Post-oviposition Periods Research Articles

Assessment of Biological Characteristics of Red Spider Mite (Tetranychus urticae) Koch on Brinjal

Red spider mite, Tetranychus urticae Koch passed through five stages viz., egg, larva, protonymph, deutonymph and adult with three short resting stages known as quiescent stages which termed as nymphochrysalis, deutochrysalis and teleiochrysalis. The incubation period of egg was 3.28 ± 1.10 days with 0.13 ± 0.01 mm diameter in size. The average length and breadth of larva, nymphochrysalis, protonymph, deutochrysalis, deutonymphs, teleiochrysalis, adult male and adult female stage were 0.14 ± 0.01 and 0.10 ± 0.01; 0.19 ± 0.01 and 0.12 ± 0.01; 0.20 ± 0.01 and 0.12 ± 0.01; 0.24 ± 0.02 and 0.13 ± 0.01, 0.29 ± 0.02 and 15 ± 0.02, 0.35 ± 0.03 and 0.18 ± 0.01, 0.43 ± 0.04 and 0.19 ± 0.01; and 0.47 ± 0.02 and 0.22 ± 0.01 mm, respectively. The mean duration of male and female larva, nymphochrysalis, protonymph, deutochrysalis, deutonymphs, teleiochrysalis and adult was 2.07 ± 0.73 and 2.36 ± 0.22, 0.58 ± 0.32 and 0.68 ± 0.22, 2.23 ± 0.35 and 2.92 ± 0.81, 0.70 ± 0.35 and 0.76 ± 0.39, 2.12 ± 0.44 and 2.56 ± 0.51, 0.77 ± 0.19 and 0.87 ± 0.37 and 7.12 ± 0.93 and 11.08 ± 0.86 days, respectively. Female of T. urticae occupied 2.48 ± 0.96, 5.32 ± 0.99 and 2.35 ± 0.84 days as pre-oviposition, oviposition and post-oviposition period, respectively. Total life period of male and female was 19.14 ± 2.06 and 23.85 ± 1.65 days, respectively. The average fecundity and hatching percentage were 47.60 ± 6.13 days and 91.11 ± 4.14 per cent, respectively with 1 : 2.50 sex ratio.

Multigenerational hormetic effects of different insecticides on Spodoptera frugiperda (J.E. smith) (Lepidoptera: Noctuidae)

To protect crops from pest insects, farmers continuously use insecticides, which eventually degrade into residue due to abiotic or biotic factors. These residual effects of pesticides may cause low lethal and/or sublethal impacts on the exposed pest insect populations, leading to the induction of pest resurgence through hormesis and ultimately the development of resistance. Hormesis is a beneficial bi-phasic effect generally characterized by low-dose reproductive stimulation and high-dose inhibition. In the present study, we investigated the impact of low lethal and sublethal concentrations (LC10, LC20, and LC30) of spinetoram, chlorantraniliprole, and thiodicarb on the F0 generation as well as their multigenerational hormesis effects on the F1 and F2 generations of Fall Armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). The study focused on reproductive parameters, fecundity, fertility, and life index parameters such as net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (λ), mean length of generation (Tc), and gross reproductive rate (GRR). Fecundity of S. frugiperda increased by 4.82%, 4.63% and 4.58%, while eggs fertility improved by 7.77%, 6.78% and 6.52% at LC10 of thiodicarb, chlorantraniliprole and spinetoram, respectively, from the F1 to F2 generation. Further, interaction analysis (Concentration × Insecticidal treatments) revealed that important vital parameters like pre-oviposition period (POP), oviposition period (OP), post-oviposition period (PtOP), R0,rm,λ, Tc and GRR of F0 were negatively impacted by LC30 of all the tested insecticides and LC20 of only spinetoram. However, LC10 of any of the tested insecticides did not affect these parameters when compared with control. Furthermore, interactive analysis in multigenerational exposure experiments (Concentration × Insecticidal treatments × Generation(s)) showed hermetic effects of LC10 of all tested insecticides which is more positive in F2 as compared to F1 generation. These unwanted positive hermetic effects of low lethal concentrations (LC10) of tested insecticides in offspring of exposed parental population of S. frugiperda indicated its resistance and/or resurgence. Furthernore, present study emphasizes the necessity for additional research to elucidate the underlying mechanisms responsible for these effects.

Biology, morphometrics and mating behaviour of reduviid predator, Rhynocoris marginatus (Fab.)

A biology study of Rhynocoris marginatus revealed that eggs of this species had a length of 2.65mm and breadth of 0.72mm, incubated for 8.07 days with an average 89% hatching rate. Average durations of first to fifth nymphal instars were 9.3, 9.5, 8.25, 11.4 and 19.45 days, respectively. The size of nymphs increased with successive nymphal instars with the first instar of 2.02 mm in length and the fifth instar being 9.4 mm in length. The average nymphal developmental period was 57.9±2.5 days. Female adults were easily distinguishable due to their broader size measuring a length of 15.2 mm and abdominal width of 5.92 mm, while male adults measured 12.3 mm in length and 4.2 mm in abdominal width. The sex ratio was female-biased (0.89:1). Pre-oviposition, oviposition and post-oviposition period lasted for 12.9, 44.6 and 5.6 days, respectively. Fecundity was 279±48.2 with an average of 45.5 eggs per batch. Female adults survived (63.1 days) more than males (42.1 days). Total generation time was found longer in females (129.3 days) than in males (108.8 days). Keywords: Reduviid bug, Morphometrics, Rhynocoris marginatus

Biology and Morphometry of Gram Pod Borer Helicoverpa armigera Hubner Infesting Gram Cicer arietinum L.

Aims: To investigate the biology and morphometry of gram pod borer Helicoverpa armigera Hubner infesting gram Cicer arietinum L.
 Place and Duration of Study: The investigation was conducted in the PG Research Laboratory, Department of Entomology, Navsari Agricultural University, Navsari, Gujarat, India under laboratory conditions at 26.7±1.66°C temperature and 51.11±6.35 per cent relative humidity during 2021-22.
 Methodology: The Helicoverpa armigera was reared from eggs to the adult stage under laboratory conditions. Twenty-five samples of eggs, larval instars, pre-pupa, pupa, and adults were used for morphometrics measurement and fifty samples of each stage were used for determining the biological parameters.
 Results: The Helicoverpa armigera female laid eggs singly or in batches of 2 to 3 during nighttime. The incubation period was 2.84±0.58 days with 58.39±4.22 per cent hatching. The larvae passed through six different instars having durations, 2.54±0.50, 4.04±0.88, 4.04±0.88, 4.24±0.77, 4.50±0.51, and 4.92±0.80 days of first, second, third, fourth, fifth, and sixth instars, respectively. The mean larval, pre-pupal, pupal, pre-oviposition, oviposition, and post-oviposition periods were 23.12±1.83, 1.64±0.69, 13.40±1.25, 2.60±0.49, 6.94±0.82, and 1.62±0.49 days, respectively. The lengths of egg, first, second, third, fourth, fifth, and sixth instar larvae, prepupa, pupa, and male and female adults, were 0.49±0.05, 1.56±0.12, 4.27±0.38, 8.47±0.70, 13.50±0.95, 21.84±0.97, 32.58±0.99, 25.03±0.97, 19.95±0.96, 17.25±0.56, and 20.32±0.95mm, respectively. Whereas, the breadths were 0.50±0.04, 0.46±0.03, 0.72±0.04, 2.45±0.03, 2.72±0.07, 3.22±0.11, 4.12±0.16, 3.88±0.39, 5.26±0.31, 34.44±1.09, and 39.86±1.03mm, respectively. The lengths of head capsules of first, second, third, fourth, fifth, and sixth instar larvae were 0.23±0.01, 0.45±0.01, 0.63±0.02, 1.12±0.01, 2.19±0.02, and 2.61±0.04, respectively which was not studied before. Whereas, the breadths were 0.26±0.01, 0.50±0.01, 0.73±0.01, 1.28±0.01, 2.22±0.01, and 2.70±0.05, respectively. The sex ratio of male to female was 1:0.76±0.05. The fecundity of gravid females was 544.85±63.89 eggs/female. The adult longevity was 9.04±0.78 and 10.54±0.99 days in males and females, respectively. The total life span was recorded as 47.20±2.57 and 48.70±2.79 days in males and females, respectively
 Conclusion: The Helicoverpa armigera adults completed their life cycle in 43 to 56 days. The adult longevity was higher in females than males. The males were smaller than the females. The sex ratio was male-biased. The various biological parameters would be useful in the planning of integrated management strategy under field conditions.

Temperature-dependent development and life tables of Palpita unionalis (Lepidoptera: Pyralidae)

Abstract Palpita unionalis Hubner (Lepidoptera: Pyralidae) is one of the primary pests in olive orchards, damaging buds and fruits of the olive tree. The present study investigated the biology of P. unionalis across a temperature gradient and elaborated on the corresponding life tables for a better understanding of its population dynamics in the environment. The biology of the pest was studied at six temperatures (17, 20, 22, 25, 27, and 30 °C). The duration and survival of immature stages, sex ratio, and survival of emerged adults were evaluated. The female fecundity and longevity (pre-oviposition, oviposition, and post-oviposition periods) were calculated. The life tables were elaborated from these parameters. The life cycle of P. unionalis was significantly longer at 17 °C and shorter at 30 °C. Larval survival was significantly reduced at 30 °C, however, adult survival was at a maximum, yet their sex ratio was not affected by temperature. The lower temperature, 20 °C, was optimal for fecundity (586.3 eggs), which was reflected in the highest net reproductive rate (105.7 offspring per individual). The thermal constant (K) and the lower thermal threshold (t 0) for egg to adult period were 582.9° days and 7.1 °C, respectively. Based on the current study, it is concluded from the parameters of biology and life tables that temperature has a significant role in the population growth of P. unionalis. This should be considered throughout the monitoring and management of P. unionalis at different agro-ecologies in the context of global warming.

Diet restriction in parents shapes the lives of their offspring: a laboratory study using a predatory mite (Acari: Phytoseiidae)

Environmental influences experienced by organisms are known to influence the phenotype of offspring through transgenerational plasticity or parental effects, and recent studies have revealed the significance of diet stress experienced by parents in shaping the life course of their progeny. In this laboratory study using a predatory mite, Phytoseiulus persimilis Athias-Henriot, we investigated the influence of parental diet restriction on offspring life history traits. We found that parental mites exposed to food reductions of 50% (Low diet) during both immature development and adult stages produced F1 offspring with reduced survival rates and fecundity compared to those from parents on abundant (High) diets. Sexually dimorphic responses emerged in response to parental diet restriction, whereby a reduced diet led to extended developmental periods for both male and female offspring while simultaneously reducing male size at maturity and increasing female size at maturity. We also found that diet restriction experienced by F0 individuals at both immature and adult stages manifested as reduced egg volumes and a less female-biased sex ratio in the F1’s offspring (i.e. the F2). There were additional significant interactions between the dietary history of parents and the dietary experiences of P. persimilis offspring themselves on various traits, including post-oviposition period, fecundity, and individual egg volume. These findings suggest that the dietary experiences of parents can modulate their offspring’s response when facing diet restriction. This study provided insights into non-genetic inheritance and transgenerational plasticity, highlighting the intricate interplay between environmental stressors and phenotypic responses.

Fitness consequences of feeding-by-remating interactions in female Cerambyx welensii (Coleoptera: Cerambycidae: Cerambycinae)

Abstract The longhorn beetle, Cerambyx welensii (Küster) (Coleoptera: Cerambycidae), is considered a critical factor in oak decline in southwestern Iberia, but populations vary over space and time, depending on several ecological factors. Adults feed on ripe fruits and tree exudates, and evidence suggests that feeding could impact fitness in hot, dry summers, especially under climate change. In the present study, we assessed the impact of adult feeding (sugar-fed, water-fed, or unfed) and remating (monandrous versus polyandrous) on female reproductive output. Lifetime fecundity increased with female size in most feeding–remating combinations. Sugar-fed females achieved the highest longevity and fecundity, unfed females the lowest, and water-fed females had intermediate values. The daily fecundity pattern was strongly dependent on female feeding. Longevity and fecundity of once-mated and remated females were similar in both unfed and water-fed groups; however, in sugar-fed females, remating enhanced fecundity and shortened life span. Preoviposition, oviposition, and postoviposition periods were distinctly affected by both diet and remating. Results show that females require sugar to maximise reproductive output and that a water supply may partially mitigate the fitness decline of unfed females. We conclude that female feeding must be considered to explain C. welensii spatio-temporal occupancy–abundance patterns in oak woodlands.

Biology of shoot and fruit borer, Earias vittella Fabricius (Noctuidae: Lepidoptera) on okra

The biology of fruit and shoot borer (Earias vittella F.) was studied under the natural conditions in the instructional farm of Uttar Banga Krishi Viswavidyalay in pre-kharif, kharif and post-kharif on okra. The study revealed that the egg incubation in pre-kharif, kharif and post-kharif revealed that the egg incubation were 3.18±0.40, 3.61±0.70 and 4.25±0.67 and larval period were 11.00±0.88, 11.00±0.82 and 13.01±1.81 during corresponding seasons respectively. The pupal period in pre-kharif, kharif and postkharif were 13.01±1.81; 11.00±0.82; 10.97±2.15 days respectively. The adult male longevities observed were 3.64±0.67, 5.60±0.70 and 7.33±0.97 during pre-kharif, kharif and post-kharif. On the other hand female longevities observed were about 7.45±1.57b; 8.87±1.10; 9.41±1.51 days in corresponding seasons respectively. The female fecundity during pre-kharif, kharif and post-kharif were 91.55±10.93, 117.55b±10.60 and 132.04±5.83 eggs in their lifetime. The pre-oviposition during pre-kharif, kharif and post-kharif were 1.64±0.50, 1.52±0.53 and 1.88±0.57 and the oviposition periods in corresponding seasons were 2.73±0.47, 3.22±0.79 and 4.32±0.52. While post-oviposition periods in pre-kharif, kharif and post-kharif were 3.09±0.70, 4.14±0.63 and 3.23±0.92 respectively. Its total life-cycle was completed in 27.45±1.57, 31.60±1.90 and 41.35±2.55 days during pre-kharif, kharif and post-kharif respectively. Higher fecundity may lead to faster population growth that may surpass the economic threshold level (ETL), even though the shoot and fruit borer’s life cycle is longer in Kharif and post-kharif. Thus, it may be said that the kharif and poskharif seasons are the most susceptible to shoot fruit and shoot borer infestation.

Studies on Reproductive Biology of Yellow Stem Borer, Scirpophaga incertulas Walker (Lepidoptera: Pyralidae) in the Changing Climate Scenario

Studies on reproductive biology of yellow stem borer, Scirpophaga incertulas walker in the changing climate scenario conducted at Agriculture Research Station, Gangavathi during 2020-22.Results on post eclosion behavior of yellow stem borer revealed that the maximum female moths emerged between 18:00 and 21:00 hrs from among the emerged moth the female calling was observed between 23:00 and 02:00 hrs. The time of mating commenced after the calling period and was observed between 23:00 and 03:00 hrs. The average pre-oviposition period, oviposition period and post-oviposition period were completed in 1.09 ± 0.09, 1.28 ± 0.17 and 0.85 ± 0.25 days, respectively. The longevity of adult females and males was about 3.23 ± 0.29 and 2.66 ± 0.33 days, respectively. The total number of eggs laid varied from 68 to 221 in number with an average of 146.95 ± 43.98 per female. The Operational and intrinsic sex ratio of YSB were observed to be female-biased with 1:1.35 and 1:1.44 of male to female moths, respectively.

A comparative study of biology and morphometrics of two different species of Earias on okra crop

Okra shoot and fruit borers, Earias insulana and Earias vittella are the major pests of economically important crops like okra and cotton. It is important to understand pest biology and ecology before initiating control measures, however little is known about their comparative biology on okra. Therefore, we studied biometrics of E. insulana and E. vittella in laboratory conditions on okra fruits and recorded the duration of different life stages along with their morphological parameters, to differentiate both the species. Oviposition was comparable in both species, however, incubation period and oviposition period was shorter in E. vittella. Although incubation, oviposition, post-oviposition period were at par in both the species, but there was a significant difference in larval and pupa periods. Total life cycle being comparable in both species, the larval period was significantly longer in case of E. insulana (13.8 days), while its pupal period (8.5 days) was significantly shorter in comparision to E. vittella (9.9 days). Sex ratio in E. insulana and E. vittella was recorded as 1:0.72 and 1: 0.61 (male: female) respectively. Both species were slightly different in terms of their morphological parameters. This study provides basic knowledge about the biology of these pests that may be helpful while formulating IPM strategies against them in okra as well as cotton.

Biology of Fruit Borer, Helicoverpa armigera (Hubner) on Tomato under Laboratory Conditions

The experiment on biology of fruit borer Helicoverpa armigera (Hubner) was carried out in the Bio-control Laboratory, Department of Entomology, S.V.P.U.A.&T., Meerut. Results showed that the mean pre-oviposition, oviposition and post-oviposition period of fruit borer on tomato lasted for 2.46 ± 0.29, 6.33 ± 0.14 and 1.67 ± 0.14 days, respectively. A female laid on an average 329.40 ± 68.17 eggs. The incubation period was observed to be 3.08 ± 0.32 days on tomato. The first instar larva was very active with body length of 1.54 ± 0.81 mm and body breadth of 0.46 ± 0.05 mm. The larval development completed within 22.45 ± 0.44 days. The duration of each instar on tomato was found to be 2.58 ± 0.26, 3.50 ± 0.14, 3.42 ± 0.26, 3.71 ± 0.28, 4.38 ± 0.16 and 4.83 ± 0.14 days, respectively. The mean pre-pupal period lasted for 2.00 ± 0.24 days on tomato. The mean pupal period lasted for 12.33 ± 0.62 days. Longevity of adult ranged from 8 to 11 days with an average of 9.30 ± 1.25 days in males, while the longevity of female moths ranged from 10 to 14 days with an average of 11.30 ± 1.34 days. The male moth measured 17.79 ± 0.41 mm in length, 35.55 ± 0.92 mm in breadth and the female moth measured 19.76 ± 0.58 mm in length, 40.08 ± 0.99 mm in breadth on tomato. The sex ratio for male and female was 1: 0.76 on tomato. The generation from egg to death of male and female i.e., total life cycle was found to be completed within 39 to 60 days with an average of 50.3 ± 7.51 days and 41 to 63 days with an average of 53.5 ± 7.93 days, respectively.

Development and life table parameters of the Phytoseius corniger Wainstein (Acari: Phytoseiidae) feeding on the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions

Phytoseiid mites are important for biological control of some pest species including phytophagous mites and small insects. The species, Phytoseius corniger Wainstein is one of the most abundant predatory mite in fruit orchards and urban green spaces in Razavi Khorasan province, Iran. Biological parameters of this predatory feeding on the two-spotted spider mite Tetranychus urticae Koch was studied for the first time under the laboratory conditions (25±2 ºC, 55±5 % RH and 16L: 8D photoperiod). The results indicated that the mean developmental periods for egg, larva, protonymph and deutonymph were 1.12±0.09, 0.73±0.03, 1.01±0.03, and 3.05±0.09 days for females, and 0.95±0.37, 0.67±0.39, 1.05±0.88, and 3.05±0.85 days for males, respectively. The pre-oviposition, oviposition, post-oviposition periods and adult longevity for females were 4.63±0.11, 11.63±0.16, 7.93±0.13 and 24.18±0.21 days, respectively. The females laid an average of 0.48 eggs per day, and 5.60 eggs during their life span. In addition, larvae of P. corniger may molt to the protonymph stage without feeding. Consumption rate during nymphal stage was 1.95 prey per day. The highest rate of prey consumption was recorded during the oviposition period, with an average of 3.35 prey items prey per day. Regarding life-history traits, the intrinsic rates of increase (rm) of this predatory mite 0.064±0.02 (♀♀/♀/day) and its finite rate of increase (λ), net reproduction rate (R0), generation time (T), and doubling time (DT) were 1.066±0.23 (day-1), 3±0.07 (♀♀/♀/generation), 17.14±0.11 (days), and 10.83±0.65 (days), respectively. Further laboratory and field studies regarding its diet preference and predation capacity are needed.

Mating Behaviour and Egg Laying Pattern of the Areca Nut White Grub, Leucopholis lepidophora (Coleoptera: Scarabaeidae)

The mating behaviour and egg laying pattern of the areca nut white grub, Leucopholis lepidophora, were studied in the Shivamogga district’s Hosanagara taluk. Females were active between 18:40 and 19:20 hrs, when light intensity dropped to 83.62 lux. The most males approached the virgin female at 18:50 hrs (15.94 lux) and the session ended at 19:20 hrs (0.26 lux). The typical mating behaviour of L. lepidophora was investigated. Female beetles began abdominal expansion and contraction, which could indicate that semiochemical secretion has begun. Males then approached, calling out to females. Male raised all of its legs, turned its body ventrally, and became suspended by the genitalia after inserting genitalia into the female abdomen. Copulation lasted an average of 74.60±6.61 minutes. The adult female’s pre-oviposition period, oviposition period, and postoviposition period were 9.56± 2.04 days, 3.72± 2.35 days, and 5.24± 4.67 days, respectively. Female longevity ranged from 11 to 28 days, with an average of 18.52± 4.91 days. The incubation period was 9.56± 2.04 days, with varying fecundity and clutch intervals ranging from 24-48 hours. Experiment on egg laying pattern revealed that females waited an average of 9.56± 2.04 days before oviposition began, after which they began to lay varying numbers of eggs at an average clutch interval of approximately 24-48 hours.

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.

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 <i>Earias Vitella</i> (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.

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.

Biology and Life Table of Fall Armyworm Spodoptera Frugiperda (J.E. Smith) on Maize at Laboratory Conditions in Nepal

The biology and life table of Spodoptera frugiperda (J.E. Smith) was studied at 27±2 °C temperature and 75±10% relative humidity at a Laboratory in the National Entomology Research Center, Lalitpur, Nepal from June to October, 2021.The main purpose of the study is to determine life cycle and to prepare stage specific life table of the insect on the preferred host maize. The mean incubation, larval and pupal periods were found to be 2.79, 14.04 and 9.49 days, respectively. The adult longevity of male and female moths was recorded at 15.39 days and 16.16 days. Pre-oviposition, oviposition and post-oviposition periods of female moths were 3.27 days, 5.39 days and 6.85 days with the fecundity of 1712 eggs per gravid female. The width of head capsules of the first, second, third, fourth and fifth larval instars was observed to be 0.31 mm, 0.51 mm, 0.81 mm, 1.30 mm and 1.95 mm, respectively. The highest apparent mortality (13.39) and indispensable mortality (10.02) were recorded in the insect’s egg stage. Among larval instars, the maximum apparent mortality (7.1) and indispensable mortality (4.72) were recorded in the first instar.

Fındık Yeşil Kokarcası [Palomena prasina L. (Hemiptera: Pentatomidae)]’nın Yumurta Paket Sayısı ve Üreme Kabiliyeti

This study was conducted to determine the fecundity, oviposition rhythm and clutch number variations of overwintering adult green shield bug (GSB) Palomena prasina (Hemiptera: Pentatomidae) in cages in hazelnut. The adults of GSB collected from hazelnut orchards were taken into cages on selected branches, one pair of overwintering adults were placed in each cage and the study was carried out with 20 repetitions. Daily observations were made during April-June (April 18-June 22) and it was found that the pest laid 94.88 eggs per female as a result of feeding on hazelnut fruits under field conditions. Oviposition period of females was found as 32 days on average. The average number of egg clutches laid per female is 4.38 and it was found that GSB laid eggs from the last week of April until the third week of June. The time required for each oviposition was varied and the average time was found as minimum 5 days and maximum 11.47 days. While postoviposition period was found as 12.25 days on average, death was found to occur on day 54.3 on average in overwintering females. It was found that most of the 79 clutches laid by the pest under cage conditions were included 28 and 14 eggs and there were an average of 21.62 eggs in the clutches laid by the bug. As a result, the determination of reproductive behaviours of the pest will also contribute to biological researches aiming to develop life tables, population models and biological control measures.

Predation stress experienced as immature mites extends their lifespan

The early-life experience is important in modulating the late-life performance of individuals. It has been predicted that there were trade-offs between early-life fitness and late-life success. Most of the studies on senescence have focused on the trade-offs between the reproduction and lifespan, and the influences of diet, mating, and other factors. Because the negative, non-consumptive effects of predators could also modulate the behaviour and underlying mechanisms of the prey, this study aimed to examine the different effects of predator-induced stress experienced in the early life compared with later life of the prey. The prey (Tyrophagus putrescentiae) was exposed to predation stress from the predator (Neoseiulus cucumeris) during different periods of its life (immature, oviposition period, and post-oviposition period). The results showed that the predation stress experienced during immature stages delayed development by 7.3% and prolonged lifespan by 9.7%, while predation stress experienced in the adult stage (both oviposition and post-oviposition periods) decreased lifespans of T. putrescentiae (by 24.8% and 28.7%, respectively). Predation stress experienced during immature stages also reduced female fecundity by 7.3%, whereas that experienced during the oviposition period reduced fecundity of the prey by 50.7%. This study demonstrated for the first time lifespan extension by exposure to predation stress when young and highlighted the importance of early-life experience to aging and lifespan.