Oviposition by Mamestra brassicae (L.) (Lep., Noctuidae) in relation to age, time of day and host plant

The age at which females begin to lay, the daily pattern of oviposition, the influence of host-plant material on egg-laying as well as the host preference of Mamestra brassicae L. (Lep., Noctuidae) were investigated under laboratory conditions. The females began to oviposit during the third, fourth and fifth scotophase after emergence. A great variability in daily female fecundity was observed. The highest level of oviposition occurred during the fifth day. Females oviposited during the whole scotophase, but maximal oviposition occurred during the second hour. The females without host-plant material laid fewer eggs than females with host-plant material (cabbage leaves Brassica oleracea var. capitata ). In two-choice tests, the females preferred to oviposit on cabbage rather than chrysanthemum, but there was no difference in the mean number of eggs laid on cabbage and tomato. There were significantly greater mean numbers of total eggs deposited on tomato than on chrysanthemum.     

Oxygen consumption in Oreochromis niloticus (L.) in relation to development, salinity, temperature and time of day

Oxygen consumption of Oreochromis niloticus at different stages of development was studied in relation to salinity, temperature and time of day, using a Warburg apparatus. The oxygen consumption of newly hatched (0–14 h) larvae was 3.40 μl O₂ larva⁻¹ h⁻¹, of older yolk sac larvae 10.09 μl O₂ larva⁻¹ h⁻¹, and of one-month-old fry 32.99 μl O₂ larva⁻¹ h⁻¹. The QO₂ values showed a decrease with development and growth, ranging from 21.2–26.0 μl O₂ mg⁻¹ h⁻¹ in newly hatched larvae to 2.97 μl mg⁻¹ h⁻¹ in one-month-old fry. Changes in oxygen consumption occurred with salinity, the highest being at 17%o. Active larvae (12-24 mm T.L.) showed a doubling of consumption with a 10° C rise in temperature, and their Q₁₀ factor increased from 2.25 to 3.43 with increasing size. Day-old yolk-sac larvae, late yolk-sac larvae (5 days old) and fry of 12 14 mm length all showed a depression in oxygen consumption at midnight followed by a dawn rise.     

Flight initiation byProstephanus truncatus in relation to time of day, temperature, relative humidity and starvation

Studies were carried out in the laboratory on the influences of time of day, temperature, relative humidity and starvation on flight initiation byProstephanus truncatus (Horn) (Coleoptera: Bostrichidae). Flight occurred throughout the 12 h photophase and at the beginning of the scotophase but peaked at 2–0 h before darkness. Temperature exerted a significant effect on flight. The frequency of flight take-off increased with temperature over the range 20–30°C but declined sharply at 35°C. Flight activity increased with starvation up to a maximum at 2 days after which it began to decline.     

Flight patterns of Anarsia lineatella (Lep., Gelechiidae) in relation to degree--days heat accumulation in Northern Greece

The flight patterns of the peach twig borer Anarsia lineatella (Zeller) (Lepidoptera: Gelechiidae) were studied in two important and representative regions of peach production in Northern Greece. In order to determine the seasonal occurrence of the species, adult male moth flight was monitored from April till October (2005-2006) using 8 pheromone traps. The observation areas were located at the regions of Veria (lat. 40.32 degrees North) and Velvendos (lat. 40.16 degrees North). The first flight was observed from early May to early June in Veria and from late May to mid June in Velvendos. The 2nd and 3rd flights were observed from late July to early August and from late August to late September in both regions. The degree-days required for the first generation (431 Veria, 371 Velvendos) were fewer than for the 2nd (661 Veria, 504 Velvendos) and the 3rd generation (675 Veria, 506 Velvendos). A lower threshold temperature of 100 C was used in calculating daily day-degrees from March 1st. All the above data are valuable for the development of prediction models and for decision making in order to achieve better timing of treatments. Considering the increasing interest of biorational insecticides where precise timing of treatments is extremely important, degree-day models could be a useful tool for improving their efficacy in IPM.     

Patterns of oviposition by Sandia xami (Lepidoptera, Lycaenidae) in relation to food plant apparency

ABSTRACT.

• 1 The butterfly Sandia xami (Reakirt) has a very clumped yearly pattern of oviposition on its food plant Echeveria gibbiflora D.C., and the mean number of eggs per plant is always very low.
• 2 Three features of host plants are highly associated with the probability of being oviposited upon: height of plant; degree of conspicuousness; and degree of isolation from conspecific plants.
• 3 The relative importance of these factors as predictors of the probability of oviposition change according to the time scale considered: height and conspicuousness are more important over short (weekly) time intervals whilst isolation takes precedence over longer (yearly) periods.
• 4 It is hypothesized that the clumped pattern of oviposition is responsible for the low numbers of the butterflies relative to their very abundant food plant.

     

Activity and weight loss in relation to solar radiation in the polymorphic land snail Cepaea nemoralis

Shell spectral reflectance, activity and weight loss in the land snail Cepaea nemoralis were examined to test whether solar radiation has different effects on the behavioural and physiological responses of different morphs. A uniform area from the empty shells of different morphs was cut and a spectrophotometer was used to measure the spectral reflectance at wavelengths from 220 nm to 800 nm. Snails were put into cages made of mesh hardware cloth, and their activities were observed from dawn onwards on two hot, dry days. Weight loss of snails under shade and under direct sunlight was also measured.
The results show that unbanded morphs reflect more light than five-banded ones, but the yellow morphs reflect only a little more than pink morphs. Five-banded morphs became inactive more quickly than unbanded ones from dawn onwards, but the differences in activity patterns were not significant between pink and yellow morphs. There are significant differences in percent weight loss between snails placed under direct sunlight and under shade. The weight loss of different morphs under shade was not statistically different. But when exposed to sunlight, five-banded morphs lost more weight than pink and yellow unbanded morphs.
Because of their lower reflectance of solar radiation, the five-banded morphs are, in a hot, arid climate, at a selective disadvantage compared to unbanded morphs. However, they can avoid such selective disadvantage by actively seeking a shaded area, as all other morphs do in the field. Such behavioural habitat selection could help the maintenance of genetic polymorphisms in natural populations.     

Pheromone trap catches of the olive moth, Prays oleae (Bern.) (Lep., Plutellidae) in relation to olive phenology and degree-day models

Abstract:  The population dynamics of the olive moth, Prays oleae (Bern) (Lep., Plutellidae) was monitored using pheromone traps containing (Z)-7-tetradecenal, from 2000 to 2002 in abandoned and commercial olive groves of Bursa in north-western Turkey. The carpophagous generation lasted significantly longer than the phyllophagous generation. The degree-days required for the anthophagous generation were significantly shorter than that for the phyllophagous and carpophagous generations. The relationship between temperature accumulations and pheromone trap captures of male P. oleae in Bursa olive groves showed a significant sigmoid relationship for the phyllophagous and anthophagous flights. Although there was generally a linear relationship between cumulative male catch and olive tree phenology, the use of the prediction model for insecticide treatments was insufficient. Cumulative male catch–degree days together with the olive tree phenology model can be used as a forecasting method for proper timing of insecticide applications against anthophagous and carpophagous larvae in olive groves.     

Biological and Integrated Control of Plutella xylostella (Lep., Yponomeutidae) and Crocidolomia pavonana (Lep., Pyralidae) in Brassica Crops in Papua New Guinea

The major constraint to the production of good quality cabbage in Papua New Guinea (PNG) is posed by a complex of insect pests which includes the Diamondback Moth Plutella xylostella (L.) as the most prominent species. In order to evaluate the prospects of a classical control approach economically important major pests and their natural enemies were surveyed in three cabbage growing areas with distinct climatic regimes at low-, mid- and high-elevation. In the PNG highlands (Goroka and Tambul area, Western Highlands Province) the release and successful establishment of the P. xylostella -specific parasitoid Diadegma semiclausum (Hellen) reduced crop losses remarkably since 1995. Favourable circumstances, such as continuous brassica cultivation and low status of associated lepidopteran pests, particularly at Tambul (2400 m above sea level) with an almost temperate climate, were supportive for this approach. In the arid PNG lowlands (Laloki area, Central Province) the introduced P.xylostella -parasitoid Cotesia plutellae (Kurdjumov) exerted 80% parasitism in an experimental site, although a lasting establishment was not achieved in that location. Among several indigenous P. xylostella parasitoids Brachymeria phya (Walker) was a ubiquitous species but did not reduce the pest status of its host. Natural enemies of associated lepidoptera such as Crocidolomia pavonana (Zeller), Spodoptera litura (F.), Helicoverpa armigera (Hübner) and Hellula undalis (F.) were economically insignificant. Thus, insecticidal control, preferably selective, was still a requirement. In comparison to Bacillus thuringiensis -products (Delfin ® and Thuricide ® ) and the synthetic insect growth regulator Chlorfluazuron (Atabron ® ), best results were achieved in field trials with the commercial neem formulation NeemAzal ® ( Azadirachta indica A. Juss.) and an aqueous neem seed kernel extract from seeds of PNG grown trees. Besides its high efficacy against lepidopterous pests, neem also controlled the false mustard aphid Lipaphis erysimi (Kalt.), being of economic importance in the arid PNG lowlands. The prospects of integrating C. plutellae into a reduced insecticide spraying program as well as alternative cultural control measures are discussed.     

Developmental changes caused by metyrapone and azadirachtin in Spodoptera littoralis (Boisd.) (Lep., Noctuidae) and Galleria mellonella (L.) (Lep., Pyralidae)

Larvae of Spodoptera littoralis and Galleria mellonella reared on standard laboratory food were used in experiments with metyrapone and azadirachtin. Metyrapone in S. littoralis caused high elevation of metabolic rate which resulted in a significant increase of body-mass. This phenomenon was associated with precocious transformation to pupal stage. The same results were obtained after application of azadirachtin or neem oil. Restriction of reproduction was also observed in S. littoralis . Both these compounds influenced body pigmentation: the treated larvae was light green or light gray. Synthesis of melanin was inhibited. In Galleria mellonella , the effect was not as prominent.     

Effect of temperature on life table parameters of Podisus nigrispinus (Het., Pentatomidae) fed with Alabama argillacea (Lep., Noctuidae) larvae

Abstract: The influence of temperature on life table parameters of Podisus nigrispinus (Dallas) (Het., Pentatomidae) fed with Alabama argillacea (Hübner) (Lep., Noctuidae) larvae was studied. This predator was kept at constant temperatures of 20, 23, 25, 28, 30 and 33±0.2°C, at relative humidity of 60±10% and photoperiod of L : D 14 : 10. Gross (GRR) and net ( R ₀) reproductive rates of P. nigrispinus ranged from 1.6 to 366.6 and from 0.02 to 189.5 females/female at temperatures of 33 and 28°C, respectively; generation time ( T  ) ranged from 33.3 (33°C) to 85.5 (20°C) days; doubling time ( D ) from 0.82 (33°C) to 17.8 (20°C) days; intrinsic rate of increase ( r _m ) from −0.13 (33°C) to 0.12 (28°C) per day; and the finite rate of increase ( λ ) from 0.88 (33°C) to 1.12 (28°C) females/female added to the population per day. The ideal age to release P. nigrispinus should be when this predator presents higher reproductive values (VR _x ); that is, its adults are about 7 days old, independent of prevailing temperature. Population growth of P. nigrispinus was affected by temperature with maximum numerical response between 28 and 30°C. The negative population growth shown at 33°C may not occur in natural conditions due to milder microclimate in the cotton agroecosystem and due to oscillations of temperature in the course of the day.     

Effects of a kaolin-based particle film on oviposition and feeding of gypsy moth (Lep., Lymantriidae) and forest tent caterpillar (Lep., Lasiocampidae) in the laboratory

Abstract:  In the laboratory we investigated a kaolin-based crop protectant, Surround^® WP, that was mixed in a spray carrier (94% water, 2% methanol, 4% Triton X100) and applied as particle film against gypsy moth Lymantria dispar (L.) and forest tent caterpillar Malacosoma disstria Hubner. Paired-choice feeding tests showed that gypsy moth larvae were significantly (P < 0.05) less disposed to feed on red oak Quercus rubrus L. treated with high concentrations (60 and 120 g/l carrier) of kaolin than on untreated foliage. There was no significant difference (P > 0.05) between gypsy moth's consumption of kaolin-treated and untreated red oak when given a single food choice, but the adults were less inclined to oviposit on the kaolin-treated surfaces than on controls. However, no kaolin treatment completely deterred gypsy moth feeding or oviposition. Kaolin particle film did not influence forest tent caterpillar feeding and there were insufficient data to evaluate the effect of kaolin on the species' oviposition. The spray carrier did not increase the efficacy of the kaolin, but as an independent, albeit impractical treatment it constrained feeding by both insect species but did not affect gypsy moth oviposition. These initial laboratory findings suggest that applying kaolin-based particle film to forests would present significant challenges; but if these could be surmounted, the technique might assist in the management of gypsy moth but not likely in that of forest tent caterpillar.     

Functional response of the predators Podisus maculiventris (Say) and Podisus nigrispinus (Dallas) (Het., Pentatomidae) to the beet armyworm, Spodoptera exigua (Hübner) (Lep., Noctuidae): ef fect of temperature

Predation abilities of Podisus maculiventris and Podisus nigrispinus on caterpillars of the beet armyworm, Spodoptera exigua (Hübner), were compared at three different temperatures (18, 23 and 27°C) by performing functional response tests. In both species, predation capacity was a function of temperature and prey density: more prey were captured as temperature and number of prey offered increased. Results indicated that type II and III functional responses provided the best fit to the data obtained for P. nigrispinus at 18 and 23°C, and at 27°C, respectively. However, the data for P. maculiventris showed a better fit to type II at 18°C and to type III at higher temperatures. In both pentatomids the handling time decreased with increasing temperature. At higher temperatures, P. nigrispinus demonstrated greater predation rates than P. maculiventris . The implications of these findings for the control of caterpillar pests in glasshouses are discussed.     

The group postural behaviour of growing pigs in relation to air velocity,air and floor temperature

In three experiments with 6 piglets each (3 males, 3 females), given access to a pen with 4 plates having different surface temperatures and an air-velocity gradient, the group postural behaviour was recorded and analyzed.The results indicate that temperature control of the floor surface can realize the preferred comfort zone of growing pigs, as a function of age and air temperature.In the case of a constant floor temperature which was higher than the air temperature, as a function of age the pigs preferred a lying area with an enhanced air velocity (0.3 m s⁻¹) when the air temperature was 14–25°C.Hence, the animals' preference for a well-defined combination of air and floor temperature, as well as of air velocity, can be used as a trigger within the engineering and control system of the house environment to avoid behaviour-related problems.     

Lichen respiration in relation to active time, temperature, nitrogen and ergosterol concentrations

1. Respiration in eight lichen species was related to thallus hydration status, external temperature and to total nitrogen, chitin and ergosterol concentrations. Chitin is a nitrogenous and major compound of the fungal cell wall, and ergosterol is a sterol of the plasma membrane in fungi and sometimes in algae.
2. Hydration of previously dry thalli resulted in an initially high rate of respiration. Both the amplitude of this resaturation respiration and the time required to reach steady state varied among species. Generally, peak rates were one to three times higher than steady-state rates, which were reached 3–7 h after hydration.
3. Increases in external temperature also resulted in transient bursts in respiration. Again, both the amplitude of the burst and the time required to reach steady state varied among species. Also depending on species, a temperature increase from 5 to 15 °C resulted in two- to fivefold increases in steady-state respiration.
4. Steady-state respiration, at optimal thallus hydration and a given temperature, varied three- to sixfold among the species, when related to thallus dry mass. This difference correlated best ( r ² = 0·89) with their ergosterol concentration, where a doubling in ergosterol resulted in more than a doubling in respiration. Respiration correlated less well to total nitrogen or chitin.
5. The chitin to ergosterol ratio varied more than one order of magnitude between the species, where species with high nitrogen concentrations had the highest ratio. This implies that species with access to ample amounts of nitrogen can make more fungal cell walls in relation to plasma membrane surface area.     

Cartap resistance and synergism in populations of Tuta absoluta (Lep., Gelechiidae)

Abstract: Control failures of cartap when used against the tomato leafminer Tuta absoluta (Meyrick) in Brazil and a recent report of cartap resistance in Brazilian populations of this pest species led to the investigation of the possible involvement of detoxification enzymes on this phenomenon using insecticide synergists. The insect populations were collected from seven different sites in the states of Minas Gerais, Rio de Janeiro and São Paulo. These populations were subjected to insecticide-impregnated filter paper assays. The concentration–mortality assays were carried out for cartap alone and in a mixture (1 cartap : 10 synergist) with the synergists diethyl maleate, piperonyl butoxide and triphenylphosphate which, respectively, inhibit the enzymes glutathion-S-transferases, cytochrome P450-dependent monooxygenases and esterases. Resistance to cartap was observed in all populations when compared with the standard susceptible population, with resistance ratios ranging from 2.3- to 21.9-fold. Piperonyl butoxide was the most efficient synergist with cartap synergism ratios ranging from 1.3- to 21.0-fold and nearly completely suppressing the resistance to cartap in all of the populations studied, suggesting a major involvement of cytochrome P450-dependent monooxygenases as a cartap resistance mechanism in these populations of T. absoluta . Diethyl maleate and triphenylphosphate also synergized cartap in nearly every population, and they still provided partial suppression of cartap resistance in the leafminer populations studied. Therefore, glutathion-S-transferases and esterases seem to play a secondary role in cartap resistance in Brazilian populations of T. absoluta .     

Stability of field-selected resistance to insecticides in Plutella xylostella (Lep., Plutellidae) from Pakistan

Abstract:  To investigate fluctuation in susceptibility to insecticides, natural populations of Plutella xylostella were collected from the same field in the region of Multan, Pakistan, in late summer, mid-winter and early spring. After bulking up for a generation in the laboratory, the populations were examined against pyrethroids and organophosphates as well as newer insecticides (spinosad, indoxacarb and emamectin). Each population showed a broad range of variation in susceptibility to all chemicals. Comparison between populations collected in different times of years in 2003 and 2004 showed variation in susceptibility to organophosphates and pyrethroids. In winter, susceptibility to organophosphates increased, whereas it decreased in relation to pyrethroids. However, susceptibility to the newer insecticides was unchanged within the season. The results suggest that the fluctuation observed in susceptibility could be either associated with fitness costs of organophosphate and pyrethroids or cessation of insecticides. These results might have important implications in resistance management. We propose a strategy for application of insecticides in relation to P. xylostella management in Pakistan.     

Trigeminal chemosensitivity: Differences in relation to the time of the day

Day-night differences of trigeminal chemosensitivity were investigated in 18 healthy volunteers employing both pain-related cortical potentials and pain ratings in response to stimulation of the nasal mucosa with CO2. Day-night differences were found with N 1 P2 amplitudes, P2 latencies and pain ratings. It is concluded that the time of the day must not be ignored when human chemosensitivity is investigated at suprathreshold levels.      

Variation in the suitability of Pinus sylvestris to feeding by two defoliators, Diprion pini (Hym., Diprionidae) and Graellsia isabellae galliaegloria (Lep., Attacidae)

Abstract: Feeding bioassays were conducted on several Pinus sylvestris clones to establish if there were any differences in suitability for two pine defoliators: the sawfly Diprion pini L. (Hym., Diprionidae), which causes considerable damage in Europe, and the rare and protected moth Graellsia isabellae galliaegloria Oberthür (Lep., Attacidae). There were significant differences in survival, weight, sex-ratio and female fecundity of D. pini on Scots pine clones. However, sawfly survival appeared to be the most stable variable in time and three clone categories were revealed by conducting feeding bioassays on 16 clones. The survival of G. isabellae galliaegloria until the formation of the chrysalis was significantly different among clones. It varied from 35 to 75% but no clear clone category was distinguished . The two clone classifications according to insect survival showed differences. In particular, one unsuitable clone for D. pini development appeared to be favourable to moth development. The 3-carene richness of foliage was significantly linked with sawfly survival and the monoterpene composition of foliage was not linked with G. isabellae galliaegloria survival.     

A DNA marker to identify predation of Plutella xylostella (Lep., Plutellidae) by Nabis kinbergii (Hem., Nabidae) and Lycosa sp. (Aranaea, Lycosidae)

Abstract:  Predators are important biotic factors in the population dynamics of the diamondback moth, Plutella xylostella . A specific DNA marker was developed to detect P. xylostella in the gut contents of two polyphagous predators, Nabis kinbergii and Lycosa sp. A distinct 275-bp product was amplified by polymerase chain reaction (PCR) from the internal transcribed spacer (ITS-1) of the ribosomal gene of P. xylostella , but not from 11 other arthropod species collected from Brassica fields in South Australia. Fortuitously, the primer set could also amplify DNA products from two species and three varieties of Brassica plants, with the fragment size about 600 bp. When N. kinbergii was analysed after feeding a single fourth instar P. xylostella , 67% of individuals were positive with the 275-bp PCR product up to 16 h after feeding. Likewise, the PCR product was detected in 80% individuals of Lycosa sp. up to 72 h after feeding on a single fourth instar P. xylostella larva. Initial tests of samples collected from the field showed that the predation incidences for both N. kinbergii and Lycosa sp. determined by the 275-bp fragment corresponded to the density of P. xylostella in the field.