F. S. Ramalho

Age-dependent fecundity and life-fertility tables for Podisus nigrispinus (Dallas) (Het., Pentatomidae)

Abstract: The reproductive potential and longevity of Podisus nigrispinus (Dallas) were determined under laboratory conditions at a constant temperature of 25°C. The data were used to calculate life‐fertility tables and rates of increase. The fecundity plateau of P. nigrispinus lasted 18 days, and during this period mean fecundity was 8.89 eggs per female per day. It started at the eighth day of age and ended at the 18th day of age. The declining fecundity period started at 18 days of age and ended with the death of the females. The female of P. nigrispinus oviposited a mean of 188.54 eggs, and had a mean longevity of 31.21 days. The gross reproductive rate (GRR) was 104.374 females/female; the net reproductive rate (Ro) was 31.945 females/female; the generation time was 47.390 days; the doubling time was 9.480 days; the intrinsic rate of increase (rm) was 0.073, and the finite rate of increase (λ) was 1.076. The predator population increased by 16.61 adult progeny per female per generation in the laboratory.

Effects of plant feeding on the development, survival and reproduction of Podisus nigrispinus (Dallas) (Heteroptera : Pentatomidae)

Diets consisting of leaves of cotton and/or water were insufficient to promote the complete development and survival of Podisus nigrispinus (Dallas) to the adult stage. However, nymphs fed leaves lived longer than those provided with only water. Addition of Alabama argillacea (Huebner) larvae to the diet of P. nigrispinus added a substantial increment to the survival during the nymphal stage. The addition of cotton leaves to the diet of P. nigrispinus nymphs promoted an increase in the weight of newly eclosed adults, independent of predator sex. In addition, diets supplemented with cotton leaves promoted an increase in the duration of the oviposition period, the number of egg clutches per female, and the number of eggs per female. No effects were noted on either the duration of the pre-oviposition period, the number of eggs of the first clutch, the number of eggs per clutch, the interval between egg clutches, or sex ratio. Feeding on plant material by P. nigrispinus is a potentially positive attribute in biological control against cotton leafworm.

Effect of temperature on life table parameters of Podisus nigrispinus (Het., Pentatomidae) fed with Alabama argillacea (Lep., Noctuidae) larvae

Abstract: The influence of temperature on life table parameters of Podisus nigrispinus (Dallas) (Het., Pentatomidae) fed with Alabama argillacea (Hübner) (Lep., Noctuidae) larvae was studied. This predator was kept at constant temperatures of 20, 23, 25, 28, 30 and 33±0.2°C, at relative humidity of 60±10% and photoperiod of L : D 14 : 10. Gross (GRR) and net (R0) reproductive rates of P. nigrispinus ranged from 1.6 to 366.6 and from 0.02 to 189.5 females/female at temperatures of 33 and 28°C, respectively; generation time (T ) ranged from 33.3 (33°C) to 85.5 (20°C) days; doubling time (D) from 0.82 (33°C) to 17.8 (20°C) days; intrinsic rate of increase (rm) from −0.13 (33°C) to 0.12 (28°C) per day; and the finite rate of increase (λ) from 0.88 (33°C) to 1.12 (28°C) females/female added to the population per day. The ideal age to release P. nigrispinus should be when this predator presents higher reproductive values (VRx); that is, its adults are about 7 days old, independent of prevailing temperature. Population growth of P. nigrispinus was affected by temperature with maximum numerical response between 28 and 30°C. The negative population growth shown at 33°C may not occur in natural conditions due to milder microclimate in the cotton agroecosystem and due to oscillations of temperature in the course of the day.

Effects of diet on development of Podisus nigrispinus (Dallas) (Het., Pentatomidae), a predator of the cotton leafworm

Abstract:  The effects of diet on development of Podisus nigrispinus (Dallas) (Het., Pentatomidae) were studied at 25°C, relative humidity of 60 ± 10%, and photoperiod of 14 h light : 10 h dark. Development times of P. nigrispinus nymphs were similar when fed with third or fifth instar larvae of cotton leafworm (Alabama argillacea Hübner) (Lep., Noctuidae) or Tenebrio molitor L. (Col., Tenebrionidae). When fed with housefly larvae (Musca domestica L.) (Dipt., Muscidae) or artificial diet, the predator had a longer development time. Independent of diet, instar or sex, the females of P. nigrispinus showed a longer longevity than the males. The total survival of the nymphal stage, on the different diets, varied from 22.46 (fed with housefly) to 77.33% (fed with T. molitor larvae). P. nigrispinus males were heavier when fed with third or fifth instar cotton leafworm larvae than when fed with artificial diet. The weight of the females varied from 37.91 (with artificial diet) to 64.68 mg (with fifth instar cotton leafworm larvae). Independently of the diet, newly emerged females of P. nigrispinus were heavier than the males. Females of P. nigrispinus which were fed with fifth instar cotton leafworm larvae had heavier ovaries than those fed other diets.

Morphology of female reproductive tract of the predator Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) fed on different diets

Este estudo apresenta a morfologia do sistema reprodutor feminino de Podisus nigrispinus (Dallas) alimentado com larvas de Alabama argillacea (Hubner), Musca domestica L. e de Tenebrio molitor L. ou dieta artificial. As gonadas internas desse predador apresentaram coloracao amarelada e, independente da dieta, cada ovario apresentou sete ovariolos unidos pelos filamentos terminais em uma estrutura em forma de cacho. A analise histologica revelou que o ovario de P. nigrispinus e do tipo meroistico telotrofico com cada ovariolo dividido morfologicamente em filamento terminal, trofario (câmara nutridora), vitelario e pedicelo. A dieta recebida por esse predador alterou o desenvolvimento e a morfometria de seus ovarios. Femeas de P. nigrispinus alimentadas com larvas de terceiro ou quinto estadio de A. argillacea apresentaram ovarios desenvolvidos com grande numero de ovocitos em estagio avancado de desenvolvimento nos ovariolos. Femeas com dieta artificial apresentaram ovarios atrofiados e ovariolos, praticamente, sem ovocitos em seu interior enquanto aquelas alimentadas com larvas de T. molitor ou M. domestica tiveram ovarios em estagios intermediarios de desenvolvimento. O comprimento do ovariolo central foi maior em femeas alimentadas com larvas de quinto estadio de A. argillacea e menor naquelas com dieta artificial. Ovocitos em estagios mais avancados de desenvolvimento foram observados para femeas alimentadas com larvas de terceiro ou quinto estadios de A. argillacea, enquanto ovocitos atrofiados foram observados para aquelas com dieta artificial.

Predation rate of Spodoptera frugiperda (Lepidoptera: Noctuidae) larvae with and without defense by Podisus nigrispinus (Heteroptera: Pentatomidae)

Objetivou-se determinar o efeito da defesa da presa Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) na taxa de predacao por femeas de Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae). Podisus nigrispinus, predou 1,0; 1,4; 1,2; 3,8; 3,0 lagartas de terceiro estadio de S. frugiperda com defesa, respectivamente, nas densidades de uma, duas, quatro, seis e oito lagartas, enquanto esses valores foram de 0,4; 0,8; 1,6; 2,8; 3,2 lagartas sem defesa, respectivamente, nessas densidades. A taxa de ataque (a) e o tempo de manipulacao (Th) foram, respectivamente, de 0,67 ± 0,39-h e 6,72 ± 2,88 horas para femeas de P. nigrispinus alimentadas com lagartas com defesa e de 2,51 ± 0,16-h e 0,51 ± 0,77 horas para aquelas sem defesa. A resposta funcional do predador P. nigrispinus varia com a defesa e a densidade da presa S. frugiperda, com maior consumo de presas sem defesa em altas densidades.

Reproductive performance of Palmistichus elaeisis Delvare and LaSalle (Hymenoptera: Eulophidae) with previously refrigerated pupae of Bombyx mori L. (Lepidoptera: Bombycidae)

The mass rearing of parasitoids represents a fundamental stage for programmes of biological control. The progeny of the parasitoid Palmistichus elaeisis Delvare and LaSalle (Hymenoptera: Eulophidae) were evaluated on previously refrigerated pupae of Bombyx mori L. (Lepidoptera: Bombycidae). Forty-eight to 72 hours-old pupae of B. mori were stored at 10 degrees C for five, 10, 15 or 20 days and then exposed to parasitism by P. elaeisis females. This parasitoid showed shorter duration of the life cycle when reared on pupae of B. mori which were previously stored at 10 degrees C during 15 days. P. elaeisis parasitized 100% of the pupae of B. mori after storage at 10 degrees C during all periods with emergence of this parasitoid from 78 to 100% of these pupae. P. elaeisis had a higher number of progeny per pupa of B. mori stored for 15 days at 10 degrees C. Pupae of B. mori can be stored for 15 days at 10 degrees C before being used to rear P. elaeisis.

Effect of diet on male reproductive tract of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae)

The morphology and histology of the reproductive tract of males of the predator Podisus nigrispinus (Dallas) fed on different diets were studied. P. nigrispinus was fed on diets of: larvae of Alabama argillacea (Hübner), Tenebrio molitor L., Musca domestica L., and an artificial diet. The male reproductive tract, independent of diet, showed testes with intense red coloration in a compact, circular, or slightly oval structure. The vasa deferentia were similar in color to the testes and formed long filaments, which joined with the yellow-cream colored ejaculatory duct. The morphological characteristics of the male reproductive tract were similar under all diets, except for the artificial one. The histological studies demonstrated that independent of the diet the testes of P. nigrispinus were composed of four to six follicles. The testes with six follicles generally had four developed and two atrophied follicles. The morphological and histological differences of the testes of P. nigrispinus when fed with different prey are presented and discussed.

Kaolin spraying protects cotton plants against damages by boll weevil Anthonomus grandis Boheman (Coleoptera: Curculionidae)

The high cost of insecticides, the emergence of insecticide resistance in populations of a number of insect species and other problems arising from their continuous use, such as biological imbalance, cotton fiber waste, and environmental pollution, have prompted the development of new technologies aiming the control of Anthonomus grandis Boheman in cotton crops. This study evaluated the level of protection conferred by kaolin clay foliar spraying to cotton plants against boll weevil damage. Treatment-tested spraying kaolin or endosulfan on cotton plants. The highest percentage of oviposition-punctured squares were observed in the control, and the lowest percentages in the treatments sprayed with endosulfan and kaolin in a systematic manner and where the boll weevil reached the economic threshold at all assessments. The greatest numbers of non-attacked bolls by weevils and cotton-seed yield were observed under the endosulfan treatments, followed by the treatments of kaolin spraying. The smallest number of bolls and lowest cotton-seed yield were observed for the control plots. These finding are of practical significance because they may reduce the cotton production cost and environmental impacts of chemical pesticides and make possible the production of organic cotton with the presence of boll weevils.

Estimate of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) development with nonlinear models

The objective of this work was to evaluate which nonlinear model [Davidson (1942, 1944), Stinner et al. (1974), Sharpe & DeMichele (1977), and Lactin et al. (1995)] best describes the relationship between developmental rates of the different instars and stages of Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), and temperature. A. argillacea larvae were fed with cotton leaves (Gossypium hirsutum L., race latifolium Hutch., cultivar CNPA 7H) at constant temperatures of 20, 23, 25, 28, 30, 33, and 35 masculine C; relative humidity of 60 +/- 10%; and photoperiod of 14:10 L:D. Low R(2) values obtained with Davidson (0.0001 to 0.1179) and Stinner et al. (0.0099 to 0.8296) models indicated a poor fit of their data for A. argillacea. However, high R(2) values of Sharpe & DeMichele (0.9677 to 0.9997) and Lactin et al. (0.9684 to 0.9997) models indicated a better fit for estimating A. argillacea development.