Preoviposition Period Research Articles

Sublethal effects of spinetoram and emamectin benzoate on key demographic parameters of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) under laboratory conditions.

Fall armyworm (FAW) Spodoptera frugiperda, is a serious invasive pest of many crops that causes huge economic losses to agricultural commodities. Insecticides are employed for the management of S. frugiperda. In this study, we investigated the impact of sublethal concentration (LC10) and low lethal concentration (LC30) of spinetoram and emamectin benzoate on S. frugiperda using two-sex life table method. Bioassay results revealed that emamectin benzoate exhibited more toxicity on the 3rd instar of S. frugiperda (LC50 8.35 × 10-4mgL-1) than spinetoram (LC50 2.6 × 10-2mgL-1) after 48h exposure. The total longevity, adult pre-ovipositional period (APOP) and total pre-ovipositional period (TPOP) were prolonged, while pre-adult survival rate and fecundity were reduced at both concentrations of spinetoram and emamectin benzoate. Moreover, the key demographic parameters, including the intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R0), were significantly lower in insecticide treated groups as compared to untreated insects. Our findings revealed that the sublethal and low lethal concentrations of both insecticides reduce the survival and reproductive capability of S. frugiperda. These results would be useful to assess the overall effect of both insecticides on S. frugiperda and can provide important implications for the rational utilization of insecticides against S. frugiperda.

BIOMORPHIC PARAMETERS OF FALL ARMYWORM, SPODOPTERA FRUGIPERDA (LEPIDOPTERA: NOCTUIDAE) ON MAIZE UNDER LABORATORY CONDITION

Fall armyworm, Spodoptera frugiperda is an invasive polyphagous pest that causes heavy damage to several agricultural crops especially maize and rice in the world. This pest attacks on more 353 host plants species, especially belong to poaceae family. The knowledge of developmental duration of FAW (S. frugiperda) is very necessary for predicting increases in field population and determining the appropriate timing and control techniques. For this purpose, the current research was conducted. The mean of incubation period was 3.55 ± 0.49 from 2 to 4 days. The average duration of first, second, third, fourth, fifth, sixth larval instar and pupa was 2.78 ± 0.43, 2.94 ± 0.53, 2.64 ± 0.91, 2.58 ± 0.36, 2.96 ± 1.95, 6.01 ± 0.41, and 8.32 ± 0.37 days, respectively. The average length of first, second, third, fourth, fifth, and sixth larval instar was 1.38 ± 0.56, 3.29 ± 0.68, 5.63 ± 0.73, 9.76 ± 0.54, 14.71 ± 1.89, and 30.11 ± 2.88 mm, respectively. The average width of first, second, third, fourth, fifth, and sixth larval instar 0.24 ± 0.10, 0.58 ± 0.09, 1.76 ± 0.22, 3.10 ± 0.26, 4.85 ± 0.31, and 5.74 ± 0.30 mm, respectively. Female was long lived as compared to male. The average preoviposition, oviposition and post oviposition period of adult was 1.02 ± 0.61, 3.11 ± 0.69, and 4.51 ± 0.74 days, respectively. The total life period of male and female was 33-45 and 38-50 days, respectively. The knowledge of developmental duration of FAW (S. frugiperda) will be helped in predicting the pest population in field and determining the suitable or best strategy to control this pest.

Trade-Offs between Temperature and Fitness in Euschistus heros (Fabricius) (Hemiptera: Pentatomidae): Implications for Mass Rearing and Field Management

The brown stink bug, Euschistus heros (Fabricius, 1798) (Hemiptera: Pentatomidae), is one of the most abundant soybean stink bug pests in Brazil. Temperature is a key factor that affects its development and reproduction, and fluctuating temperatures may impact the development and reproduction of E. heros differently from those under constant temperatures. The objective of this study was to evaluate the influence of constant and fluctuating temperature on the biological characteristics of E. heros in three successive generations. Treatments consisted of six constant temperatures (19 °C, 22 °C, 25 °C, 28 °C, 31 °C and 34 °C) and four fluctuating temperatures (25:21 °C, 28:24 °C, 31:27 °C, and 34:30 °C) evaluated for three successive generations. Second-stage nymphs were evaluated daily, and after they reached the adult stage, they were separated by sex, and the individual weight (mg) and pronotum size (mm) were recorded. After pair formation, eggs were collected to evaluate the pre-oviposition period, total number of eggs, and egg viability. The duration of the nymphal stage was reduced with an increase in both constant and fluctuating temperatures; however, at constant temperatures of 19 °C, 31 °C and 34 °C and fluctuating temperatures of 28:24 °C, there was no reproduction in adults. The base temperature and total degree day requirement for nymphal development were 15.5 °C and 197.4 dd, respectively. Pre-oviposition period (d), number of eggs per female, and viability of eggs (%) were affected by temperature across the generations. The multiple decrement life table analysis revealed that mortality was highest during the molting of the second-stage nymphs. These findings have important implications for E. heros' laboratory mass-rearing programs and for its management in fields.

Risk assessment of predatory lady beetle Propylea japonica's multi-generational exposure to three non-insecticidal agrochemicals

The effects of non-insecticidal agrochemicals on pest natural predators remain largely unexplored except bees and silkworm. The herbicide quizalofop-p-ethyl (QpE), fungicide thiophanate-methyl (TM), and plant growth regulator mepiquat chloride (MC) have been extensively applied as non-insecticidal agrochemicals. Here, we systematically evaluated multiple effects of these 3 non-insecticidal agrochemicals on three generations of Propylea japonica, an important agroforestry predatory beetle, including the effects on its development, reproduction, enterobacteria, and transcriptomic response. The results showed that QpE exhibited a hormetic effect on P. japonica, thus significantly increasing the survival rate of generation 2 (F2) females, generation 3 (F3) females, and F3 males and body weight of F3 males. However, three successive generations exposed to TM and MC had no significant effect on longevity, body weight, survival rate, pre-oviposition period, and fecundity of P. japonica. Additionally, we investigated the effects of MC, TM, and QpE exposure on gene expression and gut bacterial community of F3 P. japonica. Under MC, TM, and QpE exposure, the overwhelming genes of P. japonica (99.90 %, 99.45 %, and 99.7 %) remained unaffected, respectively. Under TM and MC exposure, differentially expressed genes (DEGs) were not significantly enriched in any KEGG pathway, indicating TM and MC did not significantly affect functions of P. japonica, but under QpE exposure, the expression levels of drug metabolism-related genes were down-regulated. Although QpE treatment did not affect gut dominant bacterial community composition, it significantly increased relative abundances of detoxification metabolism-related bacteria such as Wolbachia, Pseudomonas and Burkholderia in P. japonica. However, TM and MC had no significant effect on the gut bacterial community composition and relative abundance in P. japonica. This study revealed for the first time the mechanism by which P. japonica might compensate for gene downregulation-induced detoxification metabolism decline through altering symbiotic bacteria under QpE exposure. Our findings provide reference for the rational application of non-insecticidal agrochemicals.

Impact of vitellogenin based dsRNA feeding on reproductive biology of red palm weevil, Rhynchophorus ferrugineus (Olivier), (Coleoptera: Dryophthoridae) under laboratory conditions

ObjectiveRed palm weevil, Rhynchophorus ferrugineus is a crucial pest of date palm, in the Kingdom of Saudi Arabia including several other palm producing countries of the World. The vitellogenin gene play very important role for oocytes development in all oviparous animals. Recently, we have silenced the vitellogenin gene by injecting the RfVg-based dsRNA and proved that RNAi technology can be used to manage red palm weevil. The main challenge in RNAi-based plant protection methods is selecting a suitable tactic for successfully delivering the dsRNA. MethodsIn the present study, 9-10th instar red palm weevil larvae were provided with Vg-based dsRNA in diet and as drops to determine its effects on red palm weevil reproductive traits, such as pre-oviposition period, fecundity, oviposition period, post oviposition period, eggs size, and female and male life span. ResultsResults demonstrated that the RfVg gene function was successfully suppressed using Vg-based RNAi. When applied via drops, resulting in a significant decline in red palm weevil eggs hatchability and Vg expression measured by quantitative real time Polymerase chain reaction. However, when applied via diet, Vg-based dsRNA did not show any significant effect on fecundity, oviposition period, post oviposition period, eggs size, and female and male life span. ConclusionsBased on present overall results and our previous findings, along with the documented information, we can conclude that Vg-based RNAi has a high potential for use as a target specific and eco-friendly technique for the sustainable control of this crucial pest.

Effects of supplemental nutrients on ovarian development and oviposition in Conogethes punctiferalis (Lepidoptera: Crambidae).

Conogethes punctiferalis is a serious pest in China affecting a wide variety of field crops, fruits, and forest trees. Many insects require supplemental nutrients after emergence to compensate for insufficient nutrients at the larval stage. In this study, to better understand the determinants of C. punctiferalis survival and reproduction, the impact of supplemental nutrition was examined. In particular, the effects of 11 treatments (5% sucrose, 10% sucrose, 15% sucrose, 5% sophora honey, 10% sophora honey, 15% sophora honey, 5% wild honey, 10% wild honey, 15% wild honey, distilled water, and blank control) on adult longevity and oviposition were evaluated, with detailed morphological analyses of ovarian development in the 10% sucrose, distilled water, and blank control groups. Conogethes punctiferalis required supplementary nutrition after emergence. Supplementary nutrition improved fecundity (number of eggs laid) and longevity, and 10% sucrose water had the greatest effects. The preoviposition period and oviposition period of C. punctiferalis females were longer, and the numbers of eggs in female ovarian tubes and eggs laid by females were higher in the 10% sucrose water group than in other groups. Females supplemented with distilled water laid a small number of eggs. Without nutrient supplementation, females did not lay eggs. In conclusion, supplemental nutrition was beneficial for ovarian development in female moths, prolonging the oviposition period and lifespan, and was an important factor affecting population dynamics. These results lay a foundation for further analyses of the nutritional requirements for C. punctiferalis in the field and provide a reference for indoor population feeding.

Prey suitability and life table analysis of Amblyseius swirskii and Amblyseius aerialis (Parasitiformes: Phytoseiidae) on Panonychus citri (Acariformes: Tetranychidae) and Phyllocoptruta oleivora (Acariformes: Eriophyidae)

Phytoseiid mites are important predators of several pests including mites and are widely used in enclosed and open crop production systems. We evaluated two phytoseiid species, one that is commercially available (Amblyseius swirskii), and a species found in Florida citrus (A. aerialis), against pest mites Panonychus citri and Phyllocoptruta oleivora. These pests cause significant losses to citrus grown in traditional orchards and enclosed systems such as Citrus Under Protective Screen (CUPS). CUPS is a new undercover system being implemented to produce citrus free of Huanglongbing (HLB) disease and its vector psyllid. Development period, longevity, reproduction, and life table parameters of the two predatory mites were evaluated under laboratory conditions at 22 ± 2 °C and 60 ± 5% RH. Phyllocoptruta oleivora was not suitable for both predatory mites even to complete development through protonymph stage. When fed on P. citri, A. swirskii developed faster than A. aerialis, (8.9 vs. 10.2 days, respectively) and exhibited a shorter pre-oviposition period than A. aerialis (3.6 vs. 5.5 days, respectively) and a longer oviposition period (31.9 vs. 24.1 days, respectively). Fecundity and oviposition rate were also higher for A. swirskii than A. aerialis averaging 43.4 vs. 17.3 eggs/female, respectively, and 1.4 vs. 0.7 eggs/female/day, respectively. The positive effects of feeding on P. citri also improved several life table parameters of A. swirskii compared to A. aerialis. The intrinsic rate of increase, finite rate of increase, and net reproductive rate were all significantly higher for A. swirskii (1.173, 0.16, and 32.52, respectively) than A. aerialis (1.105, 0.10, and 10.71, respectively). Findings suggest that both predatory mites benefited from feeding on P. citri and will be useful for their production and implementation in citrus pest management particularly against P. citri.

Insecticidal potential of organic extracts of Calotropis procera to Spodoptera frugiperda

This study evaluated the toxic effects of organic extracts of Calotropis procera leaves on the survival, development, and reproduction of Spodoptera frugiperda. Solutions of crude methanol extract and hexane and methanol fractions of C. procera leaves were added at 1.15% and 2.14% concentrations to the artificial diet of S. frugiperda. The mortality and duration of larval and pupal phases, weights of female and male pupae, deformations of pupae and adults, the reduction of adults able to reproduce, pre-oviposition and oviposition periods, the number of postures per female, and the fecundity and fertility of S. frugiperda females were also evaluated. The extracts harmed the survival, development, and reproduction of S. frugiperda. The ingestion of extracts and fractions by caterpillars affected adults by decreasing the oviposition period, the number of postures, fecundity, and fertility. The crude MeOH extract at a 2.14% concentration harmed the evaluated parameters of the insect, except for pupal mortality, female pupae weight, and pre-oviposition period. The MeOH fraction at 2.14% caused a 50.0% mortality of caterpillars and 16.0% deformation in pupae and 33.0% in adults, reducing by 72.0% the population able to reproduce. The MeOH fraction at the 2.14% concentration caused 25.0% and 38.0% of pupal mortality and deformation, respectively. Calotropis procera has promising insecticidal properties for a biological insecticide, a convenient and sustainable strategy for protecting plants against S. frugiperda.

Effects of chlorantraniliprole on the life history traits of fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae).

Introduction: Spodoptera frugiperda is an important nomadic agricultural pest with a diverse host range and resistance against several insecticides. The current study investigated the life history traits of two strains of the field-collected population against chlorantraniliprole using an age-stage two-sex life table. Method: For this, we established the chlorantraniliprole-susceptible (Crp-SUS G12), and chlorantraniliprole-reduced susceptible (Crp-RES G12) strains derived from the sixth generation of the QJ-20 population having a resistance ratio (RR) of 10.39-fold, compared with the reported susceptible population. Results: The results showed that the chlorantraniliprole-reduced susceptible strain attained a 4.0-fold RR, while the chlorantraniliprole-susceptible strain attained an RR of 0.85-fold, having overlapped fiducial limits (FLs) with the referred susceptible baseline. Meanwhile, the present study revealed that the development time of the susceptible strain was significantly longer than that of the reduced susceptible strain. Similarly, the mean longevity, adult pre-oviposition period (APOP), and total pre-oviposition period (TPOP) of the female chlorantraniliprole-susceptible strain were considerably longer than those of the female chlorantraniliprole-reduced susceptible strain. Contrarily, the population parameters, including the intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (R), of the chlorantraniliprole-susceptible strain were considerably lower than those of the chlorantraniliprole-reduced susceptible strain, while the mean generation time (T) of the chlorantraniliprole-susceptible strain was substantially longer than the chlorantraniliprole-reduced susceptible strain. The age-stage characteristic survival rate (s xj ) and age-stage characteristic life expectancy (e xj ) of the chlorantraniliprole-susceptible strain were longer than those of the chlorantraniliprole-reduced susceptible strain, but the age-stage-specific reproductive value (v xj ) of the chlorantraniliprole-susceptible strain was shorter than that of the chlorantraniliprole-reduced susceptible strain. Moreover, the contents of vitellogenin (Vg) and VgR in the chlorantraniliprole-reduced susceptible strain were higher than those in the chlorantraniliprole-susceptible strain. Discussion: These findings showed that reducing susceptibility to chlorantraniliprole promoted population growth in S. frugiperda. Therefore, this study could provide conceptual support for the integrated pest management (IPM) approach to control S. frugiperda in the field.

Life Table Study of Fall Armyworm (Spodoptera frugiperda) (Lepidoptera: Noctuidae) on Three Host Plants under Laboratory Conditions

After being discovered in Taiwan for the first time in June 2019, the polyphagous invasive fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae), has since spread throughout the entire nation. In Taiwan, this insect has a significant impact on the quality and output of wheat, corn, sorghum, and millet. It may further infest more crops in Taiwan due to its diverse range of hosts and alternate hosts. Maize and other staple crops have already been the subject of several study. The biology of FAW has not yet been studied in relation to the alternative hosts, particularly those commonly found in Taiwanese farmlands. Therefore, this study proposed to investigate the effects of napier grass (Pennisetum purpureum), natal grass (Melinis repens), and sunn hemp (Crotalaria juncea) on the development, reproduction, survivorship, and population growth of FAW under laboratory conditions. According to the results, the developmental duration was considerably the shortest when FAW was reared on sunn hemp while the longest on natal grass. Furthermore, female adults reared on napier grass had a longer adult pre-oviposition period, total pre-oviposition period, oviposition period, longevity, highest fecundity, and highest net reproductive rate (Ro: 465.12). Among the tested three alternative host plants evaluated, sunn hemp had the highest intrinsic rate of increase (r: 0.1993), finite rate of increase (λ: 1.2206), and shortest mean generation time (T: 29.98). Therefore, this study suggests that all hosts plants can contribute to the development and outbreak of this pest in the absence of its primary host; however, sunn hemp was a relatively more suitable host plant for this insect. The possibilities for the FAW's growth and development vary depending on the host plant. Thereby, all potential host plants in the area should be extensively examined while developing an IPM program against FAW.

In vitro life table of the storage mite Tyrophagus putrescentiae (Acari: Acaridae)

Introduction: The mite Tyrophagus putrescentiae is a common contaminant of stored products and an important pest in plant tissue culture laboratories, because they diseminate fungi and bacteria. Objective: To describe the reproduction and life table of T. putrescentiae in vitro. Methods: We reared the mites with its associated fungus Leptosphaerulina sp., recording growth and development every 12h. Results: The duration of the egg, larva, protonymph, and tritonymph stages of cohort 1 was 4,52; 1,57; 1,37 and 1,29 days (cohort 2: 4,54; 1,44; 1,31 and 1,45 days, respectively). Cohort 1 periods of pre-oviposition, oviposition and post-oviposition were 1,86; 7,21 and 1,35 days (most cohort 2 individuals did not reach maturity). The intrinsic rate of natural increase (rm) was 0,11 individuals per female per day, the net reproduction rate (Ro) was 29,21; the generation time was 29,47 days, and the finite rate of increase (λ) was 1,12 times per female per day. Conclusion: Under the typical laboratory conditions, T. putrescentiae can multiply its initial population in a single day, which explains the population explosions observed in these laboratories.

Identification and Characterization of Rhipicephalus microplus ATAQ Homolog from Haemaphysalis longicornis Ticks and Its Immunogenic Potential as an Anti-Tick Vaccine Candidate Molecule.

Although vaccines are one of the environmentally friendly means to prevent the spread of ticks, there is currently no commercial vaccine effective against Haemaphysalis longicornis ticks. In this study, we identified, characterized, localized, and evaluated the expression patterns, and tested the immunogenic potential of a homologue of Rhipicephalus microplus ATAQ in H. longicornis (HlATAQ). HlATAQ was identified as a 654 amino acid-long protein present throughout the midgut and in Malpighian tubule cells and containing six full and one partial EGF-like domains. HlATAQ was genetically distant (homology < 50%) from previously reported ATAQ proteins and was expressed throughout tick life stages. Its expression steadily increased (p < 0.001) during feeding, reached a peak, and then decreased slightly with engorgement. Silencing of HlATAQ did not result in a phenotype that was significantly different from the control ticks. However, H. longicornis female ticks fed on a rabbit immunized with recombinant HlATAQ showed significantly longer blood-feeding periods, higher body weight at engorgement, higher egg mass, and longer pre-oviposition and egg hatching periods than control ticks. These findings indicate that the ATAQ protein plays a role in the blood-feeding-related physiological processes in the midgut and Malpighian tubules and antibodies directed against it may affect these tissues and disrupt tick engorgement and oviposition.

Effects of food plants on life‐history traits of the newly invasive fall armyworm Spodoptera frugiperda

AbstractThe fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith; Lepidoptera; Noctuidae) has invaded Jiangxi Province, Southeast China for the past 3 years. Although the FAW displays a wide host range, its main host plants in Jiangxi Province are field corn. Understanding the population dynamics of the FAW on different host plants is critical for developing an appropriate control strategy. This study investigated the effects of food plants (corn, peanut, soybean and sugarcane) on life‐history traits of FAW and tested the leaf contents of the total flavonoids, reducing sugars, sucrose and C/N ratio of these host plants. We found that the FAW fed on corn leaves exhibited significantly shorter larval and pupal development times, larger body weight, higher growth rate, lower weight loss, smaller sexual size dimorphism, shorter preoviposition period and higher fecundity than those fed on peanut, soybean and sugarcane leaves. The FAW showed a protogyny phenomenon because the pupal development stage was significantly longer in males than females. Food plants changed the relationships between larval development time and pupal weight and between fecundity and longevity. The corn leaves showed significantly higher contents of reducing sugars and sucrose, lower content of the total flavonoids and a moderate C/N ratio compared with the other leaves, suggesting that the corn leaf tissues are more nutritious. Our results provide the most comprehensive information about the life‐history traits of this newly invasive pest. These findings may help us understand why the FAW mainly infests corn plants and may be critical for the development of strategies to predict infestation levels.

Different maize varieties have greater impact on Tetranychus urticae (Acari: Tetranychidae) than GE maize expressing Cry3Bb1 insecticidal protein

Genetically engineered (GE) maize expressing Bacillus thuringiensis Cry3Bb1 protein was developed to control Diabrotica spp. (Coleoptera: Chrysomelidae). However, Cry proteins have been reported to have effects on non-target arthropods. We therefore investigated whether the non-target pest Tetranychus urticae (Acari: Tetranychidae) was negatively affected by GE maize expressing the insecticidal Cry3Bb1 protein. Five treatments were used in the laboratory tests to determine the life history parameters of T. urticae on leaves of field-grown maize varieties: (1) GE maize MON 88017, (2) isogenic maize, (3) isogenic maize protected with the soil applied insecticide chlorpyrifos (Dursban 10G), and two unrelated varieties (4) Kipous and (5) PR38N86. Newly emerged T. urticae larvae were individually released on the upper surface of leaf discs placed on water saturated cotton wool. Immatures and adults survival, duration of developmental stages and female fecundity were recorded daily until T. urticae died. Age–stage, two-sex life table method and test for trends, revealed no significant differences in 13 of 18 studied parameters. The unrelated varieties Kipous and PR38N86 on one side and maize with the same genetic background, namely GE maize and isogenic maize with or without insecticide protection, on the other side, showed significant variations in male longevity, larval survival rate, preoviposition period, and fecundity. In addition to the differences between varieties, GE maize and insecticide-protected isogenic maize showed a substantial difference in age-specific fecundity, but not in the mean number of eggs laid by females.The obtained results do not indicate that consumption of Cry3Bb1 has negative effect on T. urticae and suggest that GE maize does not pose a risk with respect to the non-target mite pest T. urticae. The results may have implications for the approval and renewal of import and cultivation for GE crop in the European Union.

Lethal and Sublethal Effects of Mixed Pesticides on Tetranychus urticae Koch and its Predator Phytoseiulus persimilis

Abdou, D.A.M., M.M. Elbokl, A.E.M. Abd Elmageed and M.G. Habashy. 2023. Lethal and Sublethal Effects of Mixed Pesticides on Tetranychus urticae Koch and its Predator Phytoseiulus persimilis. Arab Journal of Plant Protection, 41(1): 40-47. https://doi.org/10.22268/AJPP-41.1.040047 Tetranychus urticae Koch is considered one of the most economically important pests on a wide range of crops in orchards worldwide. T. urticae control has been largely based on the utilization of acaricides. Sublethal effects of Romectin gold 32.8% SC (Abamectin 2.8% + Imidaclopride 30%) and AgriFlix 18.56% SC (Thiamethoxam 15.24% + Abamectin 3.23%) were studied on toxicity index and life-table parameters of T. urticae. LC25 concentration of Romectin gold and AgriFlix that were 0.0019 and 0.013 ppm, respectively, were utilized for sublethal studies. All acaricides showed a significant effect on T. urticae. Results obtained indicated that Romectin gold was the compound that had the higher effect on adult females of T. urticae and its predatory mite P. persimilis than AgriFlix. Sublethal concentrations of Romectin gold and AgriFlix may influence the durability of pre-adult stages, longevity, and biological parameters of T. urticae. The duration of life cycle of both females and males decreased significantly compared to the control with no significant effect between the two tested compounds. At the same time, Romectin gold produced the highest life cycle and life span. AgriFlix significantly decreased the pre-oviposition period with the lowest time of 1.10 days compared with 2.00 days for the control. To the contrary, Romectin gold had no significant effect on the preoviposition period. On the other hand, treatments with both Romectin gold and AgriFlix decreased significantly the oviposition period compared with the control. Romectin gold and AgriFlix significantly reduced the total number of eggs produced per female. AgriFlix acaricide decreased the total number and the daily rate of eggs produced by 73.36 and 65.05%, respectively. Results showed that exposure of females to sublethal concentrations of Romectin gold and AgriFlix reduced the net reproductive rate (R0), while intrinsic rate (rm) was increased compared to the control. Similarly, the finite rate of increase (exprm) for the control was significantly higher than that for Romectin gold and AgriFlix. Additionally, it was found that mean generation time (T) of the control was significantly shorter than that of Romectin gold and AgriFlix. Meanwhile, sex ratio was the same for control, Romectin gold and AgriFlix. Keywords: Sublethal effects, toxicity index, Life-table parameters, Abamectin, Imidaclopride and Thiamethoxam.

Biology of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) on Rice and Different Corn Varieties

Rice and corn are one of the most important crops in the Philippines. Several insect pests contribute to the losses and low yield of these crops. The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), was recently reported to cause economic damage to corn. Also, this insect consists of two genetically differentiated strains namely, the corn strain and the rice strain. This study was conducted in a laboratory conditions to evaluate the biological parameters of FAW on rice and corn varieties. Newly hatched larvae were fed such as the open pollinated variety (OPV), traditional variety, Macho F1 (hybrid), NK 6410 (genetically modified organism), and rice variety, RC 226. Duration of larva, prepupal, pupal, and larva-adult period, pre-oviposition, oviposition, and post-oviposition period, number of egg mass, fecundity, sex ratio, and survivability of larva to adult of different crops were evaluated. The results showed that the duration of development from egg to adult in Macho F1 and NK 6410 with an average duration of 24.58 and 24.66 d was significantly shorter than OPV, traditional variety, and rice variety, RC 226. The number of eggs laid by females reared on Macho F1, NK 6410, and OPV, with a mean of 1125.60, 1176.80, and 1049.40, respectively, were significantly greater than the traditional variety, tinigib, and rice RC 226. Different corn varieties and rice did not affect the male and female ratio, longevity, and survivability. The results of this study will provide insights into formulating management strategies for fall armyworm.

Biology and Morphometric Study of Okra Shoot and Fruit Borer &lt;i&gt;Earias Vitella&lt;/i&gt; (F.)

Investigations on biology of shoot and fruit borer (Earias vitella) on okra revealed that the freshly laid eggs were spherical, bluish green and finally become brownish. These measured 0.52± 0.02 x 0.51± 0.02 mm.The incubation period was 3.35± 0.76 days, and larval stage passed through four instars. The first,second, third and fourth instar was 2.16± 0.71, 1.43± 0.50, 2.26± 0.73 and 3.30±1.02 days, respectivelywith the total larval period of 9.13± 1.71 days. These were measured 1.77± 0.28, 2.60± 0.40, 6.45± 0.56 and14.15± 2.12 mm long respectively and 0.27± 0.03, 0.36± 0.08, 1.24± 0.07 and 3.23± 0.51 mm, respectivelyin breadth. The pre-pupa lasted for 1.43± 0.50 days. The male and female pupa measured 9.78± 0.46 mmand 3.14± 0.31 mm, 10.14± 0.69 mm and 3.37± 0.09 mm, respectively, with duration of 7.90± 0.92 and7.53± 0.50 days, respectively. The adult male measured 9.13± 0.41 mm in length and 21.02± 0.98 mm inbreadth with expanded wings. Whereas, female 10.71± 1.14 mm in length and 22.30± 1.48 mm in breadthwith expanded wings. The preoviposition, oviposition and post-oviposition periods were 1.50± 0.68, 6.00±1.33 and 4.30± 1.53 days, respectively. The fecundity was 265.00± 86.75 eggs/ female. The total lifecycleof male was 30.51± 6.00 days, while in female it was 32.60± 5.59 days.

Population Growth of Fall Armyworm, Spodoptera frugiperda Fed on Cereal and Pulse Host Plants Cultivated in Yunnan Province, China.

The fall armyworm, Spodoptera frugiperda is a major agricultural pest in China, and has migrated from its continuous breeding area to other parts of China. In our study, the biological behaviors of S. frugiperda fed on maize, wheat, barley, faba beans, and soya beans were evaluated in a growth chamber. Results indicated that maize-fed S. frugiperda larvae performed well, as evidenced by shorter larva-adult periods, adult pre-oviposition period (APOP), total pre-oviposition period (TPOP), and generation time (T), and a higher survival rate, intrinsic (r) and finite (λ) rate of increase, and net reproductive rate (Ro), However, S. frugiperda larvae performed weakly when fed barley and faba bean plants, as indicated by lower survival rates, r, and λ, and longer pre-adult period, TPOP, and T. A heavier pupal weight of both sexes was recorded on faba beans (0.202 g) and a lighter weight on barley (0.169 g). Fecundity was higher when fed faba beans and maize, and lower when fed wheat and barley. Thus, maize was the most optimal and barley was the least optimal host plant, followed by faba beans, for S. frugiperda larvae growth and development. This study enhances our knowledge of S. frugiperda in these host plants and can help in the design of management approaches.

Effect of different wheat cultivars on two sex life table parameters of Sitotroga cerealella (Lepidoptera: Gelechiidae)

Angoumois grain moth, Sitotroga cerealella (Olivier), reduces nutritional value, germination, and seed weight under storage conditions. The impacts of nine wheat cultivars including Azar 2, Baharan, Baran, Kohdasht, Mihan, Sadra, Sarang, Sardari, and Sirvan were evaluated on life table of S. cerealella under laboratory conditions. The results showed that the longest total immature stage of S. cerealella occurs in Sirvan and Mihan cultivars, whereas the shortest ones in Baran, Sardari, Kohdasht, and Sadra cultivars, respectively. The longest adult period occurs in Sadra, Kohdasht, and Sardari cultivars, and the shortest ones in Baharan, Mihan, Sarang and Sirvan cultivars, respectively. Wheat cultivars reveals significant impact on total pre-oviposition periods (TPOP), which are longer for S. cerealella fed on Sirvan cultivar than Sadra, Sardari and Kohdashet cultivars, respectively. The fecundity of S. cerealella increases in the case of insects fed on Sadra, Kohdashet, and Sardari cultivars, respectively, and decreases in Baharan, Mihan, Sarang, and Sirvan cultivars, respectively. The lowest gross reproductive rate (GRR) and net reproductive rate (R0) occur in Baharan, Mihan, Sarang, and Sirvan cultivars, respectively. Insects fed on Mihan, Baharan, Sarang, and Sirvan cultivars have the lowest intrinsic (r), and the finite (λ) rates of increase, respectively. In conclusion, Mihan, Baharan, Sarang, and Sirvan cultivars are potentially resistant against S. cerealella compared to other wheat cultivars. So, resistant cultivars may be a useful strategy for stored crop preservation and storage pest control.

Effect of temperature on the life table parameters and high-temperature lethality of Tyrophagus putrescentiae

The effects of five constant temperatures (16, 20, 24, 28, and 32 °C) on the development and reproduction of a serious stored products pest, Tyrophagus putrescentiae, fed on wheat bran were evaluated in the laboratory at 75% relative humidity. In addition, the efficacy of high temperatures (lethal temperatures) ranging from 39 to 49°C on the mortality of mobile stages of T. putrescentiae was investigated. The development time of different stages was decreased with increasing temperature, and total immature stages varied from 55.37 to 11.46 days. The pre-oviposition, oviposition, and post-oviposition periods, and female longevity all decreased with the temperature increasing. The longest oviposition period was 46.12 days at 16 °C. The female ratio increased from 52.4 to 68.8%. With the temperature. From 16 to 32 °C, the mean eggs deposited per day were 0.544, 0.994, 2.055, 3.034, and 1.421, respectively. The maximum fecundity (87.69 eggs per female) and the highest intrinsic rate of increase (rm) (0.194) were at 28 °C. In all mobile stages, mortality increased with the increase in temperature and exposure time. When temperatures ranged from 39.0 to 49.0 °C, the half-lethal time (LT50) of adult T. putrescentiae was 347.47, 124.38, 60.01, 33.66, 22.06, and 13.49 min, respectively, and it was shortened by half when the temperature was increased by 2 °C. The larvae were more sensitive to high temperatures than in other stages. Interestingly, the LT50 of adults was almost twice as LT50 of larvae under each temperature. The study suggests that temperature significantly affects the development, survival, and reproduction of T. putrescentiae, and heat treatment is an effective method to control this pest.