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1.
The biology and predatory efficiency of Geocoris ochropterus Fieber (Hemiptera: Geocoridae) has been studied extensively against many insect pests, but information on functional response of different stages of G. ochropterus to Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is lacking so far. The functional response of different stages of G. ochropterus to varying densities of eggs of H. armigera was investigated in the laboratory at 26?±?2°C, 65?±?2% RH and 12 L: 12D. Immature stages i.e. 3rd, 4th, 5th instar and adult predator exhibited type II functional response. Handling time decreased with increasing predator’s developmental stage. Adult G. ochropterus followed by fifth instar exhibited highest egg consumption and attack rate compared to other stages. Functional response parameters indicate that the adult and fifth instar of G. ochropterus were more voracious and efficient than other juveniles and might be useful as promising biocontrol agent against H. armigera.  相似文献   

2.
Functional response of Harmonia dimidiata (Fab.) to melon aphid, Aphis gossypii Glover was studied in the laboratory at 25 ± 0.5 °C, 70 ± 5% RH and 12L:12D photoperiod. All the predator stages exhibited Type II functional response to the aphid. Based on Rogers’s random predator equation the predator’s attack rate was lowest (0.128) in the first-instar and highest (0.21) in the adult stage. Handling times of the adult beetle and the fourth-instar (0.148 and 0.164 h, respectively) were much shorter than other stages. The maximum number of aphids that could be consumed over a period of 24 h by first, second, third and fourth instar; and adult of H. dimidiata was estimated to be 47.2, 80.2, 79.7, 146.2 and 161.7 aphids/ predator. Functional response parameters indicate that the adult beetles and the fourth-instar were the most voracious stages and could be important for the biological control of the aphid.  相似文献   

3.
Aenasius arizonensis (Girault) (Hymenoptera: Encyrtidae) is an important solitary endoparasitoid of mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae). Studies on seasonal and biological interactions between host and parasitoid are important to optimize the mass production and field release of high-quality females. We investigated the influence of different crop seasons viz., pre-monsoon, monsoon and post-monsoon and host stages viz., three nymphal instars (1st, 2nd and 3rd) and adult stage of P. solenopsis on the development, longevity, fecundity and sex ratio of its parasitoid, A. arizonensis. A. arizonensis female parasitized all life stages of its host except the 1st instar nymphs. Only males emerged from parasitized 2nd instar nymphs, while the sex ratio in the later host instars was strongly female-biased. The adult host stage was most suitable for A. arizonensis in terms of shorter development time, while the 3rd instar nymphal stage was most suitable with respect to higher fecundity, proportion of adults emerged and more females in the progeny. Among different seasons, post-monsoon season (September–October) with temperature (25 to 29 °C) and relative humidity (68 to 73%) was most suitable for the overall fitness of the parasitoid. The findings of this study have implications in designing mass rearing of this parasitoid and devising an effective biological control strategy for P. solenopsis on cotton.  相似文献   

4.
Dactylopius opuntiae is an insect pest of cactus which is currently causing severe damage to cactus crops in Morocco. It was first observed in 2014 in the Sidi Bennour region 120 km northwest of Marrakech, and has spread very quickly to destroy the prickly pear cactus crops (Opuntia ficus‐indica (L.) Miller) in several regions of country, causing very heavy economic losses. To control this pest, the predatory potential of eleven species of native Moroccan ladybird predators was investigated under laboratory conditions at 26 ± 2°C, 60 ± 10% RH and a 12 h light:12 h dark regime. The experiments were conducted in no‐choice feeding tests (only eggs, first instar or second instar of mealybugs were offered at one time) and free‐choice feeding tests (eggs and first and second instar larvae were offered simultaneously). In the no‐choice feeding tests, Exochomus nigripennis, Chilocorus bipustulatus and Chilocorus politus consumed the highest mean number of mealybug eggs and first instars, and the highest mean number of second instars was consumed by Hippodamia convergens. In the free‐choice feeding tests the highest mean number of mealybug eggs was eaten by Chilocorus bipustulatus and Chilocorus politus and Hippodamia convergens consumed the highest mean number of first and second instars of the mealybug.  相似文献   

5.
The citrus mealybugPlanococcus citri (Risso) and the vine mealybugPlanococcus ficus (Signoret) (Hemiptera: Pseudococcidae) are two worldwide polyphagous pests of citrus, vineyards and ornamental plants in greenhouses. Biological control of these pests may rely on the combined release of parasites and predators, which can be affected by intraguild predation (IGP). This study investigated the feeding behavior of different stages ofCryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) on mealybugs parasitized byAnagyrus pseudococci (Girault) (Hymenoptera: Encyrtidae) 2, 4, 6, 8 and 10 days. The study was conducted in a climate-controlled room at 28±1° C, 16L:8D, and 65±10% r.h. The highest consumption values for all stages ofC. montrouzieri occurred with 2- and 4-day parasitized mealybugs, whereas the predator did not feed on either species of mealybug parasitized for longer periods, due to the onset of mummification. http://www.phytoparasitica.org posting August 4, 2008.  相似文献   

6.
Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is an exotic species native to the USA, damaging cotton and other plant families. The feeding potential of different development stages of Cryptolaemus montrouzieri Mulsant, a biological control agent against mealybugs, was investigated on different development stages of P. solenopsis. Fourth instar grubs and adults of C. montrouzieri were the most voracious feeders on different instars of mealybug. The number of 1st instar nymphs of mealybug consumed by 1st, 2nd, 3rd and 4th instar larvae and adult beetles of C. montrouzieri was 15.56, 41.01, 125.38, 162.69 and 1613.81, respectively. The respective numbers of 2nd and 3rd instar nymphs of mealybug consumed were 11.15 and 1.80, 26.35 and 6.36, 73.66 and 13.32, 76.04 and 21.16, 787.95 and 114.66. The corresponding figures for adult female mealybugs were 0.94, 3.23, 8.47, 12.71 and 73.40, respectively. The results indicate that C. montrouzieri has the potential to be exploited as a biocontrol agent in North India; inoculative releases of 4th instar larvae and adults may provide instant control of P. solenopsis. Field experiments should be conducted to determine the efficiency of the ladybird on this mealybug.  相似文献   

7.
The functional response types and parameters of 3rd and 4th instar larvae, and adult females and males of a coccinellid predator, Adalia fasciatopunctata revelierei (Mulsant) (Col.: Coccinellidae), were evaluated at five different densities of Callaphis juglandis (Goeze) (Hemiptera: Aphididae) in order to understand their role for the aphid’s biological control. Experiments were carried out in petri dishes at 25 ± 1°C, 60 ± 10% r.h. and 16L:8D photoperiod in a controlled temperature room. All tested stages exhibited a Type II response determined by a logistic regression model. The attack rate (α) and handling time (T h ) coefficients of a Type II response were estimated by fitting a “random-predator” equation to the data. Although the estimates of α for all stages of A. fasciatopunctata revelierei tested were similar, the longest T h was obtained for 3rd instar larva because of the lower consumption rate at densities above 40 prey/day. Results indicated that the adult female has the highest predation of C. juglandis followed by 4th instar larvae, adult males and 3rd instar larvae. However, further field-based studies are needed to draw firm conclusions.  相似文献   

8.
The pink hibiscus mealybug Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae) is a major pest of economically important crops. The apefly Spalgis epius (Westwood) (Lepidoptera: Lycaenidae) is a potential predator of various species of mealybugs. Studies of its preying potential and preference for prey stages on M. hirsutus are incomplete. An investigation was undertaken to determine the daily prey consumption and preference for prey stages by different larval instars of S. epius reared on M. hirsutus in the laboratory. During the 8-day larval development period with four larval instars of S. epius, the daily prey consumption increased from the first to the seventh day and decreased on the eighth day prior to the prepupal stage. Generally, there was a significant difference in the prey consumption on different days. The 1st to 4th instar larvae of S. epius consumed, respectively, a mean of 181.3, 679.1, 1770.4 and 4333.0 eggs or 19.1, 67.7, 153.0 and 639.0 nymphs or 2.72, 6.26, 13.8 and 32.1 adults of M. hirsutus. When an S. epius larva was fed on M. hirsutus eggs, nymphs and adults separately, it consumed a mean of 6952.6 eggs, 878.8 nymphs or 53.9 adults during its entire development. A single larva of S. epius consumed 2358.3 eggs, 151.2 nymphs and 34.3 adults of M. hirsutus during its entire development when the prey stages were offered all together. The study revealed that S. epius is a voracious predator of M. hirsutus and thus could be utilized as a potential biological control agent.  相似文献   

9.
The vine mealybug, Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae), is one of the main pests in vineyards. At present biological control of the pest is based on the release of hymenopterous parasitoids and coccinellid predators. The effectiveness of an entomopathogenic fungus, Isaria farinosa, as an alternative biological control agent on vine mealybug P. ficus was investigated by using different inoculum densities and different relative humidity levels. The fungus caused more than 80% mortality at 95% relative humidity and at 1 × 108 conidia ml?1 inoculum density. The mortality effects of the fungus decreased in lower humidity levels and lower spore densities. The inhibitory effects of common fungicides, used in vineyards, on I. farinosa were also investigated. Sulphur, copper oxychloride, fosetyl-Al and chlorothalonil did not decrease the effectiveness of I. farinosa as a pathogen of vine mealybug. With the application of tebuconazole, penconazole and mancozeb, the most inhibitory fungicides on the entomopathogen, the mortality rates of mealybugs, inoculated with I. farinosa, decreased from 86% to 42%, 34% and 45%, respectively, in the adult females; from 94% to 51%, 45% and 45%, respectively, in the first nymphal stages; and from 86% to 56%, 49% and 63%, respectively, in ovisacs.  相似文献   

10.
The antifungal properties of two phosphonates (fosetyl-Al and a fertilizer) and acibenzolar-S-methyl (ASM) were evaluated to assess their potential for protecting grapevine leaves against grapevine mildews (Plasmopara viticola and Erysiphe necator), and to determine their effects on the development of various mildew isolates, taking into account the inter- and intra-species variability of the pathogens. The phosphonates directly and significantly inhibited the growth of these pathogens. By contrast, ASM had no direct effect on spore production and growth of P. viticola and of E. necator at 1.9 mM. Applied before inoculation, the mean EC50 of ASM was 0.50?±?0.04 mM and 1.00?±?0.07 mM for downy and powdery mildew isolates, respectively. The EC50 of the fosetyl-aluminium (FOS) was 0.50?±?0.02 mM for downy mildew and the EC50 for powdery mildew varied depending on the genetic group under consideration (0.89?±?0.32 mM for group B 3.30?±?0.46 mM for group A, respectively). The EC50 of the potassium phosphonate fertilizer (PK2) was 0.96?±?0.45 mM for downy and 6.9?±?0.76 mM for powdery mildew isolates. These compounds showed differences in their efficacy depending on the variability of mildews and could be an alternative or additional method to traditional pest management in the grapevine.  相似文献   

11.
Rph20 is the only designated gene conferring adult plant resistance to leaf rust in barley, and to date, it has not displayed race specificity. It is not known at what particular growth stage the onset of Rph20 resistance occurs, or if the expression of the gene could be observed in controlled greenhouse assays. The present studies demonstrated that Rph20 can be identified reliably under greenhouse conditions in 5-week-old seedlings under normal temperature conditions (22?±?2 °C), although the resistance becomes effective at 4 weeks in certain genetic backgrounds. The resistance conferred by Rph20 was strongest and best expressed at cooler temperatures (18?±?2 °C). The effectiveness of Rph20 at cooler temperatures may have important implications in the epidemiology of barley leaf rust under field conditions, by preventing the carryover of inoculum through winter and early spring, leading to a delayed onset of rusting and subsequently lower, if any, yield losses. The detection of Rph20 in early growth stages could help simplifying the selection of the gene in breeding programs and in monitoring Puccinia hordei populations for pathogenicity.  相似文献   

12.
Hungariella (Tetracnemus) peregrina Compere 1939 is an internal parasite of the long-tailed mealybugPseudococcus longispinus (Targ. Tozz.) (=P. adonidum L.), which attacks the mealybug chiefly in instars I and II. Development through the egg, larval and pupal stages lasts an average of 29.75 days at 30°C and 79.54 days at 17°C. The sex ratio is 1.3 females to 1 male. The wasp persists in avocado orchards throughout the year and overwinters inside the mealybugs or as an adult. The survival depends on the level and duration of low temperatures, since the wasp's tolerance of high temperatures increases as humidity rises, and high humidity greatly increases the life span. In none of the above respects were females found to differ significantly from males.  相似文献   

13.
Metarhizium guizhouense PSUM02 treated males of Bactrocera latifrons were investigated for the mating competition among males and mating choice by female flies to develop an auto-dissemination for the control of B. latifrons. In the present study, on day 1–4 of experiment, M. guizhouense–treated male flies were equally competitive with the normal male flies as we did not observe any differences in mating by treated and normal male flies of B. latifrons. Further, mating competitiveness were found low in treated adult male B. latifrons than normal male B. latifrons from 5th days of treatment until death. Kaplan-Meier survival analysis of treated male flies gave average survival times (AST) of 4.3?±?0.1 days, while the healthy female and male flies in the same cage showed AST of 9.3?±?0.3 and 8.3?±?0.4 days, respectively. The AST of untreated flies in control experiment ranged from 14.2–14.5 days. In mating preference experiment, M. guizhouense–treated male flies were chosen by virgin female than gravid female flies for mating. The treated male flies caused mortality in both virgin and gravid female flies in the same cage with AST of 4.4?±?0.1, 5.6?±?0.1 and 7.4?±?0.2 days, respectively, while untreated flies showed AST ranged from 13.9–14.3 days in control. The treated male flies could transmit the fungus infection to both untreated female and male flies as well as in virgin and gravid female flies by mating and contact. Our experiments showed the potentiality of M. guizhouense PSUM02 in management of B. latifrons by auto-dissemination with treated male flies, which transmit the fungus to a healthy population to reduce insect pest infestations.  相似文献   

14.
Morphological characteristics of immature developmental stages of Rhyzobius lophanthae Blaisdell (Col.: Coccinellidae), predator of scale insects of the family Diaspididae (Homoptera), are described. Data about the morphology of eggs, the four larval instars, and the pupa is presented. Larval instars are described in more detail: size of head capsule, length of tibia, distribution of dorsal and lateral setae of abdomen segments for each larval instar is reported. Distribution of spiracles is also given. Study on the biology concerns the influence of prey on the duration of instar periods. The diaspidids Aspidiotus nerii and Aonidiella aurantii were used as food. The mean duration of the developmental period from egg to adult was 27.1 days, and no mortality was observed (0%) when A. nerii was used as prey. The respective numbers when the prey was A. aurantii were 48.8 days and 84%.  相似文献   

15.
Helicoverpa armigera is a strong insecticidal resistance developed insect pest. The understanding of its innate immune responses to emerging biocontrol agent entomopathogenic nematode-bacterial complex can provide an opportunity to control this insect in an environmentally benign manner. Study was focused on role of hemocytes changes and PO activity in Steinernema abbasi-Xenorhabdus indica challenged larvae of H. armigera over the time. Total cell count changed effectively from 10.2?±?1.81?×?105 to 15.5?±?3.3?×?105 cells/mm3 upto 9 h and reduced distinctly up to 8.0?±?2.49?×?105 cells/ mm3 in 24 h. PO activity inclined significantly and was recorded highest at 9 h (24.67?±?1.08?×?102 units) and lowest at 24 h (14.34?±?0.74?×?102 units) in total hemolymph with a similar pattern in plasma and the cellular fraction. Phenoloxidase activity in total and cellular component of hemolymph was positively correlated with prohemocytes, granulocytes and oenocytoids. Study showed the hemocytes and PO accounted as active immune responses against nematode infection. The results provide the first insight to understand the hemolytic activity, quick immunosuppression responses of S. abbasi-X. indica and vulnerability of H. armigera.  相似文献   

16.
Helopeltis theivora Waterhouse (Heteroptera: Miridae) is a major sucking insect pest of tea (Camellia sinensis) which feeds on a wide variety of alternative host plants. Feeding biology and fitness traits of H. theivora, on two alternative host plants, viz., Mikania micrantha (Asteraceae) and Psidium guajava (Myrtaceae), besides C. sinensis (Theaceae), were studied along with corresponding levels of xenobiotic defense enzymes. C. sinensis is the preferred host of H. theivora. The development time of H. theivora is significantly shorter on C. sinensis (13.3?±?0.16?days) than on the two other hosts, M. micrantha (14.2?±?0.22?days) and P. guajava (14.7?±?0.23?days). Similarly, the fecundity (C. sinensis: 172.6?±?4.5 eggs/female, M. micrantha: 128.6?±?4.4 eggs/female, P. guajava: 118.7?±?3.3 eggs/female), oviposition period (C. sinensis: 24.1?±?0.7?days, M. micrantha: 22.5?±?0.6?days, P. guajava: 21.7?±?0.8?days) and hatchability (C. sinensis: 80.9?±?1.9%, M. micrantha: 69.4?±?1.6%, P. guajava: 64.1?±?1.7%) are recorded to be significantly higher on C. sinensis. The age at reproductive maturity and egg incubation periods were lower on C. sinensis than on the two other host plants. Host-based variation in H. theivora fitness traits is interpreted in light of differential activity of three principal xenobiotic detoxifying enzymes, the general esterases (GEs), glutathione S-transferases (GSTs) and cytochrome P450 monooxygenases (CYPs). The activities of these enzymes in H. theivora were significantly enhanced when the insect fed on M. micrantha and P. guajava as compared with on C. sinensis.  相似文献   

17.
We investigated the suitability of six mealybug species, namely Phenacoccus solenopsis, Saccharicoccus sacchari, Paracoccus marginatus, Drosicha mangiferae, Nipaecoccus viridis and Ferrisia virgata as hosts to Aenasius arizonensis ( = Aenasius bambawalei). The study was conducted to ascertain a viable parasitic relationship between a parasitoid species and different mealybug hosts. Successful parasitization, complete development of immature stages within the host and adult emergence was observed only in P. solenopsis, whereas, other mealybug species were not found suitable as hosts by the parasitoid in both choice and no-choice tests. The development studies of A. arizonensis on P. solenopsis showed that the mean duration from oviposition to mummy formation was 6.13 days, while, from mummy formation to adult emergence, it was 5.43 and 7.05 days for male and female, respectively. The total development period from oviposition to adult emergence was 11.28 days for males and 13.13 days for females. Female adults (19.96 days) live longer as compared to male adults (7.83 days). Among different mealybug species, P. solenopsis was observed to be the only ecological and fundamental host of A. arizonensis.  相似文献   

18.
Control of the invasive vine mealybug Planococcus ficus (Signoret) can be achieved through integration of different management strategies such as the application of chemical treatments and biological control. However, compatibility between these control methods is considered crucial when adopting integrated pest management (IPM) programs against this insect pest. The recently used insecticides Prev-Am®, a contact biopesticide, and spirotetramat, a systemic tetramic acid insecticide, were assessed in laboratory conditions for their side effects on the vine mealybug parasitoid Anagyrus sp. near pseudococci with reference to chlorpyriphos-methyl, an organophosphate insecticide conventionally used for mealybug control in vineyards. Regarding contact toxicity, chlorpyriphos-methyl caused 100% parasitoid mortality 24 h after treatment, but parasitoid mortality from Prev-Am® or spirotetramat was almost absent. Neither the total parasitoid offspring/female nor the sex ratio of the progeny was negatively affected by Prev-Am® or spirotetramat relative to the untreated control. According to the IOBC classification for laboratory trials, both Prev-Am® and spirotetramat were rated harmless (IOBC category 1), whereas chlorpyriphos-methyl was categorized as harmful (IOBC category 4) to A. sp. near pseudococci. None of the insecticides adversely affected the development of the parasitoid pupal stage inside mealybug mummies or the survival of the emerged parasitoids. The practical implications of the results for implementing mealybug IPM programs in vineyards are emphasized and discussed.  相似文献   

19.
Leucopholis coneophora Burmeister is a subterranean pest associated with coconut based cropping systems in south India. Feeding damage causes yellowing of fronds and yield reduction. To develop appropriate IPM strategy a basic knowledge on insect behaviour is essential. Four years studies indicated that, adult emergence of L. coneophora was commenced with summer shower in April in Kerala. Delay in summer shower delayed the emergence. After a pause in May, the emergence resumed with the setting of south west monsoon in June. The beetles did not emerge during dry spells in between the rainy days, when the soil temperature (at 10 cm depth) was ≥34.5 °C. Emergence of the beetles started at an illuminance of 124.37?±?75.5 l in evening and remained active till 2?±?0.4 l with a maximum swarming at 32.6?±?15.1 l. Female emergence and mating occurred at 12.04?±?8.1 l. Female based sex pheromone mediated communication is evident. Strong competition among the males for mating with emerging female, which was evident by a wider operational sex ratio in the initial period (1:10.11) that narrowed down to 1:4.33 in later days. The beetles neither congregate on any host plant nor exhibit phototaxis. Number of beetles entrapped in light traps varied from 1.5–16.5% and hand picking is highly significant over light trapping. Hence hand picking of beetles daily in the evening for 2 weeks commencing from the onset of south west monsoon in Kerala, in Indian subcontinent is suggested as a tool in IPM.  相似文献   

20.
The maize weevil Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) is a worldwide pest on stored products, as maize, wheat and rice grains. However, in South Brazil, these weevils have been found attacking fruits in field conditions. It was reported that adults attack fruits to feeding, but there was no information of oviposition and larval development on these hosts. Furthermore, due to monitoring apple orchards, was observed that some fruits showed distinct kind of punctures, suggesting a oviposition by these weevils. The present study reports first record an unusual behavior of S. zeamais by oviposition and larval development in peach and apple fruits. The study was conducted in laboratory conditions (temperature: 25?±?1 °C, RH: 70?±?10% and photophase of 14 h). Peach and apple fruits were offered to S. zeamais females. The oviposition and duration of immature stages in peach were measured in fruits and in corn grains, used as control observation. The oviposition and larval development occurred in peach and apple fruits, with a development until to adult. The average of egg-to-adult was 47.4 d in peach and and 45.1 d apple fruits, respectively, while in corn grains, its natural host, the duration was 38.2 d. These results show that the damage caused by S. zeamais in peach and apple fruits may be due to oviposition and the development of immature stages. So, the novelty is in demonstrating that the maize weevil does not just feed as an adult opportunistically on the fruits, but can complete a full life cycle using fresh fruits.  相似文献   

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