Identification and Characterization of an Antennae-Specific Glutathione S-Transferase From the Indian Meal Moth

Insect glutathione-S-transferases (GSTs) play essential roles in metabolizing endogenous and exogenous compounds. GSTs that are uniquely expressed in antennae are assumed to function as scavengers of pheromones and host volatiles in the odorant detection system. Based on this assumption, antennae-specific GSTs have been identified and functionally characterized in increasing number of insect species. In the present study, 17 putative GSTs were identified from the antennal transcriptomic dataset of the Indian meal moth, Plodia interpunctella, a severe stored-grain pest worldwide. Among the GSTs, only PiGSTd1 is antennae-specific according to both Fragments Per Kilobase Million (FPKM) and quantitative real-time PCR (qRT-PCR) analysis. Sequence analysis revealed that PiGSTd1 has a similar identity as many delta GSTs from other moths. Enzyme kinetic assays using 1-chloro-2,4-dinitrobenzene (CDNB) as substrates showed that the recombinant PiGSTd1 gave a Km of 0.2292 ± 0.01805 mM and a Vmax of 14.02 ± 0.2545 μmol·mg−1·min−1 under the optimal catalytic conditions (35°C and pH = 7.5). Further analysis revealed that the recombinant PiGSTd1 could efficiently degrade the sex pheromone component Z9-12:Ac (75.63 ± 5.52%), as well as aldehyde volatiles, including hexanal (89.10 ± 2.21%), heptanal (63.19 ± 5.36%), (E)-2-octenal (73.58 ± 3.92%), (E)-2-nonenal (75.81 ± 1.90%), and (E)-2-decenal (61.13 ± 5.24%). Taken together, our findings suggest that PiGSTd1 may play essential roles in degrading and inactivating a variety of odorants, especially sex pheromones and host volatiles of P. interpunctella.

Effficacy of fungicides, phytoextracts and cow urine against seed mycoflora of rice

Rice (Oryza sativa L.) is an important cereal crop belongs to the family Poaceae and native to south-east Asia. Rice crop needs a hot and humid climate. It is best suited to regions which have high humidity, prolonged sunshine and assured supply of water. It is an indispensable cereal essentially used in daily Indian meal in the form of dal-rice, roti, many south Indian foods and alcoholic beverages. Rice suffers heavy yield losses from diseases caused by fungi, bacteria and viruses many of which are carried through seed. Major seed borne fungi infecting rice includes Fusarium oxysporum, Fusarium moniliforme, Aspergillus niger, Aspergillus flavus, Alternaria padwickii and Curvularia lunata. Among all the fungicidal treatments, carbendazim + mancozeb gave minimum per cent seed mycoflora (5.00%). Among all the phytoextracts treatments, minimum per cent seeds showed mycoflroa was by neem (9.66%) and lowest mycelial growth and highest growth inhibition per cent found in 15% concentration cow urine.

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

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 Bags

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), and coffee (Coffea L.), rice (Oryza sativa L.). However, previous research using hermetic storage for peanut or groundnut (Arachis hypogaea L.) has 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 x 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 (ClO 2 ) 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.

Distribution and Occurrence of Vairimorpha plodiae (Opisthokonta: Microspora) in the Indian Meal Moth, Plodia interpunctella (Lepidoptera: Pyralidae) Populations: An Extensive Field Study

The Indian meal moth, Plodia interpunctella (Lepidoptera: Pyralidae) is one of the most important stored product pests. Fumigation plays a significant role in the management of insect pests in stored-products. However, the use of fumigants is problematic because of their effects on the environment and high costs. Entomopathogenic organisms are environmentally friendly control agents and suppress pest populations under natural conditions. In this study, distribution and occurrence of a microsporidian pathogen, Vairimorpha plodiae (Opisthokonta: Microspora) in the populations of P. interpunctella from 12 localities representing Turkey between 2019 and 2020 are presented for the first time by confirming its effectiveness on natural populations. The presence of the microsporidian pathogen was found in 11 of 12 (91.7%) populations. In total, 863 of 3,044 samples were infected by the pathogen. Infection mean was 28.4% for all populations. Our results showed that V. plodiae infection reached to a considerably high prevalence (88.77%) in P. interpunctella populations and varied from 5.1 to 88.7% between the populations. In addition, microsporidia infections have been identified throughout Turkey. We found that V. plodiae can infect all life stages of P. interpunctella. Totally, 623 (28.5%) of 2187 larvae, 14 (37.8%) of 37 pupae, 226 (27%) of 820 adults were found to be infected by the pathogen. There were considerable differences between the dead and living larvae. The microsporidian infection was found in 26 (11.6%) of 225 living larvae, whereas it was found in 595 (30.5%) of 1,952 dead larvae. These results confirm that the microsporidia pathogen has a high spreading potential in P. interpunctella populations and can be a natural biological suppression factor on pest populations.

Methyl Benzoate Is Superior to Other Natural Fumigants for Controlling the Indian Meal Moth (Plodia interpunctella)

The Indian meal moth, Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae), is an insect pest that commonly affects stored and postharvest agricultural products. For the control of insect pests and mites, methyl benzoate (MBe) is lethal as a fumigant and also causes contact toxicity; although it has already been established as a food-safe natural product, the fumigation toxicity of MBe has yet to be demonstrated in P. interpunctella. Herein, we evaluated MBe as a potential fumigant for controlling adults of P. interpunctella in two bioassays. Compared to the monoterpenes examined under laboratory conditions, MBe demonstrated high fumigant activity using a 1-L glass bottle at 1 μL/L air within 4 h of exposure. The median lethal concentration (LC50) of MBe was 0.1 μL/L air; the median lethal time (LT50) of MBe at 0.1, 0.3, 0.5, and 1 μL/L air was 3.8, 3.3, 2.8, and 2.0 h, respectively. Compared with commercially available monoterpene compounds used in pest control, MBe showed the highest fumigant toxicity (toxicity order as follows): MBe > citronellal > linalool > 1,8 cineole > limonene. Moreover, in a larger space assay, MBe caused 100% mortality of P. interpunctella at 0.01 μL/cm3 of air after 24 h of exposure. Therefore, MBe can be recommended for use in food security programs as an ecofriendly alternative fumigant. Specifically, it provides another management tool for curtailing the loss of stored food commodities due to P. interpunctella infestation.

Study on Assessing the Socio-economic Characters of Banana Cultivating Farmers in Coimbatore and Erode Districts of Tamil Nadu

Banana is a staple fruit in almost every Indian meal and also an important commercial crop that adds a considerable amount of dollar in country’s export revenues column. But in recent years the share is in decreasing trend due to some inevitable reasons. So understanding factors influencing banana exporting farmer’s especially among small and marginal farmers is a necessary one. This study tries to understand the socio-economic characteristics of banana farmers in Coimbatore and Erode district. 120 samples were selected randomly and well-structured interview schedule is used to collect data. The results show that most of the farmers were in the age group of 41 – 50 (32.50%) and are illiterate (28.33%) with farm experience of about 26-35 years (35%). Sample farmers largely live as a nuclear family (69.17%) and follow agriculture as a sole occupation (36.67%). Most of the sample farmers were marginal farmers (40.8%) with the annual income range of about 1 lakh to 3 lakh (35.83%). As many of them are small and marginal farmers and are illiterate, it is suggested to conduct number of training programs, tour visit and exhibition to increase the awareness about the export of banana.

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

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.

Development and diapause induction of the Indian meal moth, Plodia interpunctella (Hübner) (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.