Facultative Hyperparasitism: Extreme Survival Behaviour of the Primary Solitary Ectoparasitoid, Dinarmus basalis

This study investigated the egg-laying behaviour of ectoparsitoid, Dinarmus basalis Rondani (Hymenoptera: Pteromalidae), females when faced with a prolonged deprivation of suitable hosts leading to extreme ‘oviposition pressure’. The egg-laying behaviour of virgin D. basalis females was tested with Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) hosts previously parasitized by the conspecific females in which the developing larvae had reached the last larval instar (L5) or pupae. The hyperparasitism did not prevent the occurrence of superparasitism, but only one D. basalis egg from a hyperparasitized D. basalis L5 larvae reached the adult stage due to the solitary behaviour of the D. basalis larvae. Under these experimental conditions, 60.78% of the D. basalis adults emerging from larvae were miniaturized due to the depletion of host resources

Soil organisms associated to the weed suppressant Crotalaria juncea (fabaceae) and its importance as a refuge for natural enemies

Soil organisms play an important role in organic crops of Crotalaria juncea (Fabaceae) and are associated with the natural conservation of the environment. The present study was aimed to investigate the population of soil organisms in the organic culture of C. juncea, as well as its importance as a refuge for natural enemies. Dalbulus maidis (Hemiptera: Cicadellidae), Diabrotica sp. (Coleoptera: Chrysomelidae), Doru luteipes (Dermaptera: Forficulidae), Gryllus assimilis (Orthoptera: Gryllidae), Lagria villosa (Coleoptera: Lagriidae), Melanotus sp. (Coleoptera: Elateridae), Meloidogyne incognita (Tylenchida: Heteroderidae), Nephila clavipes (Araneae: Nephilidae), Orius insidiosus (Hemiptera: Anthocoridae), Pheidole sp. (Hymenoptera: Myrmicidae), Phyllophaga sp. (Coleoptera: Scarabeidae), Procornitermes sp. (Isoptera: Termitidae), Solenopsis sp. (Hymenoptera: Formicidae), and Utetheisa ornatrix (Lepidoptera: Arctiidae) were identified in C. juncea. The organisms that were found during a 3-month period in 144 trenches in C. juncea were pest species (84.47%) and natural enemies (15.53%) as well. Natural enemies had an average of 11.89 individuals per 1.08 m³ of soil cultivated with C. juncea. The abundance of organisms in the pod stage (5.49%) of C. juncea was lower than that in the vegetative (83.50%) and flowering (11.01%) stages. Crotalaria juncea plants can be used as part of a crop system for Integrated Pest Management.Organismos de solo desempenham um importante papel em cultivos orgânicos de Crotalaria juncea (Fabaceae) e estão associados com a conservação natural do ambiente. O presente estudo teve como objetivo investigar a população de organismos de solo no cultivo orgânico de C. juncea, bem como sua importância como um refúgio para inimigos naturais. Dalbulus maidis (Hemiptera: Cicadellidae), Diabrotica sp. (Coleoptera: Chrysomelidae), Doru luteipes (Dermaptera: Forficulidae), Gryllus assimilis (Orthoptera: Gryllidae), Lagria villosa (Coleoptera: Lagriidae), Melanotus sp. (Coleoptera: Elateridae), Meloidogyne incognita (Tylenchida: Heteroderidae), Nephila clavipes (Araneae: Nephilidae), Orius insidiosus (Hemiptera: Anthocoridae), Pheidole sp. (Hymenoptera: Myrmicidae), Phyllophaga sp. (Coleoptera: Scarabeidae), Procornitermes sp. (Isoptera: Termitidae), Solenopsis sp. (Hymenoptera: Formicidae) e Utetheisa ornatrix (Lepidoptera: Arctiidae) foram identificados em C. juncea. Os organismos que foram encontrados durante um período de três meses em 144 trincheiras em C. juncea foram as espécies de pragas (84,47%) e inimigos naturais (15,53%). Inimigos naturais tiveram uma média de 11,89 indivíduos por 1,08 m³ de solo cultivado com C. juncea. A abundância de organismos na fase de vagem (5,49%) de C. juncea foi menor do que nas fases vegetativa (83,50%) e floração (11,01%). Plantas de C. juncea podem ser usadas como parte de um sistema de cultivo para o Manejo Integrado de Pragas

Morphology and biometry of larval instars of <i>Pimpla instigator</i> (F.) (Hymen-optera: Ichneumonidae)

AbstractLarvae of Pimpla instigator (F.) were found to pass through five larval instars during development. Initial studies of external morphology identified only three morphological groups: the primary larva (L1) the intermediate larvae (L2−4) and the final instar larvae (L5). Biometrical study of the maximum head width, width of buccal mask, inter-metatentorial distance and diameter of spiracles permitted morphological separation of all five larval instars. Under a 16 h photophase (at 25±1°C; 70±10% r.h.) and an 8 h scotophase (at 15±l°C; 80±10% r.h.) the 2nd, 3rd and 4th larval instars were found to last about 24 h each, and the 5th instar 9±1 days. Progressive development of the genital buds during the 5th instar and prepupal stages facilitated sexing of the larvae.</jats:p

Reproductive potential in the parasitoid <i>Eupelmus orientalis</i> (Hymenoptera: Eupelmidae)

AbstractEupelmus orientalis (Crawford) (Hymenoptera: Eupelmidae) is a solitary ectoparasitoid of the larvae and pupae of West African bruchids. Since the biology of this species was unknown, studies were carried out on its reproductive biology. The age-dependent fecundity and offspring production of virgin and mated females of E. orientalis were determined under laboratory conditions at 33°C:23°C, 50%:80% r.h., L:D 12:12 on its host Callosobruchus maculatus (Fabricius) (Coleoptera: Bruchidae) during the first 15 days of the life cycle. No differences were found between virgin and mated females for any parameter. A study of the age-dependent fecundity and offspring production was also carried out under the same conditions over the entire life cycle of mated females. The resulting data were used to determine the longevity and reproductive potential of the species, particularly through the calculated life tables and estimation of the intrinsic rate of increase. With ten hosts per female per day, E. orientalis females had a mean longevity of 45.75±5.09 days. They laid an average of 219.91±39.08 eggs, parasitized 154.27±26.17 hosts, and produced 166.77±9.41 offspring, consisting of 80.46±14.10 males and 86.31±10.04 females. The total mean developmental time was 18.58±0.22 days for males and 20.03±0.21 days for females. The net reproductive rate (Ro) was 62.33 female progeny per adult female, and the intrinsic rate of population increase (rm) was 0.1389 per day. The generation time (G) was 29.76 days and the doubling time (DT) 4.99 days. These results constitute the first step to determine the potential of E. orientalis as an agent for the biological control of bruchidae, especially C. maculatus.</jats:p