Effect of particle size of soft wheat flour on the development of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The effect of soft wheat flours, characterized by different particle size, protein and starch content, on the development of Ephestia kuehniella was studied. The attractiveness of the substrata to first and third instar larvae was also considered.The different protein content of the flours did not significantly affect the development of E. kuehniella, nor did it affect the ability of the flours to attract larvae. In tests with soft wheat flours with the same nutritional value but different particle size, the highest mean number of adults and the shortest developmental period were recorded on samples with greatest particle size (250-419 μm).In order to test the attractiveness of soft wheat flour to larvae, a one-way olfactometer was used. There were no significant differences observed in the number of first and third instar larvae found on flours with different protein composition and particle size. Larvae of this species show limited mobility, in fact few individuals of either instar can reach the flour from a distance of 2 m. No larvae of either instar contacted the different substrata from a distance of 2.5 m.     

Inherited sterility in Mediterranean flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae): Effect of gamma radiation on insect fecundity, fertility and developmental period

The effects of gamma radiation on the fecundity, fertility, longevity, development and level of inherited sterility in the Mediterranean flour moth Ephestia kuehniella were determined. Newly emerged virgin Mediterranean flour moth adults were irradiated with 100, 200, 400 and 600 Gy in a ⁶⁰Co irradiator with a source strength of ca. 3811 Ci and a dose rate of ca. 1 Gy/min. Laboratory studies revealed that radiation did not effect the longevity of irradiated male and female adults. Inherited deleterious effects of gamma radiation were observed in the F₁ and F₂ generations. Fecundity and the daily egg laying pattern of irradiated and unirradiated females mated to irradiated males was not significantly different from untreated controls. Adverse effects of gamma radiation were observed in the percentage egg hatch and rate of development. Levels of sterility in the P₁, F₁ and F₂ generations were higher than that of untreated controls. The doses of radiation also had a significant effect on the time from oviposition to larval eclosion or adult emergence. Mortality increased with radiation dose. The incidence of larval and pupal mortality was higher in the F₂ than in the F₁ generation.     

The influence of temperature and humidity on the life-cycle of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The development of Ephestia kuehniella was followed carefully on white flour at constant temperatures ranging from 7.5° to 31°C at humidities from 0 to 75% r.h. The lower limit of temperature for complete development was about 12°C although a few adults of a stock collected recently emerged at 10°C. Adults emerged at 28 but not at 31°C. Generally, development took longer and survival was poorer at 40 than at 70% r.h. However, at 20 and 25°C survival was good even at 15% r.h., and at 25°C, 18 out of 50 larvae reached the adult stage at a humidity near 0% r.h. Development was fastest at 25°C, 75% r.h., taking a mean of 74 days from oviposition to adult emergence.Oviposition occurred at 7.5 but not at 5°C. Mating was unsuccessful at 12.5°C. Eggs hatched at all temperatures between 12 and 31°C at every r.h. used. A few eggs from two field stocks hatched at 10°C but none did so at 7.5°C.At 12 C no larvae pupated at humidities below 70% r.h., and none pupated at 31°C at any humidity. Larval development was most rapid at 25°C, 75% r.h., taking about 60 days. The shortest mean pupal period, 9 days, occurred at 28°C, 70% r.h. In an experiment with field stocks, many larvae pupated at 10°C but none at 7.5°C.This study confirms E. kuehniella as essentially a temperate species that prefers heated premises such as bakeries and mills for rapid development. Its ability to develop on food at a low e.r.h. fits it further for life in flour mills.     

Predation by Blattisocius tarsalis (Berlese) (Acari: Ascidae) on eggs of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The mean predation rate of female B. tarsalis on eggs of E. kuehniella was determined at 15°C, 21°C, and 27°C with prey densities of 3, 5, 10 and 15 eggs. Young eggs less than 24 h old were used as prey. Under all experimental conditions most eggs were only partially consumed, confirming the general theory that predatory mites leave most of the food content unutilized. A mean predation rate of 2.2-7.0 eggs destroyed in 24 h was found, reflecting that a large proportion of the available prey was destroyed. The result supports the view that the predatory mite B. tarsalis could be a relevant biological control agent against E. kuehniella in flour mills. It was further demonstrated that frozen moth eggs can be considered as an appropriate food source.     

The choice of probing sites by Bracon hebetor Say (Hymenoptera: Braconidae) foraging for Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

A direct behavioral assay was conducted to investigate the preferred habitat for host searching by the parasitoid Bracon hebetor (Hymenoptera: Braconidae). The effects of mating, feeding and post-emergence experience on female parasitoid choices of searching sites were also examined. B. hebetor appears to be directed to the habitat of its host through chemical cues originating from the host larvae, frass and adults. These cues elicit a series of directed responses by the female. Generally, the data showed that flour containing 30-day-old larvae was preferred by B. hebetor females. This was followed by the flour containing the frass, then the adult host, and finally the flour containing 10-day-old larvae. It appears that cues produced by young larvae were the weakest whereas cues produced by older ones were the strongest. Feeding seemed to be important in the location of the proper searching site. Although the cues were normally learned by the immature stages of the parasitoid, and were subsequently manifested in their responses as adults, adult experience increased the ability of the parasitoid to locate the suitable habitat for searching.     

Automatic dispensing of dichlorvos to control Ephestia kuehniella Zell. (Lepidoptera: Phycitidae) in flour mills

Dichlorvos applied weekly at the rate of 14.0 μg/l gave good control of Ephestia kuehniella in a flour mill. Other insects were also controlled. The insecticide was dispensed automatically by electrically operated sprayers when the mill was unoccupied. Exposure of test insects and chemical determinations of atmospheric concentrations showed that good distribution of vapour was obtained. Concentrations of dichlorvos were at a safe level for working well before the mill reopened after 8 hr. Contamination of flour was negligible. The method involves no disruption of routine working and there is no vapour hazard to workers.     

Insecticidal effect of Steinernema feltiae (Filipjev) (Nematoda: Steinernematidae) against Tribolium confusum du Val (Coleoptera: Tenebrionidae) and Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) in stored wheat

The confused flour beetle, Tribolium confusum, and the Mediterranean flour moth, Ephestia kuehniella, are important pests of stored grain products. The insecticidal effect of three strains (UK 76 [=Nemasys], USA/SC, and Hawaii) of the entomopathogenic nematode Steinernema feltiae was determined in the laboratory, in wheat, against these pests. The nematodes were applied at three dose rates: 100, 300 and 900 nematodes/insect individual. The Hawaii strain was most virulent against T. confusum adults and larvae, with a significant dose effect in the case of the larvae. Larval mortality of this species reached 79% and 100% after 7 and 14 d of exposure to the nematodes, respectively, at the highest dose applied. On the other hand, adult mortality of T. confusum did not exceed 66%. In the case of E. kuehniella larvae, USA/SC performed best causing 52% and 69% mortality after 7 and 14 d exposure, respectively, at the highest dose tested. Since very few data are available on the effect of entomopathogenic nematodes against these pests, it is concluded that the Hawaii and USA/SC strains of S. feltiae should be further investigated as promising biological control agents for T. confusum and E. kuehniella.     

Studies on three moth species in a Scottish port silo, with special reference to overwintering Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae)

During the winter of 1973–1974, enormous numbers of fully-fed, last instar larvae of Ephestia kuehniella (Zeller) were discovered in a large Scottish port silo where previously the endemic moth infestation had been almost entirely Endrosis sarcitrella (L.) and Hofmannophila pseudospretella (Stainton). E. kuehniella had previously been uncommon in this silo as in unheated silos elsewhere in Britain.

During 1974–1976 E. kuehniella was most abundant on the topmost floors of the silo, particularly inside the tops of grain bins where previously E. sarcitrella had been abundant. E. sarcitrella, however, was still the more abundant on the storage floors and at the bin bottoms. H. pseudospretella was widespread throughout the buildings, though less concentrated locally.

In September, most of the E. kuehniella larvae found were early instars less than half grown but by December the smallest larvae seen approached half grown. This gradual increase in mean larval length continued through the winter, although considerable mortality of large larvae occurred after December in some areas. However, some last instar larvae appeared to enter a diapause in the autumn and did not pupate until the following May. Adults of E. sarcitrella commenced to emerge in March, and of the other two species in June.     

Diapause in twenty populations of Ephestia cautella (Walker) (Lepidoptera: Pyralidae) from different parts of the world

Population samples of Ephestia cautella from difierent parts of the world were examined under various conditions of temperature and photoperiod for the incidence of diapause. In all but one of the twenty samples, larvae wandered for extended periods in search of sites to pupate, and diapause lasted over 50 days in some individuals from fifteen samples at 20°C, including five from the tropics. Some larvae of all fifteen samples diapaused in constant darkness but larvae from only eight, including just one from the tropics, diapaused in short photoperiods, and from only five of these, in constant light. Only one population, that in which diapause had previously been reported, diapaused at 25°C. Except in samples of this and three other populations, the proportion of larvae entering diapause did not exceed 50% under any of the conditions tested.The duration of diapause was in general quite short, mean times to pupation ranging from about 4–15 weeks. At 20°C, individuals from seven populations diapaused for longer than 12 weeks, and only a very few from three populations diapaused for over 20 weeks. Diapause is thus unlikely to enable E. cautella to overwinter in the UK in unheated premises.     

Influence of different diets on some biological parameters of the Mediterranean flour moth,Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

The Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae), is one of the most important pests of stored products, especially damaging cereals. Besides pest status, its eggs and larvae are commonly used for mass rearing of many natural enemies. Different diets are suggested for the production of E. kueniella, but the influence of diet supplements, such as yeast and glycerine on the performance of E. kuehniella diets are not clearly understood. In the present study, we investigated the effects of several diet ingredients on some major biological parameters of E. kuehniella. Ten diets based on different combinations of wheat flour, cornmeal, wheat bran, glycerine and yeast were tested in the experiments. Twenty eggs of E. kuehniella were added into 5 g of each diet within separate plastic cylindrical containers (5 cm height × 3 cm diameter) and incubated in climate rooms at 25 ± 1 °C and 60 ± 10 Relative Humidity (R.H) on a 14 h light: 10 h dark photoperiod. Pupal weight, developmental period, emergence ratio, fecundity and fertility were determined. The diet containing wheat flour, wheat bran, glycerine and yeast in a percentage of 53.33, 26.67, 15 and 5%, respectively, resulted in shorter development time and higher fertility, and could be used as an alternative to the standard diets currently used in insectaries.     

Orange-eye: A sex-linked recessive mutation in Ephestia cautella (Walker) (Lepidoptera: Pyralidae)

A new eye color mutant, orange eye (O), is described for Ephestia cautella. Preliminary data revealed that this mutation was inherited as a sex-linked recessive. The character is generally recognizable in only the late pupae and adult stages. The viability and reproductive potential of this strain are not significantly different from the wild type.     

Modelling heat-disinfestation of dried fruits on “biological model” larvae Ephestia kuehniella (Zeller)

The effects of heat treatment on the survival of isolated Ephestia kuehniella Zeller larvae were examined. Larvae were treated in a specific device at a temperature range of 46 to 70 °C. Statistical analysis of the data demonstrated that the thermal survival kinetics was best represented by a 2-parameter Weibull model above 50 °C. The mortality of larvae only occurs beyond a critical temperature of 41.6 °C ± 2.5 °C. A 2D axial-symmetric model of heat transfer (convection, microwave at 915 MHz) was developed for cocoa bean and date palm. It was combined with the survival rate of larvae (Weibull model) and some z-values (from literature) are used for calculating a “food quality index” degradation kinetics. The intensive heating/convection process may not be adaptable for food products at low water activity due to high surface product temperatures. The use of microwave heating for date fruits and conventional hot air treatments for cocoa beans is recommended.     

Repellency and some biological effects of different ultrasonic waves on Mediterranean flour moth,Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae)

Ephestia kuhniella is one of the most important stored pests in the world. Repellency and biological effects of various ultrasonic signals with different frequencies and wave shapes on adult, larvae and pupae of the pest were studied in laboratory conditions. Choice and non-choice tests was performed by an invented signal generator device. In choice tests, different ultrasonic frequencies, and for each frequency, four different waveforms were emitted by the device and numbers of repelled moths were separately calculated. Dispersion patterns, weight and survival of the pest treated by the ultrasound were compared with control in non-choice tests. The choice tests indicated that shape and frequency of ultrasound significantly affected evasive behavior of the moths by the waves. The highest repellency effects of ultrasound were observed at frequencies of 43–45 kHz and wave shapes of Sin (x) and Cos (x). Male moths significantly were more affected by the ultrasound. In non-choice test, weights of the pest larvae and pupae and the larvae survival were significantly reduced when they treated by ultrasound with frequency 40–45 kHz and Sin (x) wave shape that emitted by specific pattern. Also, our findings showed that the larvae and adults considerably tend to avoid from the ultrasound source. Results of the study can be applied for control of the pest in store locations or silage.     

Suppression of laboratory populations of Ephestia cautella (Walker) (Lepidoptera: Pyralidae) by release of males with cytoplasmic incompatibility

Unidirectional cytoplasmically incompatible males of Ephestia cautella (Walker) were substituted for irradiation-sterilized males in a modification of the sterile-male release technique. Laboratory populations were greatly suppressed or eliminated by single releases of incompatible males at ratios of 14:1 or greater. Isolated populations in nature (i.e., within a closed warehouse) could probably be eliminated by using this technique, but release ratios as high as 100:1 might be necessary.     

Effect of gamma irradiation of phosphine-fumigated dates on the development of Ephestia cautella (Walker) (Lepidoptera: Pyralidae)

Possible toxicological effects from interactions between gamma radiation (1 KGy at 46 rad/s) and phosphine residues in fumigated dates were studied when the dates were fed to Ephestia cautella. The results showed comparable development, fecundity and fertility of this insect when reared on a complete diet of fumigated, irradiated, fumigated irradiated or untreated dates.     

Composition and insecticidal activity of essential oil from Pistacia lentiscus L. against Ectomyelois ceratoniae Zeller and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

This study reports investigations on the chemical constituents and fumigant toxicity of Pistacia lentiscus L. (Anacardiaceae) essential oil against two major stored-date insects, carob moth Ectomyelois ceratoniae Zeller and Mediterranean flour moth Ephestia kuehniella Zeller. Results showed that P. lentiscus essential oil contained terpinene-4-ol (23.32%), α-terpineol (7.12%) and β-caryophyllene (22.62%) as major compounds. Fumigant toxicity tests showed that P. lentiscus oil was more toxic to E. kuehniella (LC₅₀ = 1.84 μl/l, LC₉₅ = 5.14 μl/l) than E. ceratoniae (LC₅₀ = 3.29 μl/l, LC₉₅ = 14.24 μl/l). The fecundity and hatching rate of both insects decreased with increases in concentration or exposure time to the oil. At 136 μl/l air, fecundities and hatching rates were respectively 35 eggs/female and 42.86% for E. ceratoniae and 78 eggs/female and 29.49% for E. kuehniella.     

The effect of carbohydrates on nutritional preference and development of Mediterranean flour mouth,Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

In this study, the effect of different carbohydrates on food consumption, growth and development duration of Ephestia kuehniella Zeller (Lepidoptera:Pyralidae) larvae was investigated. 13 diets containing different carbohydrates were prepared. Control diet did not contain carbohydrates. The 8 diet contains 3% concentration of glucose, galactose, maltose, starch, arabinose, mannose, sucrose or fructose. 2 of the diets contains 10% or 30% starch. 2 of the diets contain a mixture of carbohydrates (2 Glucose: 1Fructose; 2 Fructose: 1 Glucose). According to the results, only the increase in food consumption does not indicate that a carbohydrate is a feeding stimulus. The conversion of carbohydrates is also important. Although the dietary consumption of arabinose is high, pupa dry weight, pupa lipid and pupa protein are not high. Conversely, although the consumption of the glucose-containing diet is low, the pupa dry weight and pupa lipid content are high. The glucose-fructose mixture is stimulant for E. kuehniella larvae. G2-F1 diet is the diet with high food consumption and growth performance. In addition, it was determined that as the starch concentration in the diet increased, the amount of consumption increased but the pupa dry weight, which is an indicator of fecundity, decreased. It is important result that the amount of pupa protein does not differ in diets except carbohydrate free diet and G2-F1 diet.     

The influence of photoperiod on the life-cycle of Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae)

Diapause in fully grown larvae of Ectomyelois ceratoniae was induced by low temperature and short photoperiods. When larvae were reared at 30°C, 70% r.h. there was no diapause in a light regime of 12 hr light followed by 12 hr darkness (12L/12D), and only 20% entered a weak diapause in continuous darkness. However, at 20°C, 70% r.h. there was no diapause in 16L/8D but almost all larvae entered diapause in 12L/12D. At 20°C diapause delayed adult emergence by an average of 111 days, compared with about 50 days at 30°C. Survival to adult at 30°C was 75% or more at most photoperiods, but at 12L/12D and 13L/11D it was less than 50%. At 20°C survival was about 70% at the two photoperiods tested.

A slight effect of photoperiod on non-diapause growth rates was observed. Above 16 hr light longer photoperiods reduced the mean developmental period from egg hatch to adult emergence, by 4 days at 20L/4D and 6 days at 24L/0D.

The significance of diapause in this species in relation to its potential as a pest is discussed.     

The influence of photoperiod on the life-cycles of Ephestia calidella (Guenée) and Ephestia figulilella Gregson (Lepidoptera: Phycitidae)

When reared at 30°C 70% r.h. and fed on a diet of wheat-feed, glucose and yeast, some larvae of Ephestia calidella and E. figulilella entered diapause at photoperiods of 13 hr light and less per day. In continuous darkness for 60 days, no E. calidella larvae exhibited diapause, but two E. figulilella larvae showed some delay in development in food infested by psocids. Under a light regime of 13 hr light followed by 11 hr darkness ($\text{13L}\text{11D}$), 45 per cent of E. figulilella but only 3 per cent of E. calidella larvae entered diapause. The critical photoperiod for both species was between $\text{12L}\text{12D}$ and $\text{13L}\text{11D}$. For both species, survival was good in continuous darkness and poor in continuous light. Wherever diapause was detected, it delayed adult emergence by an average of 48 days for E. calidella and 74 days for E. figulilella.When reared at 20°C 70% r.h. in continuous darkness for 140 days, 96 per cent and 91 per cent of E. calidella and E. figulilella larvae, respectively, entered diapause. In neither species was diapause observed at 20°C $\text{16L}\text{8D}$. In E. figulilella diapause did not appear at photoperiods longer than $\text{13L}\text{11D}$ at this temperature.Transfer of larvae which were in diapause after 60 days at 30°C in a $\text{12L}\text{11D}$ photoperiod to one of $\text{16L}\text{8D}$ reduced the range of emergence period for E. calidella by 15 days and for E. figulilella by 75 days, compared to controls left at $\text{12L}\text{12D}$. Mean development periods were shortened by 13 days and 54 days respectively. Insertion of a 30 day cold period at 5°C did not significantly hasten the termination of diapause.Similar effects were obtained when E. calidella larvae entered diapause at $\text{12L}\text{12D}$ and 20°C. In this case, transferring diapause larvae to the longer photoperiod reduced the development period range by more than half that of controls at $\text{12L}\text{12D}$. Mean development period was reduced by 63 days. E. calidella larvae entering diapause at 20°C appeared to possess a more intense diapause than those entering at 30°C.The significance of diapause in these species in relation to their potential as pests is discussed.     

Diapause induction in Ephestia elutella (Hübner) and Plodia interpunctella (Hübner) (Lepidoptera,Pyralidae) with a dawn-dusk lighting system

The incidence of diapause in larvae of Ephestia elutella and Plodia interpunctella under two light systems operated by solar switches was observed at 25°C. Both switches gave progressively shortening daylength, as would be experienced from early July onwards at a latitude of 52°N. One of the light systems incorporated a device, which took 60 min to change to, or from, full light to near darkness, giving a dawn and a dusk with the photophase. The other was controlled directly by the time switch itself, without any extended periods of changing intensity.Maximal percentages of E. elutella larvae entering diapause under the two systems were obtained with photoperiods half way through development of less than 13 hr 25 min and 13 hr 10 min respectively, measurements of photoperiod in the dawn-dusk system including the 1 hr dawn and 1 hr dusk. The mean critical photoperiod, here defined as that photoperiod giving half the maximum percentage of insects that enter diapause in response to photoperiod at a fixed temperature, was found to be 14 hr 15 min under the dawn-dusk system, and 14 hr 5 min under the other shortening daylength system. Comparison of the above results with the incidence of diapause under a series of fixed daylengths confirmed that the principal sensitive phase in E. elutella occurred early in the last larval instar.Over 70 per cent emergence occurred in batches of P. interpunctella within 7 weeks of egg laying under all lighting conditions tested. Maximal percentages of larvae entered diapause after rearing in total darkness, continual light, or photoperiods of 13 hr or less. The sensitive phase occurred around 8 days after hatching at 25°C, and the mean critical photoperiod was found to be about 13 hr 15 min under both shortening daylength systems, and under fixed photoperiods. Photoperiods of over 13 hr, or increased temperature, appeared to inhibit diapause in P. interpunctella. Light intensities below 1 lux influenced diapause in both species.