Preoviposition Period Research Articles

Sublethal effects of a spiromesifen and abamectin combination on Tetranychus urticae (Acari: Tetranychidae) and its predators Phytoseiulus persimilis and Amblyseius swirskii (Acari: Phytoseiiidae).

The two-spotted spider mite, Tetranychus urticae Koch (TSSM), is an important cosmopolitan pest of agricultural crops that is often managed in greenhouses by augmentation of predatory mites in combination with acaricides. Here we examined the transgenerational effects of low lethal concentrations of a widely-used acaricide, Oberon Speed® (a combination of spiromesifen and abamectin), on the life history traits and population growth of T. urticae and two of its predators, Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). The concentrations employed corresponded to the LC10, LC20 and LC30 values estimated for TSSM protonymphs 48h post-exposure in a topical bioassay, which yielded an LC50 value of 207.2ppm. Parental exposure of TSSM to all three low concentrations increased the total developmental time of progeny; both the LC20 and LC30 treatments reduced adult longevity and number of oviposition days, but only the LC30 treatment increased the preoviposition period. Similarly, both the LC20 and LC30 treatments significantly reduced life table parameters (r, R0, λ, and GRR), and increased generation time (T) and population doubling time (DT). Although maternal exposure to the acaricide had various impacts on progeny life history, A. swirskii was less affected than P. persimilis, suggesting the former species would be more compatible for integration with Oberon Speed® for control of T. urticae in greenhouse vegetable production.

Oviposition biology and seed damage by Smicronyx lutulentus Dietz (Coleoptera: Curculionidae), a biological control agent of Parthenium hysterophorus L. (Asteraceae) in South Africa

The seed-feeding weevil Smicronyx lutulentus Dietz (Curculionidae) was released in South Africa in 2015 to supplement the biological control programme against the invasive annual weed Parthenium hysterophorus L. (Asteraceae). Larval feeding within young, developing ovules and larval-induced abortion of adjacent seeds within the flowerheads causes seed destruction, augmenting low levels of natural seed abortion. We studied female fecundity in a glasshouse trial, to identify critical periods in oviposition and inform mass-rearing and field release protocols. Newly emerged mated females displayed a pre-oviposition period of 1–2 weeks, a peak in oviposition after 7–8 weeks and a lifetime fecundity of 324–446 eggs. We also studied the relationship between weevil density and seed damage during two separate glasshouse trials, to facilitate predictions of seed damage under field conditions. Plants exposed to 15 mating pairs of weevils harboured substantially higher proportions of larval-damaged flower buds (75 %) than plants with five pairs (45–56 %) or a single pair (19 %). Larval progeny from five adult pairs caused significantly higher seed inviability (38 %) than progeny from a single pair (14 %), versus the weevil-free control (5 %). Progeny from 15 pairs damaged 30 % of developing seeds, potentially causing up to 60 % seed inviability due to enhanced abortion of neighbouring seeds. Although ≥5 females per plant caused appreciable seed damage, the proportions of unexploited new buds (25–55 %) versus buds with multiple occupancy (≥2 larvae; 35–47 %) indicate the importance of floral phenology in oviposition site selection, as flowerbuds of 2–3 mm are preferred. Although progeny from five females per plant could cause up to 30 % seed reduction, within a week of oviposition, higher densities are required to limit the entry of viable seeds into the soil seed banks.

Age-Stage, Two-Sex Life Table of an Alarming Quarantine Pest Trogoderma granarium on Stored Products

Trogoderma granarium (Coleoptera: Dermestidae) is a polyphagous pest of stored products and an alarming threat to food security around the globe. The current study is designed to construct the life table of T. granarium on four stored products, i.e., wheat, barley, rice, and maize at controlled conditions (33±1°C, 65% RH, and a photoperiod of 14 : 10 (L:D) h). The incubation period of T. granarium was longer (5.13 d) on maize and shorter (4.30 d) on wheat. The developmental period of 1st, 2nd, 3rd, and 4th larval instars of T. granarium was longer on maize than the other three hosts were significant. Statistical difference between the longevity of females and males was recorded, while no statistically significant difference was found in the preoviposition period. The mean fecundity values observed on wheat, barley, rice, and maize were 31.33±1.62, 26.21±1.49, 28.00±1.35, and 25.58±1.13, respectively. The highest fertility was observed in wheat and the lowest in maize. The net reproductive rate (R0) of T. granarium ranged from 8.66±2.86, 13.16±2.65, 12.53±2.27, and 10.23±2.32 offsprings on wheat, barley, rice, and maize, respectively. The highest gross reproductive value (GRR) was for T. granarium reared on barley (18.31±4.10/d), and the lowest was for maize (15.35±2.95/d). To complete the development, T. granarium took 48.97±0.68 d on maize, significantly higher than on other treatments (p<0.05). The mean generation time (T) of T. granarium was considerably affected by tested products. Based on the results of the present study, maize is a less favorable diet for the development and reproduction of T. granarium and may be considered for the management of this detrimental pest.

Influence of adult body size on blood feeding behavior and eggs retention in Aedes albopictus (Diptera: Culicidae).

Mosquito-borne viruses continue to affect billions of people globally, posing a severe health risk and an economic burden. Aedes albopictus (Skuse), a highly invasive mosquito species, has repeatedly invaded and increased its presence, serving as a key vector of dengue virus, yellow fever virus (YFV), Zika virus (ZIKV), and Chikungunya virus (CHIKV), causing frequent outbreaks of related viral diseases. This study investigated the impact of larval diet quantity on larval duration and adult body size. The effect of adult mosquito body size on various aspects of Ae. albopictus was also examined, including blood-feeding behavior, follicular development, reproductive capacity, egg retention capacity, preoviposition period, and fecundity. These diverse characteristics all have an effect on arboviruses transmission. The changes in body size (small, medium, and large) are obtained by providing different quantities of larval diet (low, average, and high). The results indicate that the quantity of larval diet directly impacts the adult body size while inversely affecting the larval duration. Furthermore, a positive correlation exists between adult body size and wing length, implying that wing length could be a reliable indicator of adult body size and rearing conditions during the developmental stages. Large females exhibited higher numbers of follicles and greater fecundity. Moreover, a significant correlation was observed between follicle number before the first blood meal and total egg number. In contrast, increasing wing length decreased the number of blood meals, egg retention, and the preoviposition period. The tendency of small females to perform multiple feedings was greater than that of large females. Small females exhibited a higher propensity for multiple feeding activities when compared to their larger counterparts. Most medium-sized females (92.8%) deposited eggs in their ovaries, however, 7.2% retained a few. In contrast, most large females (87.4%) had complete ovary egg-laying, whereas a minority (12.6%) retained some of their eggs. About 35.2% of small females showed ovarian egg retention, while 64.8% successfully laid all their eggs. After the first blood meal, the oviposition rate was 92% for large females, 88% for medium females, and 76% for small females. About 69.86% of the follicles in large females underwent vitellogenesis. This finding suggests that small females with low energy reserves exhibited incomplete oviposition and multiple blood feedings to increase their reproductive capacity. RESEARCH HIGHLIGHTS: Add more information about arbovirus epidemics and their consequences. Aedes albopictus is a global invasive species that transmit dengue virus, CHIKV, YFV, and ZIKV. A negative correlation was observed between body size, egg retention, and multiple blood feedings in Aedes albopictus. Size of the female's body was positively correlated with fecundity, while it was negatively correlated with the preoviposition period. Size-dependent multiple blood feeding affects vector-host contact frequency.

Effects of Prey Switching at Different Stages on Life Parameters of Neoseiulus bicaudus

The phenomenon of prey switching is prevalent in the natural world and represents a strategic adaptation of predators to their environment. Neoseiulus bicaudus, a native predatory mite found in Xinjiang, serves as a natural enemy to numerous small pests. The utilization of Tyrophagus putrescentiae as an alternative prey for the mass breeding of N. bicaudus is employed to fulfill the demands of enhanced breeding efficiency and cost-effectiveness. Following the introduction of mass breed N. bicaudus into the agricultural ecosystem, there was a switching in the prey of N. bicaudus from Ty. putrescentiae to Tetranychus turkestani. The objective of this study was to investigate the impact of prey switching at various stages on N. bicaudus. This study employed the age-stage, two-sex life table to assess the life parameters of N. bicaudus undergoing prey switching at different stages. The results showed that the survival rate of N. bicaudus was significantly decreased, the developmental period was significantly prolonged, the fecundity was improved during prey switching, and the intrinsic rate of increase of N. bicaudus was significantly decreased. The negative effects of prey switching in larva and deutonymph stages were greater than those in protonymph and adult stages. The stage and age of N. bicaudus undergoing prey switching were positively correlated with the male ratio, and negatively correlated with the total preoviposition period and the mean generation time. The comprehension of prey switching effects on N. bicaudus can enhance our understanding of the predator adaptation to environmental changes and contribute to the artificial rearing and application of natural enemy.

Biology and life table parameters of Paralobesia viteana (Lepidoptera: Tortricidae), grown on different grape cultivars.

The grape berry moth, Paralobesia viteana (Clemens), is an important pest of cultivated grapes in eastern North America. Damage is caused directly by larval feeding of grape clusters and indirectly by increasing fruit susceptibility to fungal and bacterial pathogens. Despite the impact of grape berry moth on grapes being widely recognized, there is a lack of understanding of the influence that different grape cultivars may have on grape berry moth development, reproduction, and population dynamics. In this study, we constructed age-stage 2-sex life tables for grape berry moth fed on 5 grape cultivars: Concord, Niagara, Riesling, Chambourcin, and Vidal, to examine the effects of diet on insect population development, survival, reproduction, and demographic parameters such as net reproductive rate, intrinsic rate of increase, finite rate of increase, and mean generation time. Our findings reveal that grape cultivar significantly influenced the neonate wandering period, larval developmental time, adult and female longevity, pupal weight, adult preoviposition period, oviposition period, mean generation time, age-stage-specific life expectancy, and reproductive value of P. viteana. However, diet type did not affect grape berry moth total fecundity or other demographic parameters. The highest female reproductive value was observed at 30-40 days of age, indicating that control tactics implemented during this time frame would have the greatest impact on reducing population increase. This study provides critical information on the effects of different grape cultivars on grape berry moth development, reproduction, and demography. These insights could lead to the development of management strategies that improve pest control and reduce economic losses in vineyards.

Investigation on the Biology of Helicoverpa armigera (Hubner) on Chickpea under Laboratory Condition

The Helicoverpa armigera (Hubner) is a polyphagous pest that is found throughout the world. Due to its damaging nature, it causes quantitative as well as qualitative loss and finally overalleconomic loss in agricultural crop production. So, the present investigation was done by rearing of H. armigera on chickpeas under laboratory conditions. The study revealed that this pest has four distinct stages i.e., egg, larva, pupa, and adult for completing its life cycle. The total life cycle of males and females were completed in 49-50 days and 52.30-53.00 days, respectively. The wholelife period was divided asthe incubation period takes 4-5 days, larval stage was completed in 20.00-20.50 days by passing through six instars under laboratory conditions at a temperature of 27±10C with 70±5 % relative humidity in 12 hours of light. The last larval instar did not molt and it contracted into a grub-like pre-pupal stage which lasted for 2-3 days and a pupal period of 13-14 days. The adult period of male and female insects was completed in 8.50-9.00 and 12.00-12.50 days, respectively. The female moths had a pre-oviposition period of 3-4 days that included a sexual maturity period. The oviposition and post-oviposition periodsrecorded were 5-6 days and 2 days, respectively. A single female produced on average 992.50-1085 eggs throughout her entire life span. The average hatching percentage of eggs recorded on 63.00-67.50 percent.

Comparison of the effect of tea shoots during different seasons in Arma chinensis (Hemiptera: Pentatomidae) reared on Ectropis grisescens (Lepidoptera: Geometridae) pupae.

In this study, we compared the growth, development, and fecundity of Arma chinensis (Fallou) reared on pupae of the geometrid Ectropis grisescens Warren fed on tea shoots during different seasons of the year. The raw data on life history were analyzed using the age-stage, 2-sex life table. When reared on spring or winter geometrid pupae, the duration of the immature stage of A. chinensis was significantly longer than in those produced during the summer or autumn. The survival rate of immature A. chinensis reared on autumn geometrid pupae was significantly lower compared to other treatments. Reproductive diapause was observed in adult A. chinensis reared on winter geometrid pupae. The adult preoviposition period (APOP), total preoviposition period (TPOP), and total longevity were significantly longer in A. chinensis reared on winter pupae than in the other treatments. The fecundity of A. chinensis reared on spring geometrid pupae was significantly lower than in the other treatments. The higher intrinsic rate of increase of the A. chinensis reared on summer pupae (r = 0.0966 day-1) and autumn pupae (r = 0.0983 day-1) resulted in higher fecundity, shorter immature duration, and shorter TPOP compared to the winter and spring populations. These findings can be utilized to enhance and sustain biological control of E. grisescens in tea plantations.

Diet and body size modulate the remating behaviour of a predaceous ladybird, Coccinella transversalis (Fabricius) (Coleoptera, Coccinellidae)

The nutritional condition and body size influence the mating and female remating behaviour of a predaceous ladybird, Coccinella transversalis. When well-fed males were provided with females of three different dietary conditions, viz. (i) well-fed, (ii) food-deprived and (iii) honey-fed, the well-fed ones were most fecund with highest percentage of egg-viability and least preoviposition period and remating refusals, while food-deprived ones showed vice-versa. However, honey-fed females laid unfertile eggs after coercively mating with males, and resisted the most to remate, which gets strengthened in the second mating trial. This indicates females’ nutritional condition modulates the females’ mating behaviour and post-mating outcomes. The adult body size was directly proportional to reproductive output with heavier females showing high fecundity and percentage of egg viability with least preoviposition period than the lighter ones. Large females resisted the least to remate with larger males than with smaller males, while large males coercively mated with smaller females. Regardless of body-size, the females’ remating resistance was enhanced in the second mating trial. Both diet and adult body size modulate the re-mating behaviour of female C. transversalis, as the food-deprived and large females greatly resisted to re-mate with smaller males.

Rice Stripe Virus Infection Facilitates the Reproductive Potential of Laodelphax striatellus

The rice stripe virus (RSV) is transmitted by the small brown planthopper Laodelphax striatellus in a persistent and circulative–propagative manner. During the last few decades, RSV has caused serious disease outbreaks in rice fields in China. The results of long-term coevolution have led to complex and diverse relationships between viruses and vector insects, and understanding these interactions is critical for the management of diseases and vector organisms. In this study, three groups of comparative experiments were performed to investigate the effects of RSV infection on the reproductive parameters, vitellogenin (Vg), and Vg receptor (VgR) expressions of L. striatellus. The results showed that RSV infection promoted the fecundity, hatchability, and Vg and VgR expressions of L. striatellus but had no effect on the preoviposition period and oviposition period. Furthermore, the RNA interference of the nucleocapsid protein (CP) gene and the injection of the CP antibody in RSV-viruliferous L. striatellus reduced the fecundity, hatchability, and Vg and VgR expressions, further strengthening the hypothesis that RSV may manipulate the reproductive behavior of insect vectors to promote its own transmission. The results of this study can further reveal the interaction mechanism of virus–vector insects in reproduction and virus transmission, and provide new insights for the control of insect-borne viruses.

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

Transgenerational effects of pyriproxyfen in a field strain of Musca domestica L. (Diptera: Muscidae).

Musca domestica L. (Muscidae: Diptera) is a human and livestock pest especially in tropical and sub-tropical areas. Different insecticides have been used to control this pest that pose serious harmful effects on humans and the environment. The current study was planned to investigate the effects of two concentrations (LC25 and LC50) of pyriproxyfen on biological and population parameters of a field strain of M. domestica. The exposed parents (F0) and their progeny (F1) were studied to examine the transgenerational effects. The results indicated that preadult duration was higher in control (13.68 days) compared to LC50 treated individuals (12.44 days). The male and female longevity was relatively lower in the LC25 treated population i.e. 24.62 and 26.62 days, respectively. The adult pre-oviposition period (APOP) and total pre-oviposition period (TPOP) values were higher in the LC25 treated individuals than those of control. Moreover, oviposition days and fecundity were reduced in the treated individuals as compared to the control treatment. A gradual decrease in the net reproductive rate (R0) was observed (8.46-14.07 per day) while the value of R0 was significantly higher in control. The results suggested that pyriproxyfen can be effectively utilized and incorporated in the management programs of M. domestica.

Biology of the non-parasitic phase of the cattle tick Rhipicephalus (Boophilus) microplus in an area of Amazon influence

BackgroundRhipicephalus (Boophilus) microplus is the most important tick species affecting cattle in the world. Under field conditions, the non-parasitic phase of R. (B.) microplus is unknown in the Amazon biome, including Brazil. The present study aimed to evaluate the non-parasitic phase of R. (B.) microplus in field (grass plots) and laboratory conditions.MethodsThe study was conducted from September 2020 to April 2022 in an Amazonian region (Maranhão State, Brazil). We evaluated the biological parameters of R. (B.) microplus under laboratory and field conditions. Engorged females were exposed to experimental conditions every 14 days, totaling 20 months of study. The following biological parameters were observed: pre-oviposition period, egg mass incubation period, and maximum larval survival period.ResultsAbiotic data (e.g., temperature and humidity) varied little throughout the year. Precipitation was the factor that varied the most throughout the year (dry ~ 30 mm3 and rain 400 mm3), and the parameters of pre-oviposition and pre-hatching are longer during the rainy season. A possible negative effect of the dry season on the percentage of hatched eggs was observed. Larval longevity in the plots of both control and free females was short (mean ~ 50–60 days), below that recorded for larvae under controlled conditions (mean ~ 95 days).ConclusionsRhipicephalus (Boophilus) microplus was able to complete its non-parasitic phase by producing host-seeking larvae in the pasture during all months of the study. The results indicate that R. (B.) microplus can complete up to six generations per year in biome Amazon. To our knowledge, this is the highest number of annual generations for R. (B.) microplus in Latin America.Graphical

Alpha- and beta-pinene isomers act differently to control Rhipicephalus microplus (Acari: Ixodidae).

The cattle tick Rhipicephalus microplus is an ectoparasite of high importance in veterinary medicine and public health. Since synthetic chemicals used to control these ticks can select resistant strains and cause toxic effects in their hosts, there is a need to identify effective substances with fewer adverse effects. For this reason, we investigated the effects of alpha- and beta-pinene, known for their various biological effects, on the mortality and reproductive performance of R. microplus engorged female ticks. The products were diluted in a 2% Tween 80 aqueous solution. The ticks were first weighed and then immersed in the test solutions for five minutes. Then, they were dried with paper towels and fixed dorsoventrally in Petri dishes, totalling five treatment groups for each pinene and a control group treated with the solvent alone. The ticks were monitored daily for mortality, and their eggs were collected and weighed. The larval hatching rate was estimated, and the pre-oviposition and incubation periods were determined. From these data, the following parameters were calculated: egg production index, fertility rate, estimated reproduction rate, percentages of reduction in oviposition and hatching, and product efficacy. Alpha-pinene showed better results at higher concentrations, unlike beta-pinene, which was more effective at lower concentrations. The effectiveness of alpha-pinene was 74% at a concentration of 14.0 μL/mL, while beta-pinene showed 78% efficacy at 2.0 μL/mL. The results indicated for the first time different effects of two isomers in ticks, suggesting that these compounds act on R. microplus females in different ways.

Effect of X-ray irradiation on the biological parameters of Xestia c-nigrum.

The sterile insect technique (SIT) is widely used to control Lepidopteran pests by inducing inherited sterility. The noctuid moth Xestia c-nigrum is a polyphagous pest whose subterranean larvae severely injure cereals and some vegetables. The goals of this study were to assess the impact of X-ray irradiation on the development and survival of X. c-nigrum and use the data to select suitable sterilizing doses for potential future use in pest management. Batches of male pupae were exposed to 0 (control), 10, 30, 50, 100, 200, 300, or 400Gy of X-rays, approximately 24h before adult emergence. Exposure of late-stage pupae to 10-200Gy of radiation had no significant effect on adult emergence, but all doses (10-400Gy) reduced adult longevity, the number of spermatophores in mated females, and the number of eggs laid per female in the irradiated parental generation compared with the controls. Exposure to 10 and 30Gy had no significant effects in the F1 generation on 1) the rate of egg hatch, 2) the duration of larval or pupal development, or 3) adult longevity. However, exposure to 50Gy reduced the rate of egg hatch in the F1 generation, and when male pupae were exposed to 100Gy only 1% of the F1 eggs hatched. Also at 100Gy, the developmental durations of larvae and pupae were significantly prolonged, and longevity of adult moths was reduced. There were no significant differences between the control group and any treatments in 1) the sex ratio of the F1 adults, 2) the duration of F1 pre-oviposition or oviposition periods, or 3) the number of eggs laid per F1 female. Our findings indicate that a dose of 100Gy can effectively slow pest development and reduce larval survival in the F1 generation. In addition, F1 adults from lines treated with 100Gy were able to mate and lay eggs, but all F2 eggs failed to hatch. Our results suggest that use of X-ray irradiation has potential to control this polyphagous pest at the regional level.

Characterization of Spodoptera littoralis (Lepidoptera: Noctuidae) resistance to indoxacarb: inheritance mode, realized heritability, and fitness costs.

Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae) is a major economic pest attacking a variety of crops in Egypt and other Mediterranean countries. S. littoralis has developed resistance to both traditional and novel insecticides. The current study investigated S. littoralis resistance to indoxacarb regarding inheritance mode, realized heritability (h2), and fitness costs. An indoxacarb-resistant strain (Indoxa-SEL) was obtained by selecting a field strain with indoxacarb. Indoxa-SEL strain outperformed the susceptible one (Indoxa-S) by 29.77-fold after 16 consecutive generations of selection. Based on the LC50 values of the progenies of reciprocal crosses F1 (R♂ × S♀) and F1' (R♀ × S♂), S. littoralis resistance to indoxacarb was found to be autosomal and partially recessive. Chi-square tests for goodness-of-fit between observed and expected mortalities of self-bred F1 and resistant strain reciprocal crosses revealed that the resistance was controlled by multiple genes. The resistant strain had a relative fitness of 0.80, with significantly increased total preovipositional period of females, egg, larvae, pupae, preadult, adult, and total longevity period. The estimated realized heritability value in the Indoxa-SEL strain was 0.21. The current study will contribute to sustaining indoxacarb efficacy and designing effective resistance management programs against S. littoralis.

Transcriptomics Provide Insights into the Photoperiodic Regulation of Reproductive Diapause in the Green Lacewing, Chrysoperla nipponensis (Okamoto) (Neuroptera: Chrysopidae).

Chrysoperla nipponensis (Okamoto) displays typical adult reproductive diapause under short photoperiods; however, our understanding of the molecular mechanism underlying photoperiod-sensitive reproduction remains limited. In this study, we performed transcriptome profiling of four treatments (the diapause-sensitive stage and pre-diapause phase under long and short photoperiods) of C. nipponensis using RNA sequencing (RNA-seq). A total of 71,654 unigenes were obtained from the samples. Enrichment analysis showed that fatty acid metabolism-related pathways were altered under a short photoperiod. Moreover, β-oxidation-related gene expression was active during the diapause-sensitive period under a short photoperiod. The knockdown of juvenile hormone acid methyltransferase 1 (Jhamt1) prolonged the pre-oviposition period but did not affect the reproductive ability of female individuals in C. nipponensis. These findings provided us with a more comprehensive understanding of the molecular mechanisms of photoperiod-sensitive diapause and show that groundwork is crucial for bolstering the long-term storage and biocontrol potential of C. nipponensis.

Demographic Parameters of Anthocoris minki Dohrn (Hemiptera: Anthocoridae) Reared on Common Bean (Phaseolus vulgaris L.), Faba Bean (Vicia faba L.) and Pea (Pisum sativum L.) as Egg Laying Media.

Anthocoris minki Dohrn (Hemiptera: Anthocoridae) is used as a biological control agent of various agricultural pests. This study determined the effect of different egg laying materials, i.e., faba bean, common bean, and pea on population parameters of A. minki using age-stage, two-sex life table. The longest (34.45 d) and the shortest (21.32 d) adult longevity was noted on common bean and pea, respectively. Likewise, the highest (92%) and the lowest (69%) preadult survival rate was recorded on faba bean and pea, respectively. The highest fecundity (93.74 eggs/female) was noted on faba bean followed by common bean (43.95 eggs/female) and pea (48.69 eggs/female). Oviposition period remained unaffected, while higher oviposition days (22 d) were noted on faba bean compared with common bean (10 d) and pea (14 d). The shortest and the longest adult pre-oviposition period and total pre-ovipositional period were calculated for common bean and pea, respectively. The highest intrinsic rate of increase (r) (0.1159 d-1) and finite rate of increase (λ) (1.1229 d-1) were noted on common bean, while the lowest (r = 0.0939 d-1; λ = 1.0985 d-1) were noted on pea. Paired bootstrap analyses indicated that the highest net reproductive rate (R0) (43.12 offspring) was recorded on faba bean. Egg hatching rate significantly differed among plants (P < 0.01) and it was 80.50%, 71.10%, and 38.90% on common bean, faba bean and pea, respectively. It is concluded that faba bean would be the most suitable host for mass rearing of A. minki, while pea proved unsuitable.

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.&#x0D; 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.&#x0D; 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.&#x0D; 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&#x0D; 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.