The effect of DDT and rearing temperature on pecten spine number in larvae of the mosquito Aedes aegypti L.

Pecten spine number has been studied in larvae of Aedes aegypti exposed during development to low temperatures or to DDT at the fourth instar, both of which caused substantial mortality. But neither contingency caused stabilising selection for spine number, in contrast to what was observed in a previous study when larvae were exposed to scum on the surface of the rearing medium. — Two larval colour morphs, yellow and brown, did not differ in spine number.     

Chronic toxicity of cadmium toChironomus riparius Meigen — effects upon larval development and adult emergence

Chronic cadmium toxicity tests were carried out withChironomus riparius Meigen using a static-with-replacement exposure procedure. Significant reductions in larval development, survival and production were detected at 0.15 mg Cd l^–1 a value approximately 5000 times lower than the 48 h LC50 for fourth instar larvae. The first instar appears to be the most critical stage in terms of sensitivity, with the number of adults eventually emerging reflecting first instar mortality. Male emergence was slightly delayed at 0.15 mg Cd l^–1. The results of this study illustrate the importance of chronic toxicity tests in identifying sensitive life cycle stages and explaining pollutant-induced stress.     

A new species of Gastrosaccus (Crustacea,Mysidacea) from beaches in Madagascar

Gastrosaccus madagascariensis sp.nov. is common in thesurfzone of sandy beaches along the east and south coasts ofMadagascar. Morphologically, it is characterised by having sevenlateral spines along each side of the telson; with spines 2–4 andthe penultimate spine being dorso-lateral in origin. One or twospinules are interspersed between the fifth and terminal spines.The fourth exopod segment of pleopod 3 in the male is bulbous, bearing twoterminal barbed unequal spines. A robust and naked seta is alsopresent on the same segment in the male.     

Greenhouse Evaluation of Dose– and Time–Mortality Relationships of Two Nucleopolyhedroviruses for the Control of Beet Armyworm, Spodoptera exigua, on Chrysanthemum

Dose– and time–mortality relationships of baculoviruses in pest insects are important for the determination of effective spraying regimes. A series of experiments with Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) and Spodoptera exigua MNPV (SeMNPV) against synchronized populations of S. exigua larvae in greenhouse chrysanthemum was conducted. Dose– and time–mortality relationships of different virus concentrations and S. exigua target stages were determined and the area foliage consumption was measured. Crop injury was greatly reduced when S. exigua were controlled as second or third instar larvae, whereas virus applications against fourth instar larvae could not prevent considerable crop injury, even at high concentrations. SeMNPV was approximately 10 times as infectious as AcMNPV when applied on greenhouse chrysanthemum. The relative virulence of AcMNPV and SeMNPV corresponded reasonably well with previously published laboratory bioassay data. SeMNPV killed second and fourth instar S. exigua larvae approximately 12 h faster than did AcMNPV in chrysanthemum, but no difference in speed of action was found for third instar larvae. The relative speed of action of AcMNPV and SeMNPV determined in chrysanthemum and in laboratory bioassays did not correspond for third instar S. exigua larvae; laboratory bioassay data can therefore not simply be extrapolated to the crop level.     

Two anisakid nematodes from marine fishes off New Caledonia, including Raphidascaris (Ichthyascaris) nemipteri n. sp. from Nemipterus furcosus

One new and one known species of the ascaridoid family Anisakidae are reported from marine fishes off the southwestern coast of New Caledonia: Raphidascaris (Ichthyascaris) nemipteri n. sp. from the intestine of the forked-tailed threadfin bream Nemipterus furcosus (Nemipteridae, Perciformes) and Hysterothylacium cenaticum (Bruce & Cannon, 1989) from the intestine of the striped marlin Tetrapturus audax (Istiophoridae, Perciformes). R. nemipteri is characterised mainly by the shape (wider than long) of the lips, the length of the spicules (225–399 μm, which represent 2.7–4.2% of the body length), the number (22–33) of caudal pre-anal papillae, the position of the vulva (at 16–20% of the body length), and the presence of cuticular spines on the tip of the female tail. Specimens of H. cenaticum from New Caledonia generally exhibited smaller body measurements than those originally described from Australian waters; the deirids and eggs are described for the first time. Maricostula Bruce & Cannon, 1989 is considered a junior synonym of Hysterothylacium, to which three species are transferred as H. cenaticum (Bruce & Cannon, 1989) n. comb., H. makairi (Bruce & Cannon, 1989) n. comb. and H. tetrapteri (Bruce & Cannon, 1989) n. comb.     

Different responses to temperature in three closely-related sympatric cereal aphids

Cotesia glomerata L. (Hymenoptera: Braconidae) is a parasitoid of early instar larvae of Pieris brassicae L. (Lepidoptera: Pieridae). Late instars of P. brassicae can more often overcome parasitization by hemocytic encapsulation of C. glomerata eggs. Short-term hemocyte responses to parasitization were examined in third and fourth instar larvae of P. brassicae. Total and differential hemocyte counts did not differ between parasitized and unparasitized host larvae. A rapid, but temporary decrease of total hemocyte as well as plasmatocyte numbers was observed immediately after oviposition. Numbers of hemocytes adhering to tissues were shown to be the same in untreated, wounded and parasitized P. brassicae larvae by tracing hemocytes with monoclonal antibodies as markers. The in vitro spreading ability of hemocytes from unparasitized third and fourth instar larvae was lower than that of the last instar's; parasitization, however, had no influence on hemocyte spreading. We therefore suggest that the higher parasitization success of C. glomerata in earlier instars of P. brassicae is mainly due to the low spreading ability of the hemocytes. Abbreviations: ACS – anticoagulant saline; BSA – bovine serum albumin; DABCO – 1,4-diazabicyclo-[2,2,2]-octane; DHC – differential hemocyte count; FITC – fluorescein isothiocyanate; GR – granular cells; LPS – lipopolysaccharide; mAb – monoclonal antibody; OE – oenocytoids; PL – plasmatocytes; PRO – prohemocytes; PS – Pieris saline; PVP – polyvinylpyrrolidone; TBS – tris-buffered saline; THC – total hemocyte count.     

A new Early Miocene genus of the family Sciaenidae (Teleostei, Perciformes) from the eastern Paratethys

A new genus of sciaenid fish Caucasisciaena is erected to accommodate the Early Miocene eastern Paratethys species Perca ignota Smirnov, 1936, which, subsequently, was variously attributed to the modern genera, either Larimus or Otolithoides. The materials examined include 32 specimens from four Caucasian and Crimean localities of Sakaraulian age (Lower Burdigalian). The new genus is based on a unique combination of features, including: parasphenoid with a dorsal rounded bony flange; basisphenoid present; premaxilla with short ascending process forming obtuse angle with alveolar process and ascending/alveolar process ratio about 0.17; anterior premaxillary teeth enlarged; posttemporal with few robust spines along its posterior margin; presence of 25 vertebrae; presence of three tiny supraneurals; dorsal fin with 11 spines plus 22–24 soft rays; anal fin with two spines and 7–8 soft rays; second anal-fin spine long and massive; pectoral fin elongate; scales ctenoid on body and cycloid on head (except for one or two rows of ctenoid scales on the cheek). Paleoecological considerations suggest that Caucasisciaena probably was a predatory fish that inhabited the coastal waters of the eastern sector of the Paratethyan basin.     

Feeding behaviour and morphology of filtering combs of Daphnia galeata

The population of Daphnia galeata Sars from the fish pond Velký Pálenec (Blatná, Czechoslovakia) living in high food conditions (7 mgC l^–1) was characterized by a small size of the filtering comb on the thoracic limb 3, measured as seta length, length of the base of the comb and number of setae (population 1). One month cultivation of this population in low food conditions (1.5 mgC l^–1) in the laboratory resulted in twofold increase in size of the filtering comb (population 2). Filtering and ingestion rates of both populations were measured at eight concentrations of food (approximately 0.025–3.2 mgC l^–1) using ¹⁴C labeled Scenedesmus acutus. The results show that size of the filtering combs influences considerably feeding behavior of Daphnia. The comparison of animals with the same body length suggests that the population with a large comb feeds at concentration of food below 0.4 mgC l^–1 more intensively and reaches the maximum of the filtering rate at a lower concentration than the population with a small comb. The situation is opposite at concentration above 0.4 mgC l^–1. The higher values of theoretical flow in population with a small projection of filtering area suggest that this population has to compensate disadvantage of a small comb with the higher appendages beat frequency.     

Die Calyptopis- und Furcilia-Stadien vonEuphausia hanseni (Crustacea: Euphausiacea)

The larval development is discussed and calyptopis stages I–III as well as furcilia stages I–VII are described. The larval development is similar to that ofE. spinifera, E. longirostris andE. triacantha (group d of genusEuphausia). Antennule, antenna, mandible, maxillule, maxilla and spines on the telson are unsuitable for identifying the larvae of different species of the genusEuphausia. The following characteristics can be used to distinguish the different larvae: form and marginal spines of the carapace, form of the rostrum, spines on the segments of the abdomen, and number and form of the pleopods. The mandible of larval Euphausiacea produces an asymmetric lacinia mobilis and a pair of processus incisivus accessorius (spine row). These two appendages are lacking in adult Eucarida.

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Mitglied der Taxonomischen Arbeitsgruppe an der Biologischen Anstalt Helgoland     

Requirements for molting of the crochet epidermis of the tobacco hornworm larva in vivo and in vitro

Summary In the tobacco hornworm,Manduca sexta, the epidermis which underlies the larval crochets is the first tissue to become independent of the prothoracic glands (PG) in a larval molt. In each successive larval molt, crochet forming cells increase in size, form hooks at their distal ends and, finally, secrete cuticle. This paper examines the endocrine requirements for competence to molt and describes parallel cultures in vivo and in vitro to define the hormonal control of crochet molting. When implanted into a fourth instar host larva prior to initiation of the last larval molt, competent crochet epidermis molted, forming crochets synchronously with its host. In the fourth instar, competence to form crochets is attained slowly during the first two days following ecdysis from the third instar. During the feeding phase of the fifth (last) instar, the crochet epidermis remains competent to molt (to form an extra sixth instar set of crochets) until the larva attains a weight of about 4.5 gm. Then, concurrent with the decline in the titer of juvenile hormone (JH) in the hemolymph, competence to form crochets declines. A similar loss of competence did not occur when fourth instar crochet epidermis was exposed to a declining JH titer by culture in either fourth instar isolated abdomens for 72 h or in fifth instar host larvae between 4 and 7 gm. Responses of crochet epidermis cultured in vitro also were examined. Competent fourth instar crochet epidermis formed crochets following 3–6 h exposure to ecdysone in vitro. Six ×10^–7M -ecdysone was required for 50% response, whereas a 10–50-fold higher concentration of -ecdysone was necessary. Although formation of morphologically complete crochets in vitro proceeded with similar time course to that in situ, no molt-induced growth occurred in vitro. When crochet epidermis was exposed to ecdysone in vitro immediately after explantation, exogenous JH was not required for molting. But when tissue was first cultured for 72 h without hormones, subsequent molting in vitro could not be elicited, although molting still could occur when the tissue subsequently was implanted into a fourth instar host. Exposure to corpora allata or to JH during the 72 h of culture in vivo partially prevented the loss in capacity to respond to ecdysone in vitro, suggesting that JH may be one factor involved directly or indirectly in maintenance of tissue responsiveness.Preliminary presentation of some of this work given at the December, 1973 Meeting of the American Society of Zoologists (Fain and Riddiford, 1973)     

X-ray-induced recombination during oogenesis in the silkworm (Bombyx mori L.)

Summary The physical induction of recombinational events has been studied in the female silkworm (Bombyx mori), in which crossing-over does not normally occur. Female silkworms heterozygous in the trans type of two egg-color genes,pe (V-0.0) andre (V-31.7), received a single dose of X-rays (1000 R) at various developmental stages. Then they were crossed to marked males homozygous for both genes. The results indicated that X-rays increase the occurrence of recombinational events in silkworm females from first instar larvae to late stage pupae. The spontaneous frequency of exchange type recombinants in the control series was 2.5 x 10^–5, while after irradiation the frequency of these recombinants was up to 38.8 x^10–5. The sensitive stage to X-ray-induced recombinational events was late stage larvae from fourth to fifth instar. Exchange (cross-over) type recombinants were about three times more frequent than interchange types among the 122 recombinants recovered. The biological significance of the present finding is discussed.     

Periodic shedding and replacement of venomous caudal spines,with special reference to South American freshwater stingrays,Potamotrygon spp.

Synopsis The number of venomous caudal spines and their length and position relative to one another were determined in seven species of South American freshwater rays (Potamotrygonidae) and eight marine or euryhaline species of four families from the Caribbean Coast of South and Central America. Most species have two visible spines at certain stages in the shedding-replacement cycle and only one visible spine at other stages (following shedding). If we include the embryological beginnings of the spines before they erupt and become visible, the spine counts of most rays are actually 2 rather than 1 or 2. Since most species apparently follow this pattern, spine counts are of little use in distinguishing between species except in the relatively few that may have only one, or no spines. Eight captive Potamotrygon specimens maintained in simulated tropical temperature conditions over 12 months showed periodic shedding and replacement of spines. The molts were biannual for a given ray but annual for a given spine. They alternated between two spine loci and their cycles were approximately six months out of phase with each other. Recent studies on Dasyatis sabina by others report only one molt per year, with replacement spines forming always posterior to the primary spine rather than alternating between posterior and anterior. Supernumerary spines (counts of more than two, up to five) are also discussed, as are counts of one and zero.     

The efficacy of Scenedesmus morphology as a defense mechanism against grazing by selected species of rotifers and cladocerans

Phytoplankton often develop various defense mechanisms in response to zooplankton grazing, such as spines and colonies. While it is now known that increased spine length and cells in a colony of members of the genus Scenedesmus, when zooplankton grazing is intense, helps in reducing zooplankton filtering rates, the effect of these defense mechanisms at the population level has been observed in few studies. Here we present data on the growth rates of four zooplankton species, Brachionus calyciflorus, B. patulus, Ceriodaphnia dubia and Daphnia pulex at two food levels using two species of colony-forming Scenedesmus spp.: S. acutus (cell length = 18.2 ± 0.4 µm; width = 4.2 ± 0.1 µm; average colony length = 90 µm; width: 21 µm) and S. quadricauda (cell length: 21 ± 0.5 width 7.5 ± 0.3 µm; average colony length: 84 µm; width: 30 µm). Whereas S. acutus had no spines, S. quadricauda had spines of 6–10 µm. Population growth experiments of the test rotifers and cladocerans were conducted in 100 ml containers with 50 ml of the medium with test algae. Algae concentrations used were: 13 and 52 mg dw l^–1 of each of the two algal species offered in colonial forms. We used an initial inoculation zooplankter density of 1 ind. ml^–1 for either of the rotifer species and 0.2 ind. ml^–1 for either of the cladoceran species. In all, we had 64 test containers (4 test species of zooplankton × 2 test species of algae × 2 algal densities × 4 replicates). We found a significant effect of algal size on the growth rates of all the four tested species of zooplankton. The population growth rates of zooplankton ranged from –0.58 to 0.66 and were significantly higher on diet of S. acutus than of S. quadricauda. Thus, our study confirms that the larger colony size and the formation of spines in S. quadricauda were effective defenses against grazing by both rotifers and smaller sized cladoceran Ceriodaphnia dubia but that larger-bodied Daphnia pulex could exploit both the algal populations equally.     

The biology and phenology of the citrus whitefly, Dialeurodes citri, on citrus in the Coastal Plain of Israel

The citrus whitefly, Dialeurodes citri (Ashmead) (Homoptera: Aleyrodidae) (CWF), is a polyphagous citrus pest, originating in S. E. Asia, which was first discovered in the Western Galilee region of Israel in 1975. The larval instars of CWF secrete honeydew, and the sooty mould fungus, which develops on the honeydew, causes damage to the tree and its fruit. In observations made in Israel between 1987 and 1991 CWF usually completed three generations per year, although a small proportion of the population had two or four generations. From October to April a combination of shortened photoperiod and reduced temperature arrest the development of CWF in the fourth larval instar. The average length of the life cycle from egg to adult emergence was 65 days in the first generation (April–June), 52 days in the second generation (July–August) and 8 months in the third generation (September–April). Under laboratory conditions of L16: D8 and 25 °C, the mean developmental time was 54 days, and the duration of the egg, first larval instar, second larval instar, third larval instar, fourth larval instar and putative pupa (red eyes) were 12.1, 6.5, 5.5, 7.6, 18, and 4.7 days, respectively. Adults prefer to lay their eggs on young, fully developed citrus leaves, but also oviposit on older leaves. The inner region and shaded sides of the tree are preferred for oviposition.     

Kinorhyncha from the stomach of the shrimp Pleoticus muelleri (Bate, 1888) from Comodoro Rivadavia, Argentina

Six kinorhynchs were found in the stomachs of the Argentine red shrimp, Pleoticus mulleri (Bate, 1888) from the Argentine coast of Patagonia. Three new species are described: Condyloderes storchi n. sp., Pycnophyes argentinensis n. sp. and P. neuhausi n. sp. A fourth species, Kinorhynchus anomalus Lang, 1953 was previously known only from the coast of Chile. This is the third known record of kinorhynchs documented as a food source. Condyloderes storchi, n. sp. is the fourth new species in this genus. It is distinguished by its paradorsal cuspidate spines on segments 7 and 9, lateral accessory and ventrolateral spines on segments 3, 6, 7, 10 and 11. P. argentinensis, n. sp. has nearly equal sternal width for segments 3–11 (about 7% of the trunk length), episternal plates with three distinct areas along the anterior margin, mid-sternal plate with even margin, mid-dorsal spinose protrusions along the terminal borders of segments 11 and 12, and lateral terminal spines 176 μm long, about 21% of trunk length. P. neuhausi, n. sp.has a prominent posterior elongation of the tergal plate of segment 3, uneven lateral margins of the mid-sternal plate, a maximum sternal width at segment 3, no mid-dorsal spinose processes and mid-ventral thickenings on segments 10–12.     

Ontogenetic shifts in the functional response and interference interactions of Rhyacophila dorsalis larvae (Trichoptera)

1. Ontogenetic shifts in predator behaviour can affect the assessment of food‐web structure and the development of predator–prey models. Therefore, it is important to establish if the functional response and interference interactions differ between life‐stages. These hypotheses were tested by (i) comparing the functional response of second, third, fourth and fifth larval instars of Rhyacophila dorsalis, using three stream tanks with one Rhyacophila larva per tank and one of 10 prey densities between 20 and 200 larvae of Chironomus sp.; (ii) using other experiments to assess interference within instars (two to five larvae of the same instar per tank), and between pairs of different instars (one, two or three larvae per instar; total predator densities of two, four or six larvae per tank). 2. The first hypothesis was supported. The number of prey eaten by each instar increased with prey density, the relationship being described by a type II model. The curvilinear response was stronger for fourth and fifth instars than for second and third instars. Mean handling time did not change significantly with prey density, and increased with decreasing instar number from 169 s for fifth instars to 200 s for second instars. Attack rate decreased progressively with decreasing instar number. Handling time varied considerably for each predator–prey encounter, but was normally distributed for each predator instar. Variations in attack rate and handling time were related to differences in activity between instars, fourth and fifth instars being more active and aggressive than second and third instars, and having a higher food intake. 3. The second hypothesis was partially supported. In the interference experiments between larvae of the same instar or different instars, mean handling time did not change significantly with increasing predator density, and attack rate did not change for second and third instars but decreased curvilinearly for fourth and fifth instars. Interference between some instars could not be studied because insufficient second instars were available at the same time as fourth and fifth instars, and most third instars were eaten by fourth and fifth instars in the experiments. Prey capture always decreased with decreasing attack rate. Therefore, interference reduced prey consumption in fourth and fifth instars, but not in second and third instars. The varying feeding responses of different instars should be taken into account when assessing their role in predator–prey relationships in the field.     

ApoE4 delays dendritic spine formation during neuron development and accelerates loss of mature spines in?vitro

The ε4 allele of the gene that encodes apolipoprotein E (APOE4) is the greatest genetic risk factor for Alzheimer''s disease (AD), while APOE2 reduces AD risk, compared to APOE3. The mechanism(s) underlying the effects of APOE on AD pathology remains unclear. In vivo, dendritic spine density is lower in APOE4-targeted replacement (APOE-TR) mice compared with APOE2- and APOE3-TR mice. To investigate whether this apoE4-induced decrease in spine density results from alterations in the formation or the loss of dendritic spines, the effects of neuron age and apoE isoform on the total number and subclasses of spines were examined in long-term wild-type neurons co-cultured with glia from APOE2-, APOE3- and APOE4-TR mice. Dendritic spine density and maturation were evaluated by immunocytochemistry via the presence of drebrin (an actin-binding protein) with GluN1 (NMDA receptor subunit) and GluA2 (AMPA receptor subunit) clusters. ApoE isoform effects were analyzed via a method previously established that identifies phases of spine formation (day-in-vitro, DIV10–18), maintenance (DIV18–21) and loss (DIV21–26). In the formation phase, apoE4 delayed total spine formation. During the maintenance phase, the density of GluN1+GluA2 spines did not change with apoE2, while the density of these spines decreased with apoE4 compared to apoE3, primarily due to the loss of GluA2 in spines. During the loss phase, total spine density was lower in neurons with apoE4 compared to apoE3. Thus, apoE4 delays total spine formation and may induce early synaptic dysfunction via impaired regulation of GluA2 in spines.     

Predation on Ceriodaphnia cornuta and Brachionus calyciflorus by two Mesocyclops species coexisting in Barra Bonita reservoir (SP,Brazil)

Feeding experiments with two species of carnivorous copepod, Mesocyclops longisetus (Thiebaud) and Mesocyclops kieferi Van de Velde from Barra Bonita, a eutrophic reservoir in São Paulo, Brasil, were performed using two common types of prey: Ceriodaphnia cornuta, a cladoceran, with a mean body length of 464 µm (including spines) or 393 µm (without spines), and Brachionus calyciflorus, a rotifer with a mean body length of 350 µm (including spines) or 279 µm (without spines).Both species showed higher consumption rates on Brachionus than on Ceriodaphnia. For Mesocyclops longisetus, the average rates were: 2.19 prey ind^–1 h^–1 (Brachionus), and 1.30 prey ind^–1 h^–1 (Ceriodaphnia). For Mesocyclops kieferi, the rates were 1.85 prey ind^–1 h^–1 (Brachionus) and 0.60 prey ind^–1 h^–1 (Ceriodaphnia). These experimental data are discussed with reference to the dynamics of the predator and prey populations in the reservoir.Laboratorio de Limnologia, Departamento de Ciencias Biologicas, Universidade Federal de São CarlosCentro de Recursos Hidricos e Ecologia Aplicada Lab. de Limnologia, Departamento de Hidraulica e Saneamento, Escola de Engenharia de São Carlos, Universidade de São Paulo     

Temporal and spatial variation of mortality in field populations of Danaus plexippus L. and D. chrysippus L. Larvae (Lepidoptera: Nymphalidae)

Summary Mortality estimates for the immature stages of two butterfly species, Danaus plexippus and D. chrysippus, were obtained by observing the survival of egg cohorts on different sized patches of food plants (Asclepias spp.), over a one-year period. Losses were variable (0–100%) but usually high (90% and over) throughout the year for both species. Most of the losses in both species occurred in the early stages. The mortality by the third instar accounts for 86–100% of the total losses by instar V. Accordingly both species fall into Price's (1975) type A survivorship category. The size of patches of host plants affected losses. The trend was for increasing losses with increasing patch size. A full life-budget is presented for D. plexippus and implications of the observed mortality levels for competition between the two butterfly species is discussed.     

Effect of KK-42 on growth,development, molting,and metamorphosis of the european corn borer,Ostrinia nubilalis (Hübner)

KK-42 (1-benzyl-5-[(E)-2,6-dimethyl-1,5-heptadienyl]imidazole), administered by feeding, delayed the growth and development of nondiapause-bound and diapause-bound Ostrinia nubilalis larvae and increased the length of the instar. At doses of 80–240 ppm, 62–100% of nondiapause-bound fourth instars precociously pupated or remained as fourth instars, while 52–100% of diapause-bound fourth instars did not molt to the fifth instar. Injection of these nondiapause- and diapause-bound KK-42-fed fourth instars with ecdysone elicited a molt and resulted in the production of larval-pupal intermediates. When mature fourth instar controls were similarly injected, they molted into normal fifth instars. These results support the view that KK-42 delays/inhibits ecdysteroid production. Both eupyrene and apyrene spermiogenesis were prematurely initiated in nondiapause-bound fourth instars that were fed on medium containing 160 ppm KK-42. Fenoxycarb, a potent juvenile hormone mimic, rescued nondiapause-bound fourth instars from precocious pupation. All fenoxycarbtreated larvae either molted to the fifth instar or remained as fourth instars and eventually died. These results support the view that treatment with KK-42 inhibits JH production. When KK-42 treatment was begun in the third instar, a considerable number of nondiapause-bound and some diapause-bound third instars precociously molted to the fifth instar. There was a correlation between weight and the incidence of precocious molting in that third instars destined to skip the fourth instar attained a weight, as pharate fifth instars, of two to three times more than pharate fourth instar controls. Similarly, fourth instars that were destined to undergo precocious pupation attained a weight, as pharate pupae, that was approximately two times more than pharate fifth instar controls. More potent analogues of KK-42 may prove useful in controlling populations of 0. nubilalis by interfering with their growth, development, and metamorphosis. © 1995 Witey-Liss, Inc.

1 This article is a US Government work and, as such, is, in the public domain in the United States of America.