Indian Meal Moth Plodia Interpunctella Research Articles

Effects of low temperatures on quiescence in Trichogramma evanescens Westwood and T. chilonis Ishii reared on Plodia interpunctella (Hübner): implications for mass rearing

The egg parasitoids of the genus Trichogramma are important potential biological control agents for a wide range of lepidopteran pests. Cold storage of host eggs has been proposed as a valuable technique for ensuring the release of sufficient parasitoid numbers whenever it is needed. In this context, the impact of low temperatures to induce quiescence in T. evanescens Westwood and T. chilonis Ishii was studied using eggs of Indian meal moth Plodia interpunctella (Hübner). Prepupae of the parasitoids were stored for 15, 30, 45, 60 and 75 d at 4 °C, following a 7 d period of acclimation at 10 °C. Both parasitoid species seem to survive unfavorable temperature conditions by entering a state of quiescence. Parasitism, adult emergence, sex ratio and progeny quality were not affected by cold storage in either parasitoid species for up to 30 d of storage. Parasitized host eggs of P. interpunctella can be stored for up to 60 d at 4 °C for both parasitoids, but there was no emergence at 75 d. General productivity values gradually decreased as the duration of storage lengthened for both species. Our results clearly reveal that the eggs parasitized by these species can be stored for up to 30 d at 4 °C in a state of quiescence without much loss of their performance compared to the control eggs.

Comparative Effect of Dichlorvos and Ginger (Zingiber officinale L.) On the Indian Meal Moth (Plodia interpunctella hübner) Feeding on Zea mays Grains

Abstract Synthetic and natural insecticides have successfully controlled the Indian meal moth (Plodia interpunctella Hübner). However, little is known about how Indian meal moth reacts in a stressed environment caused by synthetic and botanical insecticides. Therefore, this study compared the effects of dichlorvos (DDVP) and ginger (Zingiber officinale L.) rhizome extract oil on larval and adult mortality, hatchability and adult emergence, and on neurotransmitters and digestive enzymes of Indian meal moth under laboratory conditions of 75 ± 5% relative humidity and 25 ± 5 °C. The insects were exposed to different concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5% of dichlorvos and ginger extract oil for 96 h. Ginger rhizome extract oil caused 100% mortality in newly emerged adult Indian meal moths within 96 h at all concentrations. DDVP and ginger extract oil were ineffective against the third instar larval stage of the Indian meal moth, at varying concentrations that caused adult mortality. DDVP and ginger rhizome extract oil significantly affected digestive enzymes and acetylcholinesterase activities at lethal concentrations used in treatment. Protease activity was significantly increased in larvae exposed to extract oil than DDVP. Acetylcholinesterase activities in the adult insects exposed to maize grains treated with DDVP were higher than those exposed to maize treated with ginger extract oil. DDVP and the ginger extract oil have significant effects on the digestive enzymes. Nevertheless, ginger extract oil increased larval protease activity more than DDVP.

Effect of some plant extract on Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyrallidae) on Pistacio fruits in Erbil-Kurdistan Region

Effect of some plant extract on Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyrallidae) on Pistacio fruits in Erbil-Kurdistan Region

Identification and functional characterization of female antennae-biased odorant receptor 23 involved in acetophenone detection of the Indian meal moth Plodia interpunctella.

The Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae), a globally distributed storage pest, relies on odors that are emitted from stored foods to select a suitable substrate for oviposition. However, the molecular mechanism underlying the chemical communication between P. interpunctella and its host remains elusive. In this study, 130 chemosensory genes were identified from the transcriptomes of 7 P. interpunctella tissues, and the quantitative expression levels of all 56 P. interpunctella odorant receptor genes (PintORs) were validated using real-time quantitative polymerase chain reaction. The functional characteristics of 5 PintORs with female antennae-biased expression were investigated using 2-electrode voltage clamp recordings in Xenopus laevis oocytes. PintOR23 was found to be specifically tuned to acetophenone. Acetophenone could elicit a significant electrophysiological response and only attracted mated females when compared with males and virgin females. In addition, molecular docking predicted that the hydrogen bonding sites, TRP-335 and ALA-167, might play key roles in the binding of PintOR23 to acetophenone. Our study provides valuable insights into the olfactory mechanism of oviposition substrate detection and localization in P. interpunctella and points toward the possibility of developing eco-friendly odorant agents to control pests of stored products.

Sampling Lasioderma serricorne (Coleoptera: Anobiidae) in 2 coffee bean warehouses in New Jersey.

Cigarette beetle, Lasioderma serricorne (F.), is one of the most common stored-product pests. We monitored their population dynamics and distribution in two coffee bean warehouses in New Jersey, USA, using pheromone traps and sticky traps during September 2018-October 2020, and light traps in 2020. The two warehouses only implemented treatment procedures for controlling Indian meal moth (Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)) during the study period. The first L. serricorne adult appeared on pheromone traps from late May to early June when temperature reached 21-22 °C, and the last L. serricorne adult appeared on pheromone traps from late October to mid-November when temperature dropped to 10-14 °C. The majority of L. serricorne was caught during July-October. Light traps caught 5.5- and 2.2-times more L. serricorne per trap than pheromone traps in Warehouse 1 and 2, respectively. Warehouse 1 had a significantly higher density of L. serricorne than Warehouse 2. The L. serricorne activity peaks were not always clear and varied between year and the two warehouses. Zero to 3 hot spots, where had the largest numbers of L. serricorne, were identified from July to October in each warehouse based on pheromone traps, and their locations were similar through the months both in 2019 and 2020. The L. serricorne counts from pheromone traps placed inside warehouse were at least 2.3-times more than those placed outside. Also, the L. serricorne active period outside of the warehouses was shorter than that from inside of the warehouses.

Larval and Pupal Silk Variation in the Indian Meal Moth (Plodia interpunctella): the Impact of Overcrowding and Temperature

The Indian meal moth (Plodia interpunctella) is becoming an important biological model to study silk. While there are many potential applications to materials science and medicine, many aspects of silk production in this species remain unknown. Here we characterize the silk of P. interpunctella by measuring the width of larval wandering and pupal silk strands and find that the latter is significantly thicker than the former. We also report intraspecific variation in pupal silk production in our lab-reared colony with a very small number of individuals forgoing pupal silk production entirely (< 4%). Overcrowding had no effect on silk formation, but exposure to elevated temperature reduced pupal silk production.

Genomic analyses provide insights into the genome evolution and environmental adaptation of the tobacco moth Ephestia elutella.

Ephestia elutella is a major pest responsible for significant damage to stored tobacco over many years. Here, we conduct a comparative genomic analysis on this pest, aiming to explore the genetic bases of environmental adaptation of this species. We find gene families associated with nutrient metabolism, detoxification, antioxidant defense and gustatory receptors are expanded in the E. elutella genome. Detailed phylogenetic analysis of P450 genes further reveals obvious duplications in the CYP3 clan in E. elutella compared to the closely related species, the Indianmeal moth Plodia interpunctella. We also identify 229 rapidly evolving genes and 207 positively selected genes in E. elutella, respectively, and highlight two positively selected heat shock protein 40 (Hsp40) genes. In addition, we find a number of species-specific genes related to diverse biological processes, such as mitochondria biology and development. These findings advance our understanding of the mechanisms underlying processes of environmental adaptation on E. elutella and will enable the development of novel pest management strategies.

Improved Quality Management of the Indian Meal Moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) for Enhanced Efficacy of the Sterile Insect Technique.

The sterile insect technique (SIT) is considered an environmentally friendly, autocidal control tactic to manage insect pests. This work dealt with the improvement of quality management of the Indian meal moth Plodia interpunctella (Hübner) for enhanced efficacy of the SIT. The results indicated that egg hatching of irradiated mature eggs of P. interpunctella was higher than that of younger eggs, indicating that mature eggs were significantly more tolerant than younger eggs. Moreover, our data revealed that a dose of 500 Gy completely prevented pupal formation in irradiated young and mature larvae. Crosses between irradiated and non-irradiated adults resulted in considerable variations in fecundity. The mating competitiveness index (CI) value was higher for a ratio of 5:1:1 (sterile male, fertile male, and fertile female, respectively) as compared with the ratio 1:1:1 for the irradiated individuals of all life stages. Low temperature (5 °C) maintenance of irradiated pupae significantly affected adult emergence. Using cylinders to assess flight ability, we found that the flight performance of adults that were developed from cold treated irradiated pupae was influenced by cylinder diameter, cylinder height and the number of hours the insects were in the cylinders. The percentage of DNA damage of the reproductive organs of adults developed from cold treated pupae that were irradiated with 100 and 150 Gy varied significantly. The results of this study should be used to implement pilot-scale field tests aiming at a sterile- to-fertile male ratio of 5 to 1.

Post-Harvest Insect Pests and Their Management Practices for Major Food and Export Crops in East Africa: An Ethiopian Case Study.

Ethiopian subsistence farmers traditionally store their grain harvests, leaving them open to storage pests and fungi that can cause contamination of major staple crops. Applying the most effective strategy requires a precise understanding of the insect species, infestation rates, storage losses, and storage conditions in the various types of farmers' grain stores. This study did a complete literature analysis on post-harvest pest and management measures with a focus on Ethiopia. The most frequent insect pests of stored cereals in this study were weevils (Sitophilus spp.), the lesser grain borer (Rhyzopertha dominica), rust-red flour beetle (Tribolium sp.), sawtoothed grain beetle (Oryzaephilus sp.), grain beetle (Cryptolestes spp.), Indian meal moth (Plodia interpunctella), and Angoumois grain moth (Sitotroga cerealella). Flour beetles (Tribolium spp.), sawtoothed beetles (Oryzaephilus sp.), flat grain beetles (Cryptolestes pusillus), and some moths have been identified as common stored product pests of stored oil seed, while bruchid beetles (Callosobruchus chinensis) and the moths were reported for pulses. Additionally, the storage pests in Ethiopia under varied conditions caused storage losses of 9-64.5%, 13-95%, 36.9-51.9%, and 2-94.7% in maize, sorghum, chickpeas, and sesame, respectively. To reduce the losses incurred, preventative measures can be taken before infestations or as soon as infestations are discovered. A variety of pest population monitoring systems for harvested products and retailers have been developed and recommended. In this context, reducing post-harvest grain losses is an urgent concern for improving food accessibility and availability for many smallholder farmers in Ethiopia and ensuring the nation's long-term food security.

Effects of High-Pressure Carbon Dioxide on the Sensory and Chemical Properties of Dried Dates and Its Toxicity against Galleria mellonella (L.) and Plodia interpunctella (Hübner)

The use of chemical pesticides can have many detrimental side effects, including environmental pollution, and be a threat to human health. Carbon dioxide (CO2) treatment, a relatively new method for storage pest management, can replace harmful chemicals. Dates, an important food worldwide, contains many minerals, fiber, and a variety of vitamins and are an important dried fruit export from Iran annually. Thus, control of the pests of dried dates by using eco-friendly agents that do not affect quality features are critical. In this study, larval mortality of the Indian meal moth (Plodia interpunctella (Hübner)) and the greater wax moth (Galleria mellonella (L.)), two key pests of stored products, especially dried dates, was studied after exposure to different CO2 pressures within 24 h. Mortality percentages of the third-instar larvae of both pests were increased with an increase in CO2 pressure. Sensory tests on the qualitative characteristics of the dates revealed that CO2 pressures did not affect their aroma, color, sweetness, sourness, crispness, firmness, and overall acceptance. The highest tested pressure (33.4 mol%) of CO2 also had no significant effects on the chemical properties of the date samples, including moisture content, pH, acidity, Brix value, reducing sugar, and total sugar. We conclude that atmospheric CO2 gas can provide a cost-effective and environmentally friendly method for controlling the insect pests of dried dates in addition to preserving their sensory and quality properties.

First record of the Indian meal moth Plodia interpunctella (Lepidoptera: Pyralidae) at a research station in Antarctica

AbstractWe report the first formal record of the Indian meal moth Plodia interpunctella from a location within the Antarctic Treaty area, with the capture of a live adult male within the Brazilian Comandante Ferraz research station on King George Island, South Shetland Islands. This species is a well-known pest of stored products and is widely recorded in synanthropic situations such as food stores globally. No other adults or immature stages have been observed on the station. While there is no suggestion that P. interpunctella could survive or establish in the natural environment beyond the station, this observation highlights the ever-present threat of unintended anthropogenically assisted transfer of non-Antarctic species into human facilities on the continent, with some such species proving extremely difficult to eradicate if they successfully establish within these facilities.

The Impacts of Climate Change on the Potential Distribution of Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) in China.

Simple SummaryPlodia interpunctella (Hübner) is an important grain storage pest in China that is distributed in almost every province and that has caused huge economic losses. In this study, we adjusted the biological parameters of the Indian grain borer and then used the CLIMEX model to predict the detailed potential distribution of P. interpunctella in China under current and future conditions. Under historical climatic conditions, the central, northeastern, and southern regions of China are highly suitable habitats for it. Because of temperature change in the future climate, suitable habitats will increase in the eastern part of Qinghai and will decrease in the mid-eastern, northeastern, and southeastern parts of China. This study provides important information for controlling the further spread of the Indian corn borer in China.The Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is a notorious stored-grain pest that can be found in most parts of China. The corpses, excretions, and other secretions of P. interpunctella larvae cause serious grain pollution, seriously affecting the nutritional and economic value of stored grain in China. To elucidate the potential distribution of P. interpunctella in China, we used the CLIMEX 4.0 model to project the potential distribution of the pest using historical climate data (1960–1990) and estimated future climate data (2030, 2050, and 2070). Under the historical climate situation, P. interpunctella was distributed in most areas of China, and its highly favorable habitats account for 48.14% of its total potential distribution. Because of temperature change in the future climate, suitable habitats will increase in the eastern part of Qinghai and will decrease in the mid-eastern, northeastern, and southeastern parts of China. Under these scenarios, the area of this pest’s highly favorable habitat will be reduced by 1.24 million km2, and its proportion will decrease to about 28.48%. These predicted outcomes will help to distinguish the impact of climate change on the potential distribution of P. interpunctella, thereby providing important information to design early forecasting and strategies to prevent pest harm to stored grain.

The first evidence of the Indian meal moth (Plodia interpunctella) interaction with the silicone moulds

The Indian meal moth (Plodia interpunctella, Lepidoptera) is a common insect species and well-known, widespread kitchen pest. This paper reports the results of their interaction with silicone baking moulds and the evidence for synthetic material decomposition. The obtained fibres exhibited a high level of purification and were characterized by Raman spectroscopy. The reported interaction should be further studied from the biological perspective, as it can be crucial for the remediation of silicones or other synthetic polymers in the environment.

Development of DNA Melt Curve Analysis for the Identification of Lepidopteran Pests in Almonds and Pistachios.

Simple SummaryAlmonds and pistachios are fed upon by a diverse assemblage of lepidopteran insects, several of which are economically important pests. Unfortunately, identification of these pests can be difficult, as specimens are frequently damaged during collection, occur in traps with non-target species, and are morphologically similar up to their third instar. Here, we present a quantitative PCR based melt curve analysis for simple, rapid, and accurate identification of six lepidopteran pests of almonds and pistachios: navel orangeworm, peach twig borer, oriental fruit moth, obliquebanded leafroller, raisin moth, and Indian meal moth. We demonstrate that the dissociation or the “melt” temperature(s) of a 658 bp section of cytochrome c oxidase subunit 1 provides unambiguous species level identification of these six species and is reproducible in field specimens collected following conventional orchard practices. The melt curve’s simplicity allows it to be performed in any basic molecular biology laboratory with a quantitative PCR.Almonds and pistachios are fed upon by a diverse assemblage of lepidopteran insects, several of which are economically important pests. Unfortunately, identification of these pests can be difficult, as specimens are frequently damaged during collection, occur in traps with non-target species, and are morphologically similar up to their third instar. Here, we present a quantitative PCR based melt curve analysis for simple, rapid, and accurate identification of six lepidopteran pests of almonds and pistachios: navel orangeworm (Amyelois transitella), peach twig borer (Anarsia lineatella), oriental fruit moth (Grapholita molesta), obliquebanded leafroller (Choristoneura rosaceana), raisin moth (Cadra figulilella), and Indian meal moth (Plodia interpunctella). In this approach, the dissociation (melt) temperature(s) of a 658 bp section of cytochrome c oxidase subunit 1 was determined using quantitative PCR (qPCR). Within these six species, the distribution and the number of melt peak temperatures provide an unambiguous species level identification that is reproducible when unsheared DNA can be extracted. The test is robust across a variety of sampling approaches including insects removed from sticky card traps, museum specimens, and samples that were left in the field for up to 7 days. The melt curve’s simplicity allows it to be performed in any basic molecular biology laboratory with a quantitative PCR.

Hermetic Storage of Shelled Peanut Using the Purdue Improved Crop Storage Bags1

ABSTRACT Low oxygen or hermetic storage has been successfully used to store several commodities such as corn (Zea mays L.), cowpea (Vigna Savi), cocoa (Theobroma cocao), coffee (Coffea L.), and rice (Oryza sativa L.). However, previous research using hermetic storage for peanut or groundnut (Arachis hypogaea L.) had mixed results. Research was conducted to determine the effect on aflatoxin contamination, seed germination, and oil chemistry of shelled peanut hermetically stored in the Purdue Improved Crop Storage (PICS) bags for up to 12 months. A 2 × 4 factorial study included 1) normal and high oleic peanut, 2) two initial moisture contents by four storage treatments. The four storage treatments were 1) burlap bags as the control, 2) PICS bags, 3) PICS bags with air extracted by vacuum, and 4) PICS bags with sachets of chlorine dioxide (ClO2) dry fumigant added. There were three replications of each treatment combination. Peanut was stored in an area maintained at a temperature above 21C. The initial seed germination of the normal oleic and high oleic peanuts was 77 and 80%, respectively. Initial aflatoxin concentration in all peanut was less than 2 μg/kg. Bags were opened, sampled, and resealed at 60, 159, 249, and 301 d of storage. Approximately half of the 12 burlap bags suffered significant rodent damage, and all had significant infestation by Indian meal moth (Plodia interpunctella). Only 4 PICS bags had rodent damage with damage limited to the outer polypropylene bag. There were no live insects in the PICS bags. Seed germination decreased for all samples to an average of 6.3%. Peanut stored in the burlap bags had an average germination of 19.2% compared to 2.1% for peanut stored in PICS bags. The aflatoxin concentration in one of the burlap bags with normal oleic peanuts was 75 μg/kg, and one of the PICS bags with high oleic peanuts had an aflatoxin concentration of 12 μg/kg. The remaining samples had aflatoxin below the detectable limit of 2 μg/kg.

Application of Ozone against the Larvae of Plodia interpunctella (Hübner) and Its Impacts on the Organoleptic Properties of Walnuts

One of the most important products grown in Iran is walnut (Juglans regia L.), but it can be threatened by storage pests such as insects. Ozonation is an environmentally friendly method for killing pest insects; accordingly, ozone efficacy in the control of a pest species of walnut, Indian meal moth (Plodia interpunctella (Hübner)), was assessed in this research. The selected walnut samples were infested with larvae of Indian meal moth and then subjected to various combinations of ozone concentration (3, 4.5, and 6 ppm) and exposure time (20, 30, 40, and 50 min). After exposure to the treatment combinations, larval mortality rates and changes to the sensory properties (color, taste, smell, crispness, stiffness, and overall acceptability), indicating consumer preference, of the walnuts were evaluated. Our results revealed enhanced mortality rates of P. interpunctella with an increase in both ozone concentration and exposure time: 99% mortality was recorded at the concentration and exposure time of 6 ppm and 50 min, respectively. Sensory assessments of the samples showed that ozone treatments had no significant impacts on the color, taste, crispness, stiffness, and overall acceptability of the product. Also, few changes were recorded for its smell, which could be improved over time after being exposed to the air. We conclude that application of higher ozone concentrations might provide acceptable levels of insect pest control for stored walnuts with no associated reduced trade-off for their quality attributes.

Persistence of Mating Suppression of the Indian Meal Moth Plodia Interpunctella in the Presence and Absence of Commercial Mating Disruption Dispensers.

Simple SummaryA novel assay system was used to facilitate replicated studies examining the impact of commercial mating disruption dispensers on Plodia interpunctella. Both direct and indirect exposure to passive mating disruption dispensers for as little as 2 h suppressed mating throughout the rest of a 10 h scotophase. This is the first direct evidence that for P. interpunctella, transient exposure to commercial mating disruption dispensers is sufficient to suppress male orientation to females without re-exposure to the mating disruption dispensers. An improved understanding of mechanisms for mating disruption can improve both development of future products and how current products are used.The Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), is controlled by commercial mating disruption dispensers using passive release to emit high concentrations (relative to females or monitoring lures) of their principal sex pheromone component, (9Z,12E)-tetradecadienyl acetate. Since P. interpunctella is sexually active throughout the scotophase, an assay system was developed to determine the importance of direct interaction of the male with the dispenser, and whether exposure to mating disruption early in the night is sufficient to suppress mating throughout the night. Exposure to mating disruption dispensers in the mating assay chamber for the first two hours of a 10-h scotophase significantly reduced mating when females were introduced four hours later. Mating was also reduced to a lesser degree in a concentration-dependent manner based solely on re-emission of pheromone, and when males were exposed outside the mating assay chamber. These results indicate that the commercial mating disruption dispensers can suppress mating throughout the night based on interaction with the dispenser early in the night. Desensitization resulting from attraction to a high-concentration pheromone source is important to this suppression, but other factors such as re-emission from the environment may also have a role. These observations imply a non-competitive mechanism for P. interpunctella with the product studied, and suggest that effectiveness of the mating disruption dispenser might be augmented by using them in conjunction with another formulation such as an aerosol or micro-encapsulated product.

Differentiated transcriptional regulation before and after death in Indianmeal moth Plodia interpunctella

Abstract Genes differentially regulate transcription processes to maintain biological activities throughout the life of an organism. However, little is known about their fate after organismal death. The Indianmeal moth Plodia interpunctella is a global pest insect that infests stored and manufactured agricultural products. We examined the changes in mRNA levels of nine genes associated with development, stress, and host defense mechanisms before and after death in P. interpunctella adults using quantitative real-time reverse transcription PCR. The results revealed that the transcription rates among genes were not consistent in relation to death. The mRNA levels of hsp25, hsp70, grp78, hsp90, EcR, USP, ProPO, and Tpx gradually increased until the time of death and remained high for at least 5 days. However, βgrp level continuously declined at the time of death. Our results showed that transcriptional activity was maintained after death, which suggests the presence of cellular responses during the post-mortem period.

Investigating the effect of starvation and various nutritional types on the hemocytic profile and phenoloxidase activity in the Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae)

The defense mechanisms of the insects are based on involvement of the hemocytes and phenoloxidase. Hemocytes are the basic component of the cellular immunity and phenoloxidase as the part of prophenoloxidase (PPO) cascade is the component of both humoral and cellular defense. Nutrition as well as starvation and attack by any organisms can modify these parameters of the innate immunity. In the current study, the effects of the stresses imposed by the starvation or different types of diets were investigated on the important immunity aspects of the indian meal moth larvae. Results showed a decline in the total hemocyte count in hemolymph with the increase in the starvation duration. In the first test, 5th instar larvae were starved for three time intervals including 24, 48, and 72 h and then, the changes in hemocyte number and phenoloxidase activity were studied. In the second experiment, the larvae bred on four diets including diet (A) walnut, diet (B) pistachio, diet (C) pea and raisin, and diet (D) artificial diets were used. The total number of the hemocytes and percentage of each hemocyte were also considered. Larvae were kept in an incubator set at a temperature of 25 ± 1 °C with 45 % of relative humidity (RH), and a constant photoperiod of 14:10 h (L:D) during the tests. The number of the plasmatocytes, one the main immune cells was sharply decreased with prolongation of the starvation duration and finally, their number reached by 134.04 ± 25.25 mm3 of hemolymph. The number of the granulocytes was also decreased significantly 72 h post-starvation than other treatments. The prohemocytes as the stem cells were initially increased within 24 h, and they were decreased later. The oenocytoids as the key cells involved in the phenoloxidase activity were initially increased significantly within 24 h of starvation compared to the control, but they were decreased significantly after 48 and 72 h reaching the same amount as the controls. Results revealed that the types of the consumed diet influenced the number of cells and phenoloxidase activity. The highest total hemocyte count was related to the diet (C) pea and raisins (2158.18 ± 172.5 mm3), and the lowest was observed in the larvae fed on the pistachios (924 ± 78.33 mm3). The number of plasmatocytes, granulocytes, and oenocytoids was the highest in those larvae fed on the diet (C) pea and raisin and diet (D) artificial diet, respectively but the lowest numbers were observed for other treatments. The number of prohemocytes in the larvae fed on different diets did not differ significantly. The phenoloxidase activity was significantly reduced in the fifth instar larvae following starvation. The highest activity of phenoloxidase in feeding treatments was observed in those larvae fed on the artificial diet while the lowest activity was observed in the pistachio-fed larvae. Thus, the amount and type of the diet and the stresses including starvation can determine the immune response of the insects against the entomopathogens.

Development and diapause induction of the Indian meal moth, Plodia interpunctella (H\xfcbner) (Lepidoptera: Pyralidae) at different photoperiods

Diapause concerns the fascinating phenomenon in the biology of insect development which allows better understanding the local adaptation and phenotypic plasticity to seasonal variations in environment. There is lot of reasons to carry out the research on diapause both for fundamental and applied sciences. Photoperiod is one of the main environmental cues followed by insects to predict the forthcoming seasonal changes and to adapt these changes in their life-history traits. Thus, the effect of different photoperiod regimes on development and diapause induction of larvae of the Indian meal moth Plodia interpunctella (Hübner) was evaluated at a constant temperature of 17 °C. Development was significantly faster at a photoperiod of 12:12 light:darkness (L:D) than at 8:16, 10:14, 14:10 and 16:8 L:D. A photoperiod of 12:12 (L:D) induced most larvae (≥ 71%) to enter diapause, while this percentage was slightly lower (60%) at both shorter(8 h) and longer (16 h) day lengths (50%). The different photoperiod regimes did not affect the percentage of adult emergence. Fat and protein composition of the diapausing larvae differed significantly among treatments as well as between diapausing and non-diapausing larvae. Larvae developing from 8:16 (L:D) contained the maximum amount of protein (36.8%) compared to other regimes, while the minimum amount (21.0%) was noted in larvae that developed at 16:8 (L:D). Six types of fatty acids were detected in the larvae: myristic acid (methyl tetradecenoate), palmitoleic acid (9-hexadecenoic acid, methyl ester), palmitic acid (hexadecenoic acid, methyl ester), linoleic acid (9, 12-Octadecadienoic acid (Z, Z), methyl ester), oleic acid [9-octadecenoic acid, methyl ester (E)] and stearic acid (octadecanoic acid, methyl ester). The results also reveal that the percent of fatty acids detected in the diapausing larvae varies significantly and the same trends imply in the interaction of fatty acid and photoperiod regimes. Moreover, three quarters of the total variance was accounted for by the Principal Component Analysis (PCA) of the fatty acids. Different proportions of fatty acids were noted among treatments, suggesting that photoperiod influences a number of key biological traits in P. interpunctella, much more than the percentage of the diapausing larvae per se.