawfly Hoplocampa testudinea Klug has recently become a widespread pest in Croatian apple orchards. It causes severe damage in the blooming period due to the fact that infested fruit fall off. This article shows results collected over three years of field research on trap catches of sawflies, the period of laying eggs, the appearance of larvae and detection of damage. In the climate of northwestern Croatia, adult sawfly appear in April during the blooming period of the early apple variety of Idared. By monitoring temperatures from January 1, adults were detected when the thermal constant reached 210 day-degrees. Our observations showed that the larvae emerged when the sum of thermal constants reached ca. 110 day-degrees. The investigation of effective control strategies with insecticides showed high efficacy of thiametoxam (Actara), imidacloprid (Confidor), thiacloprid (Calypso) and betacyfluthrin + oxydemeton-methyl (Enduro) and lower efficacy of phosalone (Zolone), chlorpyrifos-methyl (Reldan), and lambda cyhalothrin (Karate).     

Activity of heterorhabditid nematodes at high temperature and in combination with cytoplasmic polyhedrosis virus

Percentage survival in aqueous suspensions and infectivity of six Egyptian entomopathogenic nematode isolates from the genus Heterorhabditis varied during the hot period of the year with daily temperature range from 18 to 24?°C. The isolate designated as AS1 had the highest mean of survival (87?%) and infectivity to Galleria mellonella larvae (90?%) after 10 days. When the nematodes coexisted with cytoplasmic polyhedrosis virus of 100 × 10⁶ polyhedra inclusion bodies/ml, which was reproduced within and killed Rhynchophorus ferrugineus larvae, the nematode survival was adversely and progressively affected by the increase in the viral suspension. Among tested concentrations, a viral suspension equal to one-fifth size of the nematode and virus suspension is the best for nematode activity in integrated control against the red palm weevil.     

Persistence of deltamethrin against Hylobius abietis on Norway spruce seedlings

Abstract

The pine weevil Hylobius abietis L. is major threat to forest regeneration in the Nordic countries. The persistence of the deltamethrin insecticide used against pine weevil on Norway spruce seedlings was studied after the seedlings were dipped or sprayed. Insecticide application was timed to occur either before or after frozen storage. Bioassays with the stems of Norway spruce seedlings were used to determine the effect of the insecticide against feeding by the pine weevil. The measures of the control effect were reduction in area of gnawed bark and the state of health of the pine weevils. The concentration of deltamethrin decreased rapidly in seedlings, especially after spraying treatment, which did not efficiently protect seedlings against the pine weevil 6 weeks after planting. There were no signs of degradation of deltamethrin or of an effect on seedling height after frozen storage. In bioassay, the amount of deltamethrin that efficiently prevented feeding by the pine weevil was 5.5 µg g^?1 fresh weight. After one growing season in the field, about 1.76–2.24 µg g^?1 (13–15% of the initial level) of dipped deltamethrin remained in the seedlings. In seedlings treated by spraying, 0.93–0.98 µg g^?1 (7–8% of the initial level) of the deltamethrin remained. According to bioassays, these amounts were no longer sufficient to protect seedlings from feeding by the pine weevil. Therefore, in the first summer, dipping was a significantly more efficient method of application for control of pine weevils.     

Feeding in the Crowns of Scots Pine Trees by the Pine Weevil Hylobius abietis

Hylobius abietis (L.) (Coleoptera:Curculionidae) is the major insect pest of forest regeneration in Europe, where adult weevils kill conifer seedlings by feeding on the bark. This study demonstrates that pine weevils also feed extensively in the crowns of mature coniferous trees. Crown feeding primarily took place during a limited period immediately after the migration to new breeding sites (roots of freshly cut coniferous trees). The weevils reached the crowns mainly by flight and tended to concentrate on trees in freshly cut-over areas. The proportion of sexually mature females successively increased during the crown-feeding period, indicating that they require a certain period of maturation feeding. The pine weevils fed on twigs of 3-20 mm thickness, and they consumed about 0.2-0.3% (200 cm²) of the total bark surface in the crowns of mature Scots pine trees. Calculations suggested that the amount of food consumed in the trees surrounding a fresh clear-cutting should have met the nutrient requirements of the weevil population in the area during the maturation feeding period. In the crowns of shelterwood trees, about 50 cm² of the bark was consumed per tree (0.63 m² ha-1). This level of consumption is not believed to be high enough to relieve the feeding pressure on seedlings and thereby explain the low level of damage usually found under shelterwoods.     

Über Parasitierung und Farbformen des LärchenbockesTetropium gabrieli Weise (Col., Cerambycidae) in Südtirol

In June of 1984 lying stems of larch trees were heaveliy attacked by the larch cerambycidT. gabrieli near Brixen/South Tyrol. From 229 larvae 134 adultTetropium and 95 larval parasites (=41%) emerged. The parasite species were:Rhimphoctona lucida Clém. (Hym., Ichneum.) 55 indiv.;Helcon dentator F. (Hym., Bracon.) 1 indiv., andBillaea triangulifera Zett. (Dipt., Tachin.) 39 indiv. These results are compared with those got bySchimitschek (1929) in ?SR and Lower Austria. Furthermore the different colour formes of the population ofTetropium occurred near Brixen are examined.     

Verschiedene Larvenstadien der Stubenfliege (Musca domestica L.) unter dem Einfluß von Permethrin

Zusammenfassung Die Wirkung unterschiedlich konzentrierter Permethrinlösungen auf verschiedene Altersstadien von Larven der Stubenfliege (Musca domestica L.) wurde untersucht. Folgende Parameter wurden gemessen: Verpuppungsrate, Schlupfrate, Gewicht der Tönnchen, Deformationen der Tönnchen, Prozentsatz der beim Schlupf eingegangenen Fliegen. Kamen 1 Tag alte Maden bzw. Eier mit Permethrin in Kontakt, so wurde die Entwicklung zum schlupfreifen Tönnchen bei um zwei Zehnerpotenzen niedrigeren Konzentrationen unterbunden als bei alten (6 bis 7 Tage) Larven. Notverpuppungen wurden vor allem von alten Maden bei relativ hohen Insektizidkonzentrationen durchgeführt; die dabei entstandenen Tönnchen waren größtenteils deformiert, die Schlupfrate war reduziert, ein relativ großer Teil der Fliegen konnte die Tönnchen nicht vollständig verlassen.

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Different larval stages of the housefly (Musca domestica L.) under the influence of permethrin

During the seven days lasting development of house-fly larvae under laboratory conditions permethrin in graduated concentrations was added to the medium of larvae of different age. The following parameters were measured after the end of the larval development: rate of pupation, rate of hatching, weight of pupae, number of flies which died when they hatched. Rate of pupation and rate of hatching discerned especially when larvae were treated with permethrin one or two days before pupation. At all larval stages weight and morphology of the pupae could be influenced by permethrin, as the number of flies that died when they hatched. Six or seven days old larvae reacted at higher concentrations as young larvae or eggs.

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