Highest Net Reproductive Rate Research Articles

Seasonal population fluctuation and life history in different temperatures of Myzus cerasi (Hemiptera: Aphididae) on cherry trees: a field and laboratory study.

This study determined the seasonal population fluctuation of Myzus cerasi (Fabricius) (Hemiptera: Aphididae) in cherry orchards and the effect of different temperatures on the life-history parameters of these aphids under laboratory conditions. Our field results showed that the population fluctuations and densities of M. cerasi on cherry trees were positively affected by the temperature increase between seasons. Also, our laboratory results showed that M. cerasi survived and reproduced at all temperatures tested under laboratory conditions. Female longevity was observed as 19.00 ± 2.38, 18.72 ± 0.49, and 12.59 ± 0.74 days, and fecundity was 10.14 ± 2.26, 9.36 ± 0.59, and 7.27 ± 0.84 offspring/female at 20, 25, and 30 °C, respectively. Although the highest net reproductive rate (R0) was observed numerically at 25 °C (7.80 offspring/female), there was no significant difference compared to 20 °C (7.10 offspring/female). The highest intrinsic rate of increase (r) and the highest finite rate of increase (λ) were calculated at 30 °C (0.15 ± 0.01 and 1.16 ± 0.01 day-1, respectively), and there was no significant difference compared to 25 °C. The mean generation time (T) of M. cerasi showed a significant difference at all temperatures tested and decreased from 22.59 ± 0.33 days at 20 °C to 12.78 ± 0.37 days at 30 °C. Consequently, our results revealed that the seasonal population fluctuation and the life history of M. cerasi in the field and laboratory conditions were affected significantly by different temperatures. Our data obtained in the field and the laboratory will contribute to the understanding of M. cerasi biology and to the management of the pest.

Temperature-induced effects on development, reproduction, and predation of Harmonia axyridis fed on first instar larvae Spodoptera litura.

Since metabolism, survival, and reproduction in hexapods are closely related to temperatures; changes in the mean and variance of temperature are major aspects of global climate change. In the typical context of biological control, understanding how predator-prey systems are impacted under thermal conditions can make pest control more effective and resilient. With this view, this study investigated temperature-mediated development and predation parameters of the predator Harmonia axyridis against the potential prey Spodoptera litura. The age-stage, two-sex life table of the predator was constructed at four temperatures (i.e. 15, 20, 25, and 30°C) by feeding on the first instar larvae of S. litura. Our results showed that the mean generation time (T) decreased but the intrinsic rate of increase (r) and the finite rate of increase (λ) increased with increased temperature. The mean duration of the total preadult stage decreased with higher temperatures. The T and r were 70.47 d and 0.0769 d-1 at 15°C; 58.41 d and 0.0958 d-1 at 20°C; 38.71 d and 0.1526 d-1 at 25°C; and 29.59 d and 0.1822 d-1 at 30°C, respectively. The highest net reproductive rate (R0) and fecundity were obtained at 25°C. The highest λ (1.1998 d-1) and lowest T (29.59 d) were obtained at 30°C, whereas the maximum net predation rate (C0) was at 25°C. Total population and predation rates projections were the highest at 30°C. Based on these findings, we anticipate that biological control strategies for this predator release against S. litura should be attuned to warming scenarios to achieve better biocontrol functions.

Life-history traits of Aedes aegypti (Linnaeus) distributed across a latitudinal range of 23 °N-6 °S.

The growth and associated traits of Aedes aegypti (L.) mosquitoes may adapt and evolve in response to the costs associated with body size in relation to latitudinal variation. We analyzed the life-history traits and energy reserves of field-collected mosquitoes from Taiwan, Thailand, and Indonesia along a latitudinal range spanning from 23°N to 6°S. A U-shaped relationship between body size and latitude was observed. Our study demonstrated the role of latitudinal temperature variations in determining the body size patterns of Ae. aegypti. Notably, the body size of the northern populations (from Taiwan) was significantly larger than those of the tropical populations from Thailand and Indonesia. Models have demonstrated that regional precipitation levels may contribute to body trait variations in certain high-latitude populations in Thailand. However, Indonesian populations have high development rates and large body sizes, indicating the involvement of other physiological traits in determining mosquito body size. The reproductive output of the adult females in this study was positively correlated with body size, but our measure of longevity did not covary significantly with the body size. By contrast, the reproductive output of mosquito-tested populations was in inverse proportion to longevity. Additionally, the mean teneral glycogen levels in the Indonesian and Thai populations were 2.5 times higher than those in the Taiwanese populations. The Indonesian and Thai populations had low mean generation and doubling times, resulting in a high intrinsic rate of increase compared with that of the Taiwanese populations, despite the Taiwanese populations having the highest net reproduction rate.

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.

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.

The application of demographic characteristics of Ectropis grisescens (Lepidoptera: Geometridae) in pest risk assessment of IPM.

Ectropis grisescens Warren is one of the most important pests of tea plants. In this study, data on the development, survival, and fecundity of E. grisescens were collected at 15, 22, and 32 °C and analyzed by using the age-stage, two-sex life table. At 15 °C, the duration of the preadult period of E. grisescens was significantly prolonged (81.06 days), with high mortality (69.0%), and the proportion of emerged female adults was extremely low (7.0%). At 32 °C, the preadult period was significantly shortened (29.12 days), with high preadult mortality (74.0%), and a low proportion of emerged female adults (15.0%). At 22 °C, with low preadult mortality (24.0%), and a high proportion of emerged female adults (26.0%). The overall effects of the shorter preadult duration, higher preadult survival rate, higher proportion of emerged female adults, higher fecundity (F = 350.88 eggs/♀), and higher net reproductive rate (R0 = 91.23 offspring/individual) at 22 °C resulted in the highest values of the intrinsic rate of increase (r = 0.1054 days-1) and finite rate of increase (λ = 1.1112 days-1). Computer simulation showed that E. grisescens populations can increase much faster at 22 °C than at 15 and 32 °C. The weighted population size and cumulative weighted insect-days provided the dynamics necessary for estimating the damage potential of E. grisescens in devising economical pest management programs. Our results demonstrate that populations of E. grisescens were able to develop at a broad range of temperatures and adapt to the high temperatures. These finding can be utilized to improve the management of E. grisescens.

Effect of temperature on the life history and development of Typhlodromus athiasae Porath and Swirski (Acari: Phytoseiidae) as a predator of Tetranychus urticae Koch (Acari: Tetranychidae)

The present study determined the effects of different temperatures on the life history parameters and development of Typhlodromus athiasae Porath and Swirski (Acari: Phytoseiidae) for the first time. The study was conducted at 20, 25 and 30°C and the predators fed on Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions. Our results show that temperature significantly affected pre-adult and adult durations of T. athiasae. The adult longevity was calculated as 47.90, 22.88, 19.50 days for females, 26.11, 19.90, 20.46 days for males at 20, 25 and 30°C, respectively. The adult females of T. athiasae laid 15.80 (eggs/female), 17.20 (eggs/female) and 12.38 (eggs/female) eggs at the respective temperatures tested. The highest net reproductive rate (R0= 8.90 offspring/individual) determined at 25°C but no significant difference was found among the other temperatures. The highest intrinsic rate of increase (r= 0.12 day-1) was observed at 25°C and 30°C. Although the highest finite rate of increase (λ= 1.13 day-1) was determined at 25°C, no significant difference was observed between this temperature and 30°C. Also, the shortest mean generation time (T=14.97 day) was obtained at 30°C whereas the longest mean generation time (T=28.39 day) was observed at 20°C. Our results revealed that 25°C was more suitable for mass production even if the female and male of T. athiasae survived and reproduced at all temperatures. Consequently, our present results and the data to be obtained in greenhouse and field conditions will reveal the potential of T. athiasae as a biological control agent of T. urticae.

Life history of Neoseiulus agrestis (Karg) (Acari: Phytoseiidae) fed on the storage mite, Thyreophagus sp. (Acari: Acaridae) at different temperatures

The development and life history parameters of Neoseiulus agrestis feeding on the storage mite, Thyreophagus sp., were studied at three different temperatures of 20, 25, and 30 °C. The results show that juvenile development and oviposition period as well as reproductive potential of this predatory mite are significantly affected by the temperature. The development times of immature and the life expectancy of adults ranged from 11.36 to 6.06 days and 58.71 to 38.65 days, respectively, depending on the temperature. The average total number of eggs laid per female at 20 °C (27.21), 25 °C (46.38), and 30 °C (61.12) differed significantly from each other. The highest net reproductive rate (R&lt;sub&gt;0&lt;/sub&gt;) was 51.95 (offspring/individual) at 30 °C, although there was no significant difference from that obtained at 25 °C (37.10). Furthermore, the highest intrinsic rate of increase (r&lt;sub&gt;m&lt;/sub&gt;) is 0.286 day&lt;sup&gt;-1&lt;/sup&gt; at 30 °C. Moreover, the highest finite rate of increase (λ = 1.331 day&lt;sup&gt;-1&lt;/sup&gt;) and the shortest mean generation time (T = 13.786 days) and doubling time (DT = 2.418 days) were also determined at 30 °C. Our results indicate that N. agrestis successfully completed immature development and can survive and reproduce at all temperatures tested. However, a number of biological traits of this predator are affected by the temperature on this food source. Finally, a temperature of 30 °C seems to be more suitable for mass rearing of this predator on Thyreophagus sp. Further studies should be carried out to determine the biological characteristics and life cycle parameters of N. agrestis on various important pests such as spider mites, whiteflies and thrips.

Age-stage, two-sex life table analysis of black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), reared on different organic wastes

Hermetia illucens or black soldier fly (BSF) is an economically important species. BSF larvae are efficient decomposers of various organic wastes and can be integrated into animal feed formulations. An age‐stage, two‐sex life table was applied in this study to evaluate the influence of four different organic wastes, namely, food waste, coconut endosperm, palm kernel expeller (PKE), and chicken manure. The development period, survival, fecundity of BSF adult longevity, adult pre‐oviposition period (APOP), and total pre‐oviposition period (TPOP) were observed to estimate the performance of BSF on different organic wastes. This study was conducted under laboratory conditions at 28 ± 2 °C and 70 ± 10 % relative humidity with a 15-hour light:9-hour dark photoperiod. Raw BSF data were analyzed using the TWOSEX MS‐Chart computer program. Life table parameters showed that food waste and PKE treatments were superior diet choices for BSF larvae compared to chicken manure and coconut waste treatments, with PKE treatment showing the ideal result out of all treatments. The highest net reproductive rate (R0 = 78.5567 ± 14.33) and highest fecundity (467.57 ± 27.28) of BSF occurred in the PKE treatment. Treatment significantly affected the fecundity, intrinsic rate of increase (r), and finite rate of increase (λ).

Temperature-Dependent Biology and Population Performances of the Coffee Berry Borer Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae) on Artificial Diet

At different observation intervals of 1, 5, and 10 days during a trial period of 30 days, the mortality rates of Hypothenemus hampei were 100, 95, and 55%, and the fecundity rates were 0.55, 8.45, and 19.35 eggs/female, respectively. At temperatures of 18, 21, 24, and 27 °C, the development time of the immature stage of H. hampei was significantly shortened with increasing temperature. Furthermore, the lower developmental threshold (T0) and thermal summation (K) of the immature stage were 8.91 °C and 485.44 degree-days, respectively. The greatest longevity of female and male adults reached 115.77 and 26.50 days, respectively, at 18 °C. The highest fecundity was 29.00 eggs/female at 24 °C. The population parameters of H. hampei were analyzed on the basis of the age–stage, two-sex life table theory. According to the data, the parameters were significantly affected by temperature. The highest net reproductive rate (R0) was 13.32 eggs/individual at 24 °C. The highest intrinsic rate of increase (r) and finite rate of increase (λ) were calculated as 0.0401 and 1.0409 day−1, respectively, at a temperature of 27 °C. The shortest mean generation time (T) was 51.34 days at 27 °C. Overall, we provide a discussion on comprehensive biological information regarding H. hampei, thus providing basic knowledge for further research on this pest.

Population Growth Parameters of Helicoverpa armigera (Hübner) on Various Legume Seeds Reveal Potential Tolerance Traits

Helicoverpa armigera (Hübner) is a key polyphagous pest with global spread that causes economic damage to agricultural crops. It is commonly managed by synthetic insecticides, which can cause negative impacts on the environment and human health, as well as toxicity to natural enemies. Hence, investigations into alternative pest management approaches such as the use of resistant host plant cultivars against H. armigera is important. In this study, the effects of various legume seeds based on meridic diets were evaluated using biology and population growth parameters of H. armigera under laboratory conditions. The results indicated that the shortest developmental time and pupal incubation periods occurred on white kidney bean Dehghan, while the longest periods occurred on broad bean Mahta. The intrinsic rate of population increase (r) was highest when H. armigera was reared on white kidney bean Dehghan and cowpea Arabi, and the lowest when reared on broad bean Mahta and common bean Khomein. Furthermore, the highest net reproductive rate (R0) occurred on white kidney bean Dehghan and the lowest on common bean Khomein. Cluster analysis revealed that white kidney bean Dehghan and cowpea Arabi were the most susceptible hosts, while common bean Khomein, and broad beans Feyz and Mahta were the poorest and perhaps least susceptible hosts for population growth of H. armigera. Our results suggest that the selective use of certain bean cultivars as potential sources of antibiosis against this pest may be useful as part of an integrated management program.

Evolution Under Dietary Restriction Increases Reproduction at the Cost of Decreased Somatic Growth.

Dietary restriction (DR) is cited as the most reliable means of extending life span in a wide range of taxa, yet the evolutionary basis of the DR effect on life span remains unclear. The resource reallocation hypothesis proposes that the longevity-extending response of DR is adaptive and stems from the reallocation of resources from reproduction to somatic maintenance under food-limited conditions. However, if DR continues for multiple generations, such a response becomes maladaptive, and genotypes with higher fecundity should be selectively favored over genotypes with longer longevity. To test this prediction, we exposed replicate populations of the rotifer Brachionus dorcas, a model organism for aging and experimental evolution studies, to DR and ad-libitum (AL) diets for 100 days. During the selection experiment, AL-selected populations showed higher growth rates and mictic ratios than DR-selected populations. After approximately 27 asexual generations of selection, populations with a DR selection history had a higher net reproductive rate but lower body volume and ingestion rate in the absence of survival costs than populations with an AL selection history when they were assayed on an AL diet. Our results are inconsistent with the prediction that evolution on sustained DR increases reproduction and reduces life span, and show for the first time that sustained DR selects for clones with higher energy investment in reproduction but lower investment in somatic growth.

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.

Neraca Kehidupan Spodoptera pectinicornis (Hampson) dengan Pakan Gulma Kayu Apu Pistia stratiotes Linn yang diberi Pupuk NPK dan AB Mix

This study aims to examine the life balance of the biological control agent Spodoptera pectinicornis fed Pistia stratiotes with NPK and AB mix fertilization.. The research was carried out from March to May 2021 at the Laboratory Pengendalian Hayati and Greenhouse Entomology Faculty of Agriculture University Lambung Mangkurat Banjarbaru. The data in this study were analyzed descriptively by calculating the population. S. pectinicornis in one life cycle. There are 3 treatments and 3 replications on the 100 egg s. pectinicornis, The highest gross reproductive rate (GRR) was in the AB mix treatment of 1912 individuals/generation. The highest net reproduction rate (Ro) was found in the AB mix treatment of 129.520. The average value of the shortest generation period (T) in the NPK fertilizer treatment was only 26.334 days. The highest intrinsic growth rate (r) was found in the AB mix fertilizer treatment of 0.164 individuals/parent/day. The calculation of the limited growth rate (λ) showed that the AB mix treatment had the highest population increase of 1,174 individuals/parent/day. Apu wood treated with NPK and AB mix fertilizers can increase the rate of population development in the life table of the insect S. pectinicornis.

Effects of temperature on life table parameters of a newly described phytoseiid predator, Neoseiulus neoagrestis (Acari: Phytoseiidae) fed on Tyrophagus putrescentiae (Acari: Acaridae)

The predatory mite, Neoseiulus neoagrestis Khaustov and Döker (Acari: Phytoseiidae), recently described as new species for science, but seems to have a great potential to be used in biological control. In this study, as a first step to determine the optimum temperature (between three temperatures tested) for its mass rearing, we studied its biological characteristics and life table parameters fed on Tyrophagus putrescentiae (Schrank) (Acari: Acaridae) at three different temperatures (20, 25, and 30 °C) under laboratory conditions. Results show that immature development, oviposition period as well as reproductive potential of this predator are significantly vary depending on the temperature. The immature developmental times and adult longevity for females, are ranged between 5.42 to 10.42 days and 39.88 to 74.12 days, based on the temperature, respectively. Average total number of eggs laid by per female at 25 °C (62.29) and 30 °C (58.65) are more or less similar but higher than that determined at 20 °C (41.46). The highest net reproductive rate (R&lt;sub&gt;0&lt;/sub&gt;) is 29.066 (offspring/individual) at 25 °C. In addition, the highest intrinsic rate of natural increase (r) is 0.241 day&lt;sup&gt;-1&lt;/sup&gt; at 30 °C. Furthermore, the highest finite rate of increase (λ = 1.272 day&lt;sup&gt;-1&lt;/sup&gt;), and the shortest mean generation time (T = 13.416 days) and doubling time (DT = 2.874 days) are also determined at 30 °C. Our results demonstrate that N. neoagrestis successfully completed immature development, and can survive and reproduce at all tested temperatures. Nevertheless, a series of biological characteristics of this predator are differentially affected by the temperature. Finally, 25 °C and 30 °C seems to be more suitable for mass rearing of this predator on T . putrescentiae. Further studies should be conducted to determine biological characteristics and life table parameters of N. neoagrestis on several important pests such as spider mites, whiteflies and thrips.

Evaluation of Hemp (Cannabis sativa) (Rosales: Cannabaceae) as an Alternative Host Plant for Polyphagous Noctuid Pests.

Hemp (Cannabis sativa L.) is a reemerging crop in the United States with increasing outdoor acreage in many states. This crop offers a potential host for polyphagous, defoliating lepidopteran pests currently present in Louisiana. The ability of soybean looper [Chrysodeixis includens (Walker)] (Lepidoptera: Noctuidae), fall armyworm [Spodoptera frugiperda (J.E. Smith)] (Lepidoptera: Noctuidae), and beet armyworm [Spodoptera exigua (Hübner)] to develop and reproduce on hemp was investigated in this study. Insects were reared on two hemp varieties, Maverick and Pipeline, as well as documented host plants soybean [Glycine max (L.) Merr.] (Fabales: Fabaceae) variety UA5414RR and cowpea [Vigna unguiculata (L.)] (Fabales: Fabaceae) variety Quickpick Pinkeye. Larvae of all three species reared on 'Maverick' had significantly faster preadult developmental times compared to the other hosts. Chrysodeixis includens larvae fed excised leaves of 'Maverick' and 'Pipeline' experienced higher intrinsic and finite rates of increase, higher net reproductive rates, and faster mean generation and doubling times. Spodoptera frugiperda larvae reared on 'Maverick', 'Pipeline', and 'UA5414RR' had higher intrinsic and finite rates of increase, higher net reproductive rates, and faster mean generation and doubling times compared to 'Quickpick Pinkeye'. Spodoptera exigua larvae had the highest survivorship on 'Maverick' and similar, positive lifetable statistics when reared on 'Maverick' and 'Pipeline'. The results of this study indicate hemp is an alternative host plant that has the potential to influence the population dynamics of C. includens, S. frugiperda, and S. exigua in Louisiana agroecosystems they co-occur in.

Life Table Parameters and Digestive Enzyme Activity of Spodoptera littoralis (Boisd) (Lepidoptera: Noctuidae) on Selected Legume Cultivars.

Simple SummarySpodoptera littoralis (Boisd) is a highly polyphagous and destructive pest, which attacks a wide range of economically important crops throughout the world. The extensive use of conventional insecticides for management of S. littoralis has resulted in development of resistance to major classes of pesticides and can have a negative impact on the environment. It is necessary to investigate alternative pest management approaches that are more cost-effective and sustainable than conventional insecticides. The aim of this study was to identify potential sources of variation in resistance/susceptibility of legume cultivars to S. littoralis, and to describe potential interactions between cultivar traits and digestive function of this pest. We conducted life table analyses and assessed both proteolytic and amylolytic activities of S. littoralis on 11 common legume cultivars. The findings indicated that S. littoralis reared on the common bean, Arabi, displayed the highest intrinsic rate of increase, while the lowest was recorded on the cowpea, Mashhad. Developmental time of S. littoralis larvae was negatively correlated with protein content, while amylolytic activity was positively correlated with starch content of legumes. Our results revealed that the Mashhad cultivar exhibited tolerance traits against S. littoralis, which may prove useful for integrated programs that aim to reduce chemical inputs.Spodoptera littoralis (Boisd) is a highly destructive pest that attacks a large number of economically important crops. We examined life table parameters as well as activity of major digestive enzymes of S. littoralis larvae in response to protein and starch contents across 11 legume cultivars to identify potential resistance traits. The results showed that S. littoralis reared on the common bean, Arabi, displayed the highest intrinsic rate of increase (r), while the lowest was recorded on the cowpea, Mashhad. Also, the highest net reproductive rate (R0) was obtained in those insects reared on the Arabi cultivar. Larvae displayed the highest and lowest proteolytic activities when fed on Mashhad and Arabi cultivars, respectively. The highest amylolytic activity was quantified in larvae that fed on the Arabi and 1057 cultivars, while the lowest occurred in larvae feeding on Yaghout and Mashhad cultivars. Developmental time of S. littoralis larvae was negatively correlated with protein content, while amylolytic activity was positively correlated with starch content of legumes. Our findings indicate that Arabi was a susceptible cultivar, while Mashhad exhibited tolerance traits against S. littoralis. These results should facilitate selection of legume cultivars for production or breeding efforts that involve S. littoralis management.

Effects of Temperature on Development of Myzus persicae (Sulzer)

The effects of temperature on development of Myzus persicae (Sulzer) was investigated at five constant temperature 17, 20, 23, 26 and 29 ± 1 °C, 65 ± 5 % RH, and a photoperiod of 16:8 (L:D) hr fed on cabbage (Brassicae olerasia var. capitata) under laboratory condition using the age-stage, two-sex lifetable approach. The intrinsic rate of increase (r) of this aphid was highest at 29°C (0.3212 d-1) and lowest at 17°C (0.0.2157 d-1). The developmental rate of nymphs at different temperatures fit the linear equation, y= 0.005 x -0.001 with a coefficient of determination (R2) of 0.98. The thermal summation of the pre-adult, the female, and the total life stages (from birth to death) was 194.6, 241.8 and 430.2 DD, respectively. The developmental threshold of the pre-adult, the female, and the total life stage was 0.29, 10.6, and 5.29°C, respectively. The mean generation time was 18 d at 17°C, which declined to 10.2 d at 29°C. The net reproduction rate (R0) was 26.6 offspring/ individual at 29°C, and it was considerably lower than the rates obtained at other temperatures. The highest net reproductive rate was obtained at 20°C (R0= 54.2 offspring/ individual). In the absence of other limiting factors, populations of M. persicae would be expected to increase faster if introduced into environments having temperature ranging between 23 and 26 °C.

Nondetrimental impact of two concomitant entomopathogenic fungi on life history parameters of a generalist predator, Coccinella septempunctata (Coleoptera: Coccinellidae)

The non-persistent impact of biocontrol agents can be revealed for pest control when associated entomopathogenic fungi (EPFs) negatively affect the natural enemies. In this assay, impacts of Beauvaria bassiana (Balsamo) Vuillemin, and Metarhizium anisopliae (Metschnikoff) Sorokin were studied for their compatibility or side effects on life table parameters of an important generalist predator, Coccinella septempunctata L. The results indicated non-significant impacts of both EPFs on life table parameters of C. septempunctata. The development time (egg-adult) was not significantly different in control (69.79 days) and EPFs treated C. septempunctata (69.35–80.07 days). Both fungi did not induce any significant changes in the fecundity, adult pre-oviposition period (APOP), total preoviposition period (TPOP), and mean generation time (T) as compared to control treatment. Similarly, no difference in fecundity rate of C. septempunctata was observed after EPFs treatment (287.7–288.5) compared to control (290.0). The highest net reproductive rate (R0) occurred in control (87.05 offspring individual−1) and M. anisopliae (86.31 offspring individual−1) as compared to B. bassiana treated beetles (76.97 offspring individual−1). The age-specific fecundity curves indicated that the C. septempunctata had a similar fecundity rate in both EPFs treatments and control. This study demonstrates no significant side effects of B. bassiana and M. anispoliae on the performance and biology of C. septempunctata. Considering the compatibility of both EPFs with C. septempunctata, their combinations can be recommended in various integrated pest management programs.

Effects of temperature and supplementary food on the development and fecundity of the Eulophid parasitoid Tetrastichus howardi on Spodoptera frugiperda (Lepidoptera: Noctuidae)

Tetrastichus howardi (Olliff), a pupal endoparasitoid of the major agricultural pest Spodoptera frugiperda (J.E. Smith). Laboratory studies were conducted to determine the effect of the temperature and supplementary food on the development and reproduction of this parasitoid on S. frugiperda pupae. The results revealed that T. howardi could complete the life cycle under all five tested temperatures (18, 22, 26, 30 and 34 °C), with the most extended longevity (female: 42.83 days; male: 24.37 days) and the most prolonged developmental duration (egg-adult) (52.33 days) at 18 °C. Parasitoids that were kept at 26 °C had the greatest parasitism rate (72.67%) and the highest net reproductive rate R0 (56.35), and those maintained at 34 °C had the highest emergence rate (92.03%), the greatest number of emerged progeny (58.40) and the highest intrinsic rate of increase rm (0.310 d−1). Feeding on honey, glucose, and sucrose significantly increased the adult longevity and the progeny production of T. howardi but showed no significant effects on parasitism rate, emergence rate, the developmental duration of progeny, or sex ratio. Parasitoids that fed on glucose lived the longest (21.23 days), and the highest emerged offspring occurred when honey is provided (57.77). These results are instructive for the mass-rearing of T. howardi and field control of S. frugiperda.