Factors affecting male Prays oleae (Lepidoptera: Yponomeutidae) captures in pheromone-baited traps in olive orchards

Effects of trap design, height and side of trap placement on olive trees, pheromone doses in dispensers, aging of dispensers in the field, and secondary pheromone components were evaluated for the development of an effective pheromone monitoring system for Prays oleae (Bernard) Lesne (Lepidoptera: Yponomeutidae) in olive orchards. Field trials showed that trap design, pheromone dose, and trapping side affected male captures, whereas dispenser age, trap height, and secondary components had no influence. Pherocon 1C and Delta traps baited with 1 mg of (Z)-7-tetradecenal captured more male moths than Pherocon II or Funnel traps. Placement of traps at different cardinal directions significantly affected captures, but this trend was not consistent and varied with flight period and trap position internal or external to the tree canopy. Moth phenology as determined by pheromone traps from early April to mid-October was consistent with published field data. Results indicate that Pherocon 1C or Delta traps baited with 1 mg of (Z)-7-tetradecenal provide an effective tool for monitoring the flight activity of P. oleae and the time of application of control measures.     

Bionomics of Prays citri (Lepidoptera: Yponomeutidae) and their use in a model of control by male mass trapping*

Abstract. 1. The paper describes the population dynamics of Prays citri (Milliere), relevant to the control of this pest by synthetic pheromone, as well as infestation of lemon trees in various areas and seasons. 2. The responses of males to natural and synthetic sex pheromones are compared, and ratios for the degree of attraction of traps compared with the degree of attraction of competing wild females are calculated. 3. The ratios obtained with various population densities over two seasons of the pest's activity are presented. 4. The data are used in a model simulating control of Prays citri by male mass trapping.     

Management of Prays citri in lemon orchards by mass trapping of males

Preliminary field trials on the control of Prays citri (Millière) (Lepidoptera: Yponomeutidae) by mass trapping were carried out from 1976 using synthetic sex pheromone (Z-7-tetradecenal) baited traps. A clear tendency was revealed for a reduction in flower infestation by the larvae of this pest, providing that the minimum required number of traps (120 per ha) were employed and maintained throughout the entire year. In 1980–1983, commercial field trials were conducted over 30 ha of lemon trees. Rubber septa dispensers were loaded with 0.5–0.6 mg synthetic pheromone and refilled every four months. For comparison, about 30 ha lemon trees were sprayed 3–6 times a year with an organophosphate (azinphos-methyl) insecticide treatment. One plot of 0.22 ha was used as control. Results from all three areas were compared for mean male catch per trap per day, mean number of moths emerging per flower, and fruit yield for the two years prior to the trials and the three years of the trials in all plots. Lemon trees without control measures showed a decline in fruit yield. Controlling the moth by mass trapping of males, was significantly (P<0.05) cheaper and somewhat more efficient than spraying 3–6 times/year with insecticides.

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Résumé Des essais préliminaires de lutte contre P. citri Millière (Lep. Yponomeutidae) par piégeage de masse ont été menés en 1976 en utilisant la phéromone sexuelle (Z-7-tétradécénal) comme appât. On a observé une nette tendance à la réduction de l'infestation des fleurs par les chenilles a été observée lorsque le nombre nécessaire de pièges (120/ha) a été maintenu toute l'année. En 1980–83 des essais commerciaux ont été réalisés sur un verger de 30 ha de citronniers. Des diffuseurs rubber septa étaient remplis avec 0,5–0,8 mg phéromones synthétiques et rechargés tous les 4 mois. Par comparaison, un verger de 30 ha a été pulvérisé 3 à 6 fois par an avec un organophosphate (méthyle d'Azinphos). Le témoin était constitué par une parcelle de 0,22 ha. Les captures moyennes quotidiennes de mâles par piège, le nombre de papillons obtenus par fleur e les récoltes de fruits pendant les 2 années précédant ces interventions et les 3 années de durée des traitements ont permis de comparer la situation sur les 3 aires. Les citronniers témoins ont présenté une diminution de production de fruits. La protection par le piégeage massif des mâles est significativement moins chère (P<0,05) et semble plus efficace que 3 à 6 traitements insecticides par an.

     

Influence of within-orchard trap placement on catch of codling moth (Lepidoptera: Tortricidae) in sex pheromone-treated orchards

The influence of trap placement on catches of codling moth, Cydia pomonella L., was examined in a series of studies conducted in orchards treated with Isomate-C Plus sex pheromone dispensers. Mark-recapture tests with sterilized moths released along the interface of pairs of treated and untreated apple and pear plots found that significantly more male but not female moths were recaptured on interception traps placed in the treated plots. In a second test, significantly higher numbers of wild male and female moths were caught on interception traps placed in treated versus untreated plots within a heavily infested orchard. The highest numbers of male moths were caught on traps placed along the interior edge of the treated plots. Trap position had no influence on the captures of female moths. In a third test, north-south transects of sex pheromone-baited traps were placed through adjacent treated and untreated plots that received a uniform release of sterilized moths. Traps on the upwind edge of the treated plots caught similar numbers of moths as traps upwind from the treated plots. Moth catch was significantly reduced at all other locations inside versus outside of the treated plots, including traps placed on the downwind edge of the treated plot. In a fourth test, five apple orchards were monitored with groups of sex pheromone-baited traps placed either on the border or at three distances inside the orchards. The highest moth counts were in traps placed at the border, and the lowest moth counts were in traps placed 30 and 50 m from the border. In a fifth test, the proportion of traps failing to catch any moths despite the occurrence of local fruit injury was significantly higher in traps placed 50 versus 25 m from the border. The implications provided by these data for designing an effective monitoring program for codling moth in sex pheromone-treated orchards are discussed.     

In vitro Metabolism of Flupyrazofos to Plutella xylostella (Lepidoptera: Yponomeutidae) and Spodoptera exigua (Lepidoptera: Noctuidae)

In vitro metabolism study was conducted to observe the role of enzymes and its kind responsible for tolerance in metabolism of flupyrazofos to Diamond backmoth (DBM), Plutella xylostella as a susceptible insect and Beet armyworm (BAW), Spodoptera exigua as a tolerance insect. The results indicated that there were some differences between the DBM (LD₅₀, 0.54 ppm) and BAW (LD₅₀, >2,000 ppm). In the microsomal fractions, the 4th instar BAW larvae metabolized almost the same amount (about 38%) of flupyrazofos with or without NADPH, but it increased the amount of flupyrazol in the 3rd instar larvae of DBM. Flupyrazofos-oxon was slightly increased with the addition of NADPH in both species. With the addition of piperonyl butoxide (PB) or Iprobenfos (IBP), the amount of flupyrazol was decreased to one third of flupyrazol produced by NADPH in BAW and one fourth of flupyrazol produced by NADPH in DBM. Some effects of inhibitors, PB and IBP, and co-factor, NADPH, were showed when flupyrazofos was metabolized with or without them. This means that esterase and oxidase are responsible for the tolerance mechanism of flupyrazofos in DBM and BAW.     

Volumes of petroleum spray oil required for control of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in mature citrus orchards

Studies on the relationship between volume of spray and suppression of citrus leafminer ( Phyllocnistis citrella ) oviposition by petroleum spray oil on 4 m-high mature orange trees showed a negative exponential relationship between spray volume and the number of mines per leaf. Significant reductions in the number of mines per leaf compared to unsprayed trees was achieved at spray volumes of ≥ 3300 L/ha using oscillating boom and at ≥ 3200 L/ha using rotary atomiser sprayers. However, improvements in efficacy at volumes over 3200–3300 L/ha were not significant and so of little practical value. The optimal spray volumes for citrus leafminer control are therefore suggested to be 3000–3500 L/ha. No significant difference in effectiveness was found between the oscillating boom at 3300 L/ha and a rotary atomiser at 3200 L/ha. The effect of oil spray on the citrus leafminer parasitoid Semielacher petiolatus (Girault) (Hymenoptera: Eulophidae) was inconsistent. Improved droplet deposition and coalescence may enhance the coverage of new growths and increase the efficacy of oil spray for protection of plants from oviposition.     

Influence of ground cover management on diversity and density of phytoseiid mites (Acari: Phytoseiidae) in Guadeloupean citrus orchards

The abundance and diversity of phytoseiid mites in the vegetal ground cover of a citrus orchard were surveyed by monthly samplings from October 2008 to July 2009. Six different vegetal cover management methods were studied: herbicide application without mowing (Gly), mowing without herbicide application (PV), mowing with herbicide application (AV), late mowing without herbicide application (LMV), cover crop (Neonotonia wightii, Fabaceae) without herbicide application (PNeo) and cover crop with herbicide application (ANeo). Eleven species were present in the ground cover, with Phytoseius rex and Proprioseiopsis mexicanus as major species. Species richness and densities (1.5 ± 4.5) in the Gly treatment were very low, except for one sample 4 months after herbicide treatment. The AV and PV treatments showed poor diversity and very low mite densities (1.2 ± 2.6 and 1.4 ± 1.5, respectively). The LMV treatment showed the highest diversity and high density of phytoseiid mites (6.9 ± 8.8). The ANeo and PNeo treatments also showed generally high diversity, but with variations in time and exhibited the highest density of phytoseiid mites (13.5 ± 12.7 and 13.4 ± 9.1, respectively). Neonotonia wightii as the cover crop seems to act as a reservoir of phytoseiid mites, sustaining abundant and diverse populations all year round. Some naturally occurring plant species such as Achyranthes aspera, Amaranthus dubius and Eleutheranthera ruderalis could also constitute favourable host plants for Phytoseiidae. Results are discussed in relation to the potential of collected phytoseiid species as candidates for biological control of phytophagous mites on Guadeloupean citrus orchards.     

Effect of trap type, trap color, trapping location, and pheromone dispenser on captures of male Palpita unionalis (Lepidoptera: Pyralidae)

Field studies were conducted to evaluate the influence of trap design, trapping location, type of pheromone dispenser, and trap color on the capture of Palpita unionalis (Hübner) males, in olive groves. The experiments were carried out in two regions, Alexandria (northern Greece) and Oropos (central Greece), where olives are cultivated. In both regions, the majority of the males (> 70% of the total) were caught from late autumn to early winter, whereas < 1% was caught during July and August. Among the trap types used, the Funnel was significantly more attractive than Delta, Pherocon 1C, and Pherocon II traps. More males were caught in traps placed at the periphery of the groves than those placed in the center. Among the four colored traps tested, white traps were the most effective. However, a significant difference in trap catches was found between white and brown traps. Traps baited with red rubber septa captured more males than those baited with the white one. The use of these parameters in monitoring and managing P. unionalis is discussed.     

Photoperiodism and seasonality in neotropical population of Plutella xylostella L. (Lepidoptera: Yponomeutidae)

Neotropical populations of the diamondback moth Plutella xylostella L. have seasonal cycles of growth and decrease, and moth migration plays a fundamental role in generating such population dynamics. Since the oscillation of these populations is predictable, photoperiod might operate as a signal that triggers the migratory behaviour of the insect. Migration in insects is usually preceded by reproductive diapause, a photoperiodic response that can be characterised by morphological, physiological and behavioural alterations that permit to discriminate between migratory and non-migratory forms. In this study, I tested whether the pre-imaginal and reproductive development of P. xylostella from Minas Gerais (Brazil) is affected by artificial day-lengths that are equivalent to the periods of natural population growth or decrease. No evidence of photoperiodic response was found for the insect reared in laboratory on five different constant photoperiods, from 8h to 16h of light per day. There was no significant variation in survival and duration of egg, larva, and pupa stages or in pupal weight, adult size (forewing length), fecundity, and longevity. Although some species have geographically distinct photoperiodic responses, previous assumptions that cosmopolitan P. xylostella responds to photoperiod in temperate regions was questioned. Migratory and population seasonality among neotropical populations of P. xylostella certainly occurs independently of the photoperiodic announcement of seasonal changes in habitat quality.     

Interactions between plant odours and pheromone reception in small ermine moths (Lepidoptera: Yponomeutidae)

Interactions between plant odours and pheromone reception werestudied in small ermine moths (Yponomeuta spp.) with electroantennogramand single cell recordings, both separately and simultaneously.The results verified that interactions do indeed occur at thereceptor level. It is suggested that, in the reproductive isolationof these moths, plant odours may play both a direct role throughplant odour receptors and an indirect role via modulation ofpheromone receptors.     

Phenology of Lacanobia subjuncta (Lepidoptera: Noctuidae) in Washington and Oregon apple orchards

The phenology of Lacanobia subjuncta (Grote & Robinson) (Lepidoptera: Noctuidae) was investigated in 30 apple orchards in central Washington state and northeastern Oregon from 1998 to 2001 (57 total orchard-yr). Adult captures in pheromone-baited traps were fit to a Weibull distribution to model emergence of the first and second generations. Initial capture of first generation adults was observed at 216.2 +/- 2.6 degree-days (DD) (mean +/- SEM) from 1 March by using a base temperature of 6.7 degrees C. The model predicted that flight was 5 and 95% complete by 240 and 700 degree-days (DD), respectively. Monitoring of oviposition and hatch was used to establish a protandry plus preoviposition degree-day requirement of 160.0 +/- 7.7 DD, as well as to provide data to describe the entire hatch period. Egg hatch was 5 and 95% complete by 395 and 630 DD, respectively. The start of the second flight was observed at 1217.1 +/- 8.3 DD by using an upper threshold for development of 32 degrees C and a horizontal cutoff. The model indicated that the second flight was 5 and 95% complete by 1220 and 1690 DD, respectively. Second generation hatch was 5 and 95% complete by 1440 and 1740 DD, respectively. A discussion of the potential uses of these detailed phenology data in optimizing management strategies is presented.     

Biochemical Characterization of C-type Lectin in the Diamondback Moth,Plutella xylostella (Yponomeutidae: Lepidoptera)

Lectins due to their affinity to carbohydrate moiety are involved in diverse functions like cell attachment in embryogenesis, organogenesis and cellular trafficking as well as nonself recognition in immune responses. Agglutinating activity was detectable in Plutella xylostella (Yponomeutidae: Lepidoptera) against 14 different species including bacterial and yeast cells, among which the whole body homogenate of P. xylostella agglutinated Providencia vermicola, Flavobacterium sp., and Saccharomyces cerevisiae with high titers. On analysis of physico-chemical properties, this putative agglutinating factor (s) was specifically dependent on the presence of Ca⁺⁺ for its activity and was reversibly sensitive to EDTA. The agglutinating activity was stable at pH 6–8, but was heat-labile. The agglutinating factor (s) was proteinaceous in nature as it was completely precipitable by ammonium sulphate. Its carbohydrate binding activity was demonstrated by inhibition assay, which revealed that methyl α-D-mannopyranoside inhibited agglutination against P. vermicola. In contrast, P. xylostella parasitized by an endoparasitoid wasp, Cotesia plutellae (Braconidae: Hymenoptera), also showed the agglutination properties with somewhat higher activity than the nonparasitized. Carbohydrate inhibition assay with methyl α-D-mannopyranoside was detectable at one-fold higher concentration in the homogenate of the parasitized larvae, suggesting that the agglutinating factor (s) is inducible or due to de novo parasitism-specific synthesis. These results suggest the presence of calcium-dependent lectin in P. xylostella and an alteration in the agglutinating property by C. plutellae parasitization.     

Impact of Embryonopsis halticella eaton larvae (Lepidoptera: Yponomeutidae) feeding in Marion Island tussock grassland

Summary Embryonopsis halticella is a brachypterous moth endemic to the Kerguelen Province of sub-Antarctic islands. Its larvae are strictly host-specific grass-borers of the tussock grass Poa cookii, and are the major herbivores on Marion Island. Monthly sampling over one year (1984) on Marion Island showed that E. halticella larvae reach a biomass of 0.222 g m^-2 (dry mass) in P. cookii grassland in summer. In feeding experiments conducted in the laboratory on Marion Island, larvae consumed 0.3 X their own live mass in leaf material daily. Extrapolated consumption rates in the field range from 1 kg ha^-1 month^-1 in winter to 18 kg ha^-1 month^-1 (dry mass) in summer. Total annual consumption, based on leaf feeding only, amounts to 86 kg ha^-1 (dry mass). Significant shifts in diet from foliage to seeds occur during spring, and larvae also consume their own frass and exuviae. It is calculated that E. halticella larvae remove 2.5% of the annual production of Poa cookii in Marion Island tussock grassland.     

Behavioural responses of two small ermine moth species (Lepidoptera: Yponomeutidae) to plant constituents

On the basis of electrophysiological screening of lateral and medial styloconic sensilla of caterpillars of Yponomeuta species, several hypotheses concerning behavioural effects of plant constituents can be posed (Van Drongelen, 1979). Feeding experiments have been carried out with intact larvae of Y. cagnagellus (Hb.) and Y. evonymellus (L.). Both species display neural responses to dulcitol, phloridzin and prunasin. Leaf discs of the host plants of these species were modified using these three constituents and effects were studied in choice and non-choice situations. Dulcitol appears to stimulate food intake of both species, whereas phloridzin acts as a deterrent exclusively in a choice situation. Prunasin inhibits feeding of Y. cagnagellus in a choice situation, but Y. evonymellus does not show a reaction to this compound at the concentration applied. Neural mechanisms probably underlying these behaviours are discussed.

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Zusammenfassung Aufgrund elektrophysiologischer Versuche mit lateralen und medialen Sensilla styloconica von Yponomeuta-Arten können mehrere Hypothesen über Verhaltenseffekte von Pflanzenbestandteilen aufgestellt werden (Van Drongelen, 1979). Y. cagnagellus und Y. evonymellus zeigen neurale Reaktionen auf Dulcitol, Phlorizin und Prunasin.Es wurden Frassexperimente mit intakten Raupen beider Arten durchgeführt. Blattscheiben der Wirtspflanzen wurden mit den genannten Stoffen modifiziert, und die Effekte wurden in Wahl- und Nichtwahlversuchen studiert. Dulcitol scheint die Futteraufnahme beider Arten anzuregen, während Phlorizin als Abhaltestoff wirkt und zwar nur in einer Wahlsituation. Prunasin verhindert Fressen bei Y. cagnanellus in einer Wahlsituation, während Y. evonymellus auf diesen Stoff in der geprüften Konzentration nicht reagiert. Neurale Mechanismen, welche wahrscheinlich diesem Verhalten zugrunde liegen, werden diskutiert.

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Supported by the Foundation for Fundamental Biological Research (BION), subsidized by the Netherlands Organization for the Advancement of Pure Research (ZWO).     

Dispersion patterns of Diachasmimorpha longicaudata (Hymenoptera: Braconidae) in citrus orchards in southeast Brazil

We studied the dispersion patterns of the exotic endoparasitoid, Diachasmimorpha longicaudata (Ahsmed) (Hymenoptera: Braconidae), in 1999 (summer) and in 2000 (winter) in a citrus orchard in southeast Brazil. Different population densities of D. longicaudata were released in the centre of the orchard, and their dispersion was determined by using yellow, sticky, rectangular traps, placed in various distances and heights around the release point. Our results suggest that during summer, climatic conditions did not affect dispersion. However, in winter, dispersion rates were positively affected by temperature, and negatively by rainfall. Both estimated dispersal distance and surface were higher in summer than in winter for all release densities. Dispersion peaked at 2000 parasitoids ha^?1 in summer and 8000 parasitoids ha^?1 in winter. The importance of our results for the biological control of fruit flies by augmented or innoculative releases of D. longicaudata in southeast Brazil is discussed.     

不同色板对柑橘园蓟马的诱集效果及蓝板的诱捕效果

通过对黄色、蓝色、深蓝色、白色、红色、绿色、紫色、灰色、黑色和粉红色10种不同颜色色板对柑橘园蓟马的诱集效果的比较试验表明,柑橘园蓟马对蓝色和深蓝色色板趋性最大,与其它8种颜色色板之间有着极显著差异(P<0.01)。蓝色色板对蓟马在东南西北4个不同方位中的诱捕作用研究表明,南面方位诱集的蓟马数量最多,与西、北两个方位之间有着显著差异(P<0.05)。当平均株高为220cm时,挂板高度分别为60、120、180和240cm,高度为120cm时诱集的蓟马数量最多,与其它3个高度之间存在显著差异。色板间距分别为2、3、4和5m时,结果表明间距为4m和5m时每板诱集的蓟马数量较多,与其它间距之间有着显著差异。从上午8点到下午6点每间隔2h的5个时间段中,各时间段之间没有显著差异。在蓝色色板的小区防治试验中,在挂板3、6和12d后,诱捕效果分别达到41.5%,53.9%和37.7%。     

Parasitism of obliquebanded leafroller (Lepidoptera: Tortricidae) in commercially managed Michigan apple orchards

The obliquebanded leafroller, Choristoneura rosaceana (Harris), is one of the major arthropod pests of apple in the United States. In 1999 and 2000, a survey of the obliquebanded leafroller parasitoid complex in commercially managed apple orchards in Michigan's two largest fruit production regions was conducted to determine the species present and their importance to obliquebanded leafroller population management. In total, 8,961 obliquebanded leafroller larvae were collected of which 2,174 were parasitized. Parasitism increased from the overwintering generation to the summer generation for both regions and both years. In 1999, 11% of the 1,126 overwintering obliquebanded leafrollers collected were parasitized, whereas 28% of the 3,669 summer generation were parasitized. In 2000, 8% of the 489 overwintering obliquebanded leafrollers collected were parasitized, whereas 26% of the 3,677 summer generation obliquebanded leafrollers collected were parasitized. In total, 20 species of hymenopteran and dipteran parasitoids from seven families were recovered from obliquebanded leafroller larvae over the course of the study. The most abundant hymenopteran parasitoids were Bassus dimidiator Nees (Braconidae) comprising 48% of the total parasitoids, followed by Colpoclypeus florus (Walker) (Eulophidae) (8% of the total) and Macrocentrus linearis (Nees) (Braconidae) (2% of the total). Dipteran parasitoids (Tachinidae) accounted for 36% of the parasitism and were largely comprised of Nilea erecta (Coquillett) (5%) and Actia interrupta Curran (13%). These collections represent new host records for B. dimidiator, Bassus annulipes (Cresson) Hyphantrophaga blanda (Osten Sacken), and Compsilura concinnata (Meigen). The parasitoid C. florus is also reported from Michigan for the first time.     

Genetic differentiation among various populations of the diamondback moth, Plutella xylostella (Lepidoptera: Yponomeutidae)

Genetic variation among 14 populations of Plutella xylostella (Linnaeus) from USA (Geneva, New York), Brazil (Brasilia), Japan (Okayama), The Philippines (Caragan de Oyo), Uzbekistan (Tashkent), France (Montpellier), Benin (Cotonou), South Africa (Johannesburg), Réunion Island (Montvert), and five localities in Australia (Adelaide, Brisbane, Mareeba, Melbourne, Sydney) were assessed by analysis of allozyme frequencies at seven polymorphic loci. Most of the populations were not in Hardy-Weinberg equilibrium and had a deficit in heterozygotes. The global differentiation among populations was estimated by the fixation index (Fst) at 0.103 for the 14 populations and at 0.047 when populations from Australia and Japan, which differed most and had a strong genetic structure, were excluded from the analysis. By contrast, the populations from Benin (West Africa) and Brazil (South America) were very similar to each other. Genetic differentiation among the populations was not correlated with geographical distance.     

Instar-specific phenology of Pandemis pyrusana and Choristoneura rosaceana (Lepidoptera: Tortricidae) in Washington apple orchards

Head capsule width was used to determine the instar specific phenology of the leafroller Pandemis pyrusana Kearfott and the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), attacking apple in Washington state during 2001-2003. In total, 7012 P. pyrusana and 6122 obliquebanded leafroller larvae were measured from apple orchards from mid-March to mid-September. Degree-day accumulations from each site were paired with the head capsule data to determine the periods during which different instars were present in the field. The implications of this work for pest management and biological control of leafrollers is discussed.