Articles by Stefanos S Andreadis
The high-dose/refuge strategy is considered as the main strategy for delaying resistance in targe... more The high-dose/refuge strategy is considered as the main strategy for delaying resistance in target pests to genetically modiÞed crops that produce insecticidal proteins derived from Bacillus thuringiensis Berliner. This strategy is based on a key assumption that resistance alleles are initially rare (10 3). To test this assumption, we used an F 2 screen on natural populations of Sesamia nonagrioides
Discoloration of the leaves of unhealthy pomegranate trees, caused by the Coleopteran species Amp... more Discoloration of the leaves of unhealthy pomegranate trees, caused by the Coleopteran species Amphicerus bimaculatus (Olivier, 1790), was found in a newly planted pomegranate orchard in April 2011 in northern Greece (Vrontou area). Identification of the species was based on morphological characteristics. This report is the first record of A. bimaculatus in Greece infesting pomegranate trees.
Lycoriella ingenua Dufour (Diptera: Sciaridae) is acknowledged as the major pest species of the w... more Lycoriella ingenua Dufour (Diptera: Sciaridae) is acknowledged as the major pest species of the white button mushroom, Agaricus bisporus, throughout the world. Components of the female-produced sex pheromone of this species were identified previously as C15-C18 n-alkanes, with the major component n-heptadecane, and shown to be attrac- tive to L. mali. However, a subsequent report could not repeat this work. We reinvestigated the sex pheromone of this species by confirming that virgin females were attractive to males in a Y-tube bioassay and by collection of extracts from virgin fe- males. Extracts were analyzed by gas chromatography coupled to electroantennographic detection, and by the less widely-used technique of gas chromatography coupled to a behavioral bioassay to detect compounds causing wing- fanning and copulatory abdomen curling in males. A single, behaviorally-active pheromone component was isolated and characterized by gas chromatography coupled to mass spec- trometry. This component was definitively not n-heptadecane or any of the other C15-C19 n-alkanes reported previously, but is proposed to be a sesquiterpene alcohol having analytical characteristics that closely matched those of reference germacradienols.
Associations between yeasts and insect herbivores are widespread, and these inter-kingdom interac... more Associations between yeasts and insect herbivores are widespread, and these inter-kingdom interactions play a crucial role in yeast and insect ecology and evolution. We report a survey of insect attraction to live yeast from a community ecology perspective. In the summer of 2013 we screened live yeast cultures of Metschnikowia pulcherrima, M. andauensis, M. hawaiiensis, M. lopburiensis, and Cryptococcus tephrensis in an organic apple orchard. More than 3000 arthropods from 3 classes, 15 orders, and 93 species were trapped; ca. 79% of the trapped specimens were dipterans, of which 43% were hoverflies (Syrphidae), followed by Sarcophagidae, Phoridae, Lauxaniidae, Cecidomyidae, Drosophilidae, and Chironomidae. Traps baited with M. pulcherrima, M. andauensis, and C. tephrensis captured typically 2.4 times more specimens than control traps; traps baited with M. pulcherrima, M. hawaiiensis, M. andauensis, M. lopburiensis, and C. tephrensis were more species-rich than unbaited control traps. We conclude that traps baited with live yeasts of the genera Metschnikowia and Cryprococcus are effective attractants and therefore of potential value for pest control. Yeast-based monitoring or attract-and-kill techniques could target pest insects or enhance the assemblage of beneficial insects. Manipulation of insect behavior through live yeast cultures should be further explored for the development of novel plant protection techniques.
On examination of the wound of a patient who was treated previously with external fixation for a ... more On examination of the wound of a patient who was treated previously with external fixation for a diaphysial fracture of the femur, we observed the presence of multiple living larvae (maggots) of dipterous flies. Treatment included removal of the maggots and use of antibiotic. The importance of hygiene and sanitation is discussed.
The effect of temperature on the biology of Venturia canescens (Gravenhorst) (Hymenoptera: Ichneu... more The effect of temperature on the biology of Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) is well understood under constant temperature conditions, but less so under more natural, fluctuating conditions. Herein we studied the influence of fluctuating temperatures on biological parameters of V. canescens. Parasitized fifth-instar larvae of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) were reared individually in incubators at six fluctuating temperature regimes (15-19.5 oC with a mean of 17.6 oC, 17.5-22.5 oC with a mean of 19.8 oC, 20-30 oC with a mean of 22.7 oC, 22.5-27.5 oC with a mean of 25 oC, 25.5-32.5 oC with a mean of 28.3 oC and 28.5-33 oC with a mean of 30 oC) until emergence and death of V. canescens adults. Developmental time from parasitism to adult eclosion, adult longevity and survival were recorded at each fluctuating temperature regime. In principle, developmental time decreased with an increase of the mean temperature of the fluctuating temperature regime. Upper and lower threshold temperatures for total development were estimated at 34.9 and 6.7 oC, respectively. Optimum temperature for development and thermal constant were 28.6 oC and 526.3 degree days, respectively. Adult longevity was also affected by fluctuating temperature, as it was significantly reduced at the highest mean temperature (7.0 days at 30 oC) compared to the lowest one (29.4 days at 17.6 oC). Survival was low at all tested fluctuating temperatures, apart from mean fluctuating temperature of 25 οC (37%). Understanding the thermal biology of V. canescens under more natural conditions is of critical importance in applied contexts. Thus, predictions of biological responses to fluctuating temperatures may be used in population forecasting models which potentially influence decision-making in IPM programs.
The fumigant activity of essential oil vapors distilled from sweet basil Ocimum basilicum
L. and... more The fumigant activity of essential oil vapors distilled from sweet basil Ocimum basilicum
L. and spearmint Mentha spicata L. (Lamiaceae) were tested against two major stored products pests
Ephestia kuehniella (Zeller) and Plodia interpunctella (Hu¨ bner) (Lepidoptera: Pyralidae). Various oil
doses (0.5, 2.5, 5, 50, 250, 500, 1,000, and 1,500 ml/liter air), for an exposure period of 24 h, were tested.
The essential oils were subjected to gas chromatography–mass spectrometry analysis and revealed that
the major compounds were for spearmint oil carvone (67.1%) and limonene (þ1,8 cineole; 14.3%) and
for basil oil linalool (45.9%), 1,8 cineole (16.7%) and eugenol (10.3%). Apart from a few exceptions, no
significant differences in insecticidal action were observed between basil and spearmint oil. Both oils
were highly effective against adult moths, given that notable mortality (>80%) was recorded after exposure
to low doses such as 2.5 ml/liter. Noteworthy, egg mortality was also recorded, reaching 73–79% for
basil and 56–60% for spearmint. Toxicity data indicated that larvae and pupae were the most tolerant
stages in all cases. Larval mortality never exceeded 21 and 18%, for basil and spearmint, respectively, irrespective
of moth species. Basil and spearmint oils displayed mortalities as high as 38 and 28% in pupae.
Lethal doses (LD50 and LD99) values were estimated via probit analysis. Developmental stage proved to
be a significant factor, whereas the effect of oil species on insect mortality was insignificant. With the exception
of adult individuals, basil and spearmint oils did not show satisfactory overall insecticidal activity
against E. kuehniella and P. interpunctella.
The common house mosquito, Culex pipiens
(Diptera: Culicidae), which is considered the primary b... more The common house mosquito, Culex pipiens
(Diptera: Culicidae), which is considered the primary bridge
vector ofWest Nile Virus (WNV) to humans, is a wide spread
insect pest with medical importance and consists of two
distinct bioforms, Cx. pipiens f. pipiens and Cx. pipiens f.
molestus. Here, we consider the adult lifespan of male and
female Cx. pipiens f. pipiens under controlled conditions at
five constant temperature regimes (15, 20, 25, 27.5, and
30 °C). Our results show that adult longevity was affected
by temperature, as it significantly decreased with increase in
temperature. At the highest tested temperature, mean adult
longevity did not exceed 12 days for both sexes and thus
makes impossible the risk ofWNV transmission. On the other
hand at the lowest temperature, longevity was extremely high
with some individuals surviving up to 129 and 132 days,
males and females, respectively, and thus enable them to
function as potential vectors of WNV for a prolonged period
of time. As far as sex is concerned, adult females displayed a
1.2–1.4-fold longer longevity compared to the male ones.
However, this difference was significant only at the lowest
and highest tested temperature regime. This information is
useful in determining the critical temperatures which may
affect the distribution of Cx. pipiens and consequently the risk
of WNV transmission. Moreover, the effect of environmental
temperature should be considered when evaluating the abundance
of these species
Identification of the sex pheromone of Cydia splendana (Lepidoptera, Tortricidae) by pheromone gl... more Identification of the sex pheromone of Cydia splendana (Lepidoptera, Tortricidae) by pheromone gland analysis followed by field trapping with synthetic compounds shows the occurrence of two pheromone races. Acorn moth females from Sweden, where oak Quercus robur is the only host plant, use a blend of the E,Z and E,E isomers of 8,10-dodecadien-1-yl acetate. In Central and Southern Europe, where C. splendana feeds on chestnut Castanea sativa and several species of oak, males respond to another isomer blend, E,E and Z,E. The distribution of the two pheromone races of C. splendana overlaps in Northern France, where they share oak as plant host. Differences in sex communication signals lead to behavioural pre-mating isolation between these populations, and emphasize the role of specific mate recognition in speciation events.
Pest Management Science, 2014
BACKGROUND:Venturia canescens is aparthenogenetic koinobiont endoparasitoidof several pyralidmoth... more BACKGROUND:Venturia canescens is aparthenogenetic koinobiont endoparasitoidof several pyralidmothlarvae that aremajor
pests of stored products. Low temperatures have been extensively used to control stored-product insects as an alternative
to the application of traditional pesticides. However, most studies have focused on the cold hardiness profile of the major
stored-product pests. The objective of this study was to investigate how factors such as age, food, host availability and
acclimation affect the cold tolerance of V. canescens by determining its supercooling capacity.
RESULTS:Youngadults displayed significantly lower supercoolingpoints (SCPs) thanolder adults, irrespective of the availability
of a host. Host availability had a moderate effect on supercooling, whereas food consumption resulted in a significant
enhancement of SCP. Acclimation to low temperatures increased the supercooling capacity considerably. Furthermore, an
increase in the duration of exposure to acclimation temperature resulted in lower SCPs.
CONCLUSION: Adults of V. canescens displayed an enhanced ability to supercool, however, they appear to be less cold tolerant
than their respective hosts. This information would be useful in determining the potential of using V. canescens as a biological
agent in Integrated PestManagement (IPM) programs, taking into consideration the adverse effects of low temperatures on its
survival.
IOBC-WPRS Bulletin 99, 2014
Mosquitoes of the genus Culex are considered as major vectors of many arboviruses that cause huma... more Mosquitoes of the genus Culex are considered as major vectors of many arboviruses that cause human diseases all over the world, such as, West Nile Virus, Japanese encephalitis, St. Louis encephalitis, and Western equine encephalitis. Female Culex mosquitoes form a droplet at the apex of each egg, which affects the oviposition behaviour of intraspecific gravid females. The main volatile compound, present in the apical droplets of the egg rafts, is the (–)-(5R,6S)-6-acetoxy-5-hexadecanolide. The current review article presents the most important approaches that have been developed for the synthesis of the Culex sp. oviposition pheromone. Moreover, we focus on bioassays methods that have been employed under different conditions concerning the use of synthetic Culex sp. oviposition pheromone.
IOBC-WPRS Bulletin 99, 2014
Mating disruption is a worldwide commercially viable pest management technique. In the past 20 ye... more Mating disruption is a worldwide commercially viable pest management technique. In the past 20 years numerous pheromone-mediated mating disruption studies have been applied in Greece, targeting, mainly for lepidopteran pests. The major limitation for the further adoption of mating disruption in Greece is the typical small plot size of agricultural fields, which is less than 5 ha in average. Herein, we review the status of knowledge about mating disruption studies in Greece, based on literature, during a 25-year period (1986-2011). Our data concerns mainly research since commercial use of MD is not published. According to our knowledge, commercial use of mating disruption is applied only by a minority of farmers, who act individually without any obligation either to publish research results or to make the data available to others.
Sesamia nonagrioides Lefébvre (Lepidoptera: Noctuidae) has a fairly wide range of host plants. Th... more Sesamia nonagrioides Lefébvre (Lepidoptera: Noctuidae) has a fairly wide range of host plants. The present study tests the egg laying preference of S. nonagrioides on four potential host plants (maize, sweet and fiber sorghum and johnshongrass) with respect to several life history traits. No choice and two choice tests in all possible combinations were conducted. Concerning no choice tests, significantly higher number of eggs were laid on sweet sorghum (282.5 eggs/female) in relation to the other tested plants. Moreover, viability of eggs that were laid on sweet sorghum was significantly higher in relation to those that were laid on johnsongrass. Longevity of females reared on maize plants was significantly greater compared with the other test plants except johnsongrass. Furthermore, pre-oviposition period of females reared on maize was significantly longer (2.4-fold) compared with that on sweet sorghum and johnsongrass. Similarly post-oviposition period of females reared on maize was significantly longer compared with that on fiber sorghum. On two choice tests significantly fewer eggs were laid on sweet sorghum than on maize. On the other hand, significantly more eggs were laid on sweet sorghum than on fiber sorghum and johnsongrass. We discuss the potential of secondary hosts to be used as trap plants.
"The risk of insects evolving resistance to Bt transgenic crops is a major concern in agriculture... more "The risk of insects evolving resistance to Bt transgenic crops is a major concern in agriculture. In Lepidoptera, one of the factors associated with resistance to Bt toxin is the cadherin Cry1A toxin receptor in the membranes of larval midgut cells. A cDNA encoding a putative Cry1A toxin receptor with high similarity to cadherin sequences identified in other Lepidoptera, was isolated from Sesamia nonagrioides (Lepidoptera: Noctuidae). Polymorphisms were identified in cadherin sequences from S. nonagrioides populations from three geographic regions in Greece. In addition, Barcoding-High Resolution Melting (HRM) analysis using mitochondrial cytochrome oxidase (COI) sequences were implemented to distinguish the different geographical populations of S. nonagrioides. The characterization of S. nonagrioides cadherin sequences in combination with an HRM-COI assay may serve as an efficient tool for distinguishing different Sesamia populations and potentially Bt resistant vs susceptible individuals aiming at rapid monitoring of Bt resistance in the field."
The effect of various constant temperatures on survival, development and adult longevity of Sesam... more The effect of various constant temperatures on survival, development and adult longevity of Sesamia nonagrioides Lefebvre (Lepidoptera: Noctuidae) was studied under laboratory conditions. The following temperatures were tested: 14, 17, 21, 25 and 31oC. The percentage of individuals that completed development at each temperature as well as the days needed for the emergence of the pupa and adult eclosion were measured. Adult longevity was estimated under the same conditions. Development time decreased significantly with increasing temperature within the range 14–25oC. Survival was higher at medium temperatures (17–25oC) in comparison with that at more extreme temperature regimens (14 and 31oC). Egg and first larval instars were the stages where S. nonagrioides suffered the highest mortality levels at all temperatures. The highest survival was recorded with experimental individuals aging between the third and fifth larval instar. Thermal requirements of development (developmental thresholds, thermal constant, optimum temperature) of S. nonagrioides were estimated with application of linear and one nonlinear models (Logan I). Upper and lower developmental thresholds ranged between 31.2 and 36.2 and 7.0 and 10.3oC, respectively. The optimum temperature for development (where maximum rate of development occurs) was estimated at between 28.1 and 30.3oC. The thermal constant for total development was estimated at 1,000.0 degree-days. Adult longevity was also affected by temperature, as it was significantly reduced at higher temperatures (21–31oC) compared to the lower ones (14 and 17oC). This information would be useful in determining the critical temperatures which may affect the distribution of S. nonagrioides concerning potential climate change.
The larva of codling moth Cydia pomonella (Tortricidae, Lepidoptera) is known as the worm in the ... more The larva of codling moth Cydia pomonella (Tortricidae, Lepidoptera) is known as the worm in the apple, mining the fruit for food. We here show that codling moth larvae are closely associated with yeasts of the genus Metschnikowia. Yeast is an essential part of the larval diet and further promotes larval survival by reducing the incidence of fungal infestations in the apple. Larval feeding, on the other hand, enables yeast proliferation on unripe fruit. Chemical, physiological and behavioral analyses demonstrate that cod- ling moth senses and responds to yeast aroma. Female moths are attracted to fermenting yeast and lay more eggs on yeast- inoculated than on yeast-free apples. An olfactory response to yeast volatiles strongly suggests a contributing role of yeast in host finding, in addition to plant volatiles. Codling moth is a widely studied insect of worldwide economic importance, and it is noteworthy that its association with yeasts has gone unnoticed. Tripartite relationships between moths, plants, and microorganisms may, accordingly, be more widespread than previously thought. It, therefore, is important to study the impact of microorganisms on host plant ecology and their contribution to the signals that mediate host plant finding and recognition. A better comprehension of host volatile signatures also will facilitate further development of semiochemicals for sustainable insect control.
The effect of various constant temperatures on survival, development and adult longevity of Ventu... more The effect of various constant temperatures on survival, development and adult longevity of Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae) parasitizing larvae of Plodia interpunctella Hübner (Lepidoptera: Pyralidae) was studied under laboratory conditions. The following temperatures were tested: 15, 17.5, 20, 22.5, 25, 27.5, 30 and 32.5oC. The percentage of parasitoids that completed development at each temperature as well as the days needed for the emergence of the parasitoid’s pupa and adult eclosion were measured. Adult longevity was estimated under the same conditions. Survival of V. canescens was significantly higher at 25 and 27.5oC compared to 17.5, 20, 30 and 32.5oC. No individual of V. canescens managed to complete development at 15oC. Overall, developmental time decreased significantly with increasing temperature within the range of 17.5 – 27.5oC. The lowest developmental time was observed at 27.5oC while the highest at 17.5oC. Upper and lower threshold temperatures for total development were estimated at 36.2 and 13.2oC, respectively. Optimum temperature for development and thermal constant were 30.6oC and 312.5 degree-days, respectively. Adult longevity was also affected by temperature, as it was significantly reduced at higher temperatures compared to the lower ones. This information would be useful in determining the potential of using V. canescens as a biological agent in IPM programs, by optimizing mass rearing and release techniques of the parasitoid.
The cold hardiness profile of immature and adult stages of the Mediterranean flour moth, Ephestia... more The cold hardiness profile of immature and adult stages of the Mediterranean flour moth, Ephestia kuehniella was investigated in the laboratory. Supercooling point (SCP) of early instars, late instars, pupae and adults of E. kuehniella was determined using a circulating bath with a cooling rate of 1ºC/min. Mean SCP of pupae was significantly lower (-23.3ºC) in relation to early and late instars (-16.1 and –19.5ºC, respectively), but did not differ significantly regarding adult ones (-21.6oC). Moreover, mortality at sub-zero temperature was estimated by cooling eggs, early instars, late instars, pupae and adults to -5, -7.5, -10 and -12.5ºC for 30, 60, 90 and 120 min. Main effects of temperature, exposure time and developmental stage on mortality proved to be significant. Two-way interactions as well as the three-way interaction between all tested factors also proved to be significant in most cases. Generally, pupae and adults were the most cold-tolerant, followed in decreasing order by late instars, early instars and eggs. However, when exposure temperature declined to -12.5oC, no significant differences were observed between the developmental stages in all exposure times, suggesting that low temperatures as low as -12.5oC are quite harmful to all developmental stages. Complete mortality has been observed only when early instars, late instars and adults were exposed to -12.5oC for 120 min. In all tested temperature regimes mean lethal time (LTime50) of pupae was higher compared to the other developmental stages. Similarly, in all exposure times mean lethal temperature (LTemp50) of pupae was lower in relation to the other developmental stages. Non-freezing injury above the SCP was well documented for all stages of E. kuehniella indicating a pre-freeze mortality. The potential of using low temperatures to control E. kuehniella is discussed.
Sesamia nonagrioides Lefébvre (Lepidoptera: Noctuidae) is considered one of the most destructive ... more Sesamia nonagrioides Lefébvre (Lepidoptera: Noctuidae) is considered one of the most destructive pests of corn in the Mediterranean region. The purpose of the present study was to investigate some aspects of the cold tolerance of non-diapausing and diapausing laboratory reared larvae of S. nonagrioides, as well as of field-collected larvae, taking into consideration various parameters, such as supercooling ability, mean lethal temperature and accumulation of cryoprotectant substances, in relation to diapause. Our results provide evidence that S. nonagrioides has limited cold tolerance as it displays a low ability of supercooling. This is strongly supported by the fact that mortality of the individuals occurred after extended exposure to subzero temperatures, equivalent or slightly lower to their mean supercooling point. However, lethal temperatures of diapausing larvae were significantly lower in relation to that of non-diapausing larvae, indicating the existence of a direct link between diapause and cold tolerance. Regarding the role of cryoprotectant substances, accumulation of glycerol seems to be closely related to diapause, in contrast to accumulation of trehalose, which is more related to exposure to low temperatures slightly higher than 0oC. Finally, nondiapausing larvae of different instars displayed a similar ability of supercooling and tolerance to low temperatures as well as accumulation of cryoprotectant substances. The ecological significance of our findings on cold tolerance of this species is being discussed with particular reference to the microclimate observed in northern Greece.
The major pest of maize in Mediterranean Europe, the stem borer Sesamia nonagrioides (Lefèbvre) (... more The major pest of maize in Mediterranean Europe, the stem borer Sesamia nonagrioides (Lefèbvre) (Lepidoptera: Noctuidae), has a fragmented distribution, north and south of the Sahara. The present study aimed: (1) to clarify the uncertain taxonomic status of the Palearctic and sub-Saharan populations which were first considered as different species and later on as subspecies (Sesamia nonagrioides nonagrioides and Sesamia nonagrioides botanephaga) and (2) to investigate the origin of the Palearctic population which extends from Spain to Iran, outside what is considered typical for this mainly tropical genus. We reconstructed the evolutionary history of both populations using one nuclear and two mitochondrial genes. The sub-Saharan taxon was fragmented in two isolated populations (West and East) whose mitochondrial genes were distant by 2.3%. The Palearctic population was included in the East African clade and its genes were close or identical to those of a population from Central Ethiopia, where the species was discovered for the first time. Similarly, in Africa, the alleles of the nuclear gene were distributed mainly in two West and East clades, whereas some Palearctic alleles belonged to the West clade. The Palearctic population originated therefore from East and West Africa and is the progeny of the cross between these two African populations. The main species concepts were in agreement, leading to the conclusion that the three populations are still conspecific. In the surveyed regions, the species therefore does not include two subspecies but three isolated populations. The Palearctic population suffered from severe bottlenecks that resulted in the fixation of one East African mitochondrial genome and the large reduction in its genetic diversity compared to the African populations. The data suggest that natural colonization of the Palearctic region was more plausible than human introduction. The allelic distribution of the Palearctic population was similar to that of species that survived the last glaciation. It is concluded that the African populations expanded during the last interglacial, crossed the Sahara and mixed in North Africa where fixation of the East mitochondrial genome occurred. The species then colonized Europe westward through only one eastern entrance. The coalescent-based estimate of the time to the ancestor of the Palearctic population was 108 000 years, which is consistent with this scenario.
Uploads
Articles by Stefanos S Andreadis
L. and spearmint Mentha spicata L. (Lamiaceae) were tested against two major stored products pests
Ephestia kuehniella (Zeller) and Plodia interpunctella (Hu¨ bner) (Lepidoptera: Pyralidae). Various oil
doses (0.5, 2.5, 5, 50, 250, 500, 1,000, and 1,500 ml/liter air), for an exposure period of 24 h, were tested.
The essential oils were subjected to gas chromatography–mass spectrometry analysis and revealed that
the major compounds were for spearmint oil carvone (67.1%) and limonene (þ1,8 cineole; 14.3%) and
for basil oil linalool (45.9%), 1,8 cineole (16.7%) and eugenol (10.3%). Apart from a few exceptions, no
significant differences in insecticidal action were observed between basil and spearmint oil. Both oils
were highly effective against adult moths, given that notable mortality (>80%) was recorded after exposure
to low doses such as 2.5 ml/liter. Noteworthy, egg mortality was also recorded, reaching 73–79% for
basil and 56–60% for spearmint. Toxicity data indicated that larvae and pupae were the most tolerant
stages in all cases. Larval mortality never exceeded 21 and 18%, for basil and spearmint, respectively, irrespective
of moth species. Basil and spearmint oils displayed mortalities as high as 38 and 28% in pupae.
Lethal doses (LD50 and LD99) values were estimated via probit analysis. Developmental stage proved to
be a significant factor, whereas the effect of oil species on insect mortality was insignificant. With the exception
of adult individuals, basil and spearmint oils did not show satisfactory overall insecticidal activity
against E. kuehniella and P. interpunctella.
(Diptera: Culicidae), which is considered the primary bridge
vector ofWest Nile Virus (WNV) to humans, is a wide spread
insect pest with medical importance and consists of two
distinct bioforms, Cx. pipiens f. pipiens and Cx. pipiens f.
molestus. Here, we consider the adult lifespan of male and
female Cx. pipiens f. pipiens under controlled conditions at
five constant temperature regimes (15, 20, 25, 27.5, and
30 °C). Our results show that adult longevity was affected
by temperature, as it significantly decreased with increase in
temperature. At the highest tested temperature, mean adult
longevity did not exceed 12 days for both sexes and thus
makes impossible the risk ofWNV transmission. On the other
hand at the lowest temperature, longevity was extremely high
with some individuals surviving up to 129 and 132 days,
males and females, respectively, and thus enable them to
function as potential vectors of WNV for a prolonged period
of time. As far as sex is concerned, adult females displayed a
1.2–1.4-fold longer longevity compared to the male ones.
However, this difference was significant only at the lowest
and highest tested temperature regime. This information is
useful in determining the critical temperatures which may
affect the distribution of Cx. pipiens and consequently the risk
of WNV transmission. Moreover, the effect of environmental
temperature should be considered when evaluating the abundance
of these species
pests of stored products. Low temperatures have been extensively used to control stored-product insects as an alternative
to the application of traditional pesticides. However, most studies have focused on the cold hardiness profile of the major
stored-product pests. The objective of this study was to investigate how factors such as age, food, host availability and
acclimation affect the cold tolerance of V. canescens by determining its supercooling capacity.
RESULTS:Youngadults displayed significantly lower supercoolingpoints (SCPs) thanolder adults, irrespective of the availability
of a host. Host availability had a moderate effect on supercooling, whereas food consumption resulted in a significant
enhancement of SCP. Acclimation to low temperatures increased the supercooling capacity considerably. Furthermore, an
increase in the duration of exposure to acclimation temperature resulted in lower SCPs.
CONCLUSION: Adults of V. canescens displayed an enhanced ability to supercool, however, they appear to be less cold tolerant
than their respective hosts. This information would be useful in determining the potential of using V. canescens as a biological
agent in Integrated PestManagement (IPM) programs, taking into consideration the adverse effects of low temperatures on its
survival.
L. and spearmint Mentha spicata L. (Lamiaceae) were tested against two major stored products pests
Ephestia kuehniella (Zeller) and Plodia interpunctella (Hu¨ bner) (Lepidoptera: Pyralidae). Various oil
doses (0.5, 2.5, 5, 50, 250, 500, 1,000, and 1,500 ml/liter air), for an exposure period of 24 h, were tested.
The essential oils were subjected to gas chromatography–mass spectrometry analysis and revealed that
the major compounds were for spearmint oil carvone (67.1%) and limonene (þ1,8 cineole; 14.3%) and
for basil oil linalool (45.9%), 1,8 cineole (16.7%) and eugenol (10.3%). Apart from a few exceptions, no
significant differences in insecticidal action were observed between basil and spearmint oil. Both oils
were highly effective against adult moths, given that notable mortality (>80%) was recorded after exposure
to low doses such as 2.5 ml/liter. Noteworthy, egg mortality was also recorded, reaching 73–79% for
basil and 56–60% for spearmint. Toxicity data indicated that larvae and pupae were the most tolerant
stages in all cases. Larval mortality never exceeded 21 and 18%, for basil and spearmint, respectively, irrespective
of moth species. Basil and spearmint oils displayed mortalities as high as 38 and 28% in pupae.
Lethal doses (LD50 and LD99) values were estimated via probit analysis. Developmental stage proved to
be a significant factor, whereas the effect of oil species on insect mortality was insignificant. With the exception
of adult individuals, basil and spearmint oils did not show satisfactory overall insecticidal activity
against E. kuehniella and P. interpunctella.
(Diptera: Culicidae), which is considered the primary bridge
vector ofWest Nile Virus (WNV) to humans, is a wide spread
insect pest with medical importance and consists of two
distinct bioforms, Cx. pipiens f. pipiens and Cx. pipiens f.
molestus. Here, we consider the adult lifespan of male and
female Cx. pipiens f. pipiens under controlled conditions at
five constant temperature regimes (15, 20, 25, 27.5, and
30 °C). Our results show that adult longevity was affected
by temperature, as it significantly decreased with increase in
temperature. At the highest tested temperature, mean adult
longevity did not exceed 12 days for both sexes and thus
makes impossible the risk ofWNV transmission. On the other
hand at the lowest temperature, longevity was extremely high
with some individuals surviving up to 129 and 132 days,
males and females, respectively, and thus enable them to
function as potential vectors of WNV for a prolonged period
of time. As far as sex is concerned, adult females displayed a
1.2–1.4-fold longer longevity compared to the male ones.
However, this difference was significant only at the lowest
and highest tested temperature regime. This information is
useful in determining the critical temperatures which may
affect the distribution of Cx. pipiens and consequently the risk
of WNV transmission. Moreover, the effect of environmental
temperature should be considered when evaluating the abundance
of these species
pests of stored products. Low temperatures have been extensively used to control stored-product insects as an alternative
to the application of traditional pesticides. However, most studies have focused on the cold hardiness profile of the major
stored-product pests. The objective of this study was to investigate how factors such as age, food, host availability and
acclimation affect the cold tolerance of V. canescens by determining its supercooling capacity.
RESULTS:Youngadults displayed significantly lower supercoolingpoints (SCPs) thanolder adults, irrespective of the availability
of a host. Host availability had a moderate effect on supercooling, whereas food consumption resulted in a significant
enhancement of SCP. Acclimation to low temperatures increased the supercooling capacity considerably. Furthermore, an
increase in the duration of exposure to acclimation temperature resulted in lower SCPs.
CONCLUSION: Adults of V. canescens displayed an enhanced ability to supercool, however, they appear to be less cold tolerant
than their respective hosts. This information would be useful in determining the potential of using V. canescens as a biological
agent in Integrated PestManagement (IPM) programs, taking into consideration the adverse effects of low temperatures on its
survival.
Οι ανακαλύψεις και οι καταργήσεις εντομοκτόνων συνεχίζονται καθημερινά και η αύξηση της γεωργικής παραγωγής στην περίοδο οικονομικής κρίσης που περνάει η χώρα μας είναι επιβεβλημένη. Αυτή συνδέεται με την κατάλληλη λήψη φυτοπροστευτικών μέτρων για την αντιμετώπιση των εντόμων που την καταστρέφουν. Η εφαρμογή της φυτοπροστασίας είναι μία οικονομική δραστηριότητα του ανθρώπου, η οποία τείνει στη λήψη του μέγιστου δυνατού οικονομικού αποτελέσματος ενώ παράλληλα δεν πρέπει να επηρεάζει αρνητικά το περιβάλλον (οικοσύστημα). Η εντατικοποίηση της γεωργικής παραγωγής όμως και η πλημμελής ενημέρωση οδηγούν πολλούς παραγωγούς στο να χρησιμοποιούν περισσότερους ψεκασμούς και μεγαλύτερες δόσεις φυτοπροστατευτικών προϊόντων συντελώντας αφ’ ενός στην αύξηση της ανθεκτικότητας και αφ’ εταίρου στην διατάραξη της βιολογικής ισορροπίας. Πολλοί φυσικοί εχθροί των εντόμων εξοντώνονται και δευτερεύοντες εχθροί των καλλιεργειών γίνονται πρωτεύοντες.
Θεωρούμε ότι το παρόν σύγγραμμα είναι χρήσιμο και απαραίτητο για όλους τους Γεωπόνους/Γεωτεχνικούς που ασχολούνται με την φυτοπροστασία ή τα φυτοπροστατευτικά προϊόντα. Η ανάγκη της έγκαιρης και κατάλληλης φυτοπροστασίας ήταν ο γνώμονας ώστε στο σύγγραμμα αυτό να αναφερθούν τόσο η εξωτερική μορφολογία, οι ζημιές και η βιολογία όσο και οι διάφορες μέθοδοι αντιμετώπισης των κυριότερων εντόμων που προσβάλλουν όλες τις γεωργικές καλλιέργειες.