eraldo lima

Two insect colonies of Elasmopalpus lignosellus were reared in our laboratory, the first being initiated from pupae obtained from a cornfield in the region of Sete Lagoas, Minas Gerais and the second from a cornfield in the region of Goiânia, Goiás. From the two colonies, two extracts were prepared from the pheromone glands of virgin E. lignosellus females. The extract obtained from the first colony was designated as extract 1 while the extract obtained from the second colony was designated as extract 2. Extract 1 was analyzed by gas chromatography-mass spectrometry (GC-MS) with (Z)-9-hexadecenyl acetate [(Z)-9-HDA] and (Z)-11-hexadecenyl acetate [(Z)-11-HDA] being identified and confirmed by the formation of DMDS derivatives. In addition, a third acetate, which could be either (E)-8-hexadecenyl acetate [(E)-8-HDA] or (E)-9-hexadecenyl acetate [(E)-9-HDA] was detected by GC-MS. Extract 2 was analyzed by gas chromatography (GC) and gas chromatography-electroannetography (GC-EAD) revealing the presence of (Z)-11-HDA and (Z)-9-TDA. In addition, the same compounds elicited a response with the E. lignosellus male antenna obtained from the second insect colony. Electroantennography (EAG) screening with the male E. lignosellus antenna (obtained from the second insect colony) was conducted with the 23 possible tetradecenyl acetates (TDA) and 22 hexadecenyl acetates (HDA) as standards. Out of the 23 TDA isomers evaluated, only (Z)-9-TDA elicited a response and out of the 22 HDA [(Z) and (E) isomers Δ2 to Δ13] evaluated only (Z)-11-HDA elicited a response. The acetate compositions of two extracts obtained from insects originating from the two states (Minas Gerais and Goiás) of Brazil were different from one another as well as from that obtained from insects in Tifton, GA, USA. The bioactivity data (GC-EAD) of the extract 2 differed from those reported for the Tifton, GA, USA population. These data suggest polymorphism in relation to the insect populations found in Brazil and in the USA. The possibility of the existence of an E. lignosellus sub-species cannot be ruled out.

Based on a specially created mass spectral database utilizing 23 tetradecenyl and 22 hexadecenyl acetate standards along with Kóvats retention indices obtained on a very polar stationary phase [poly (biscyanopropyl siloxane)] (SP 2340), (Z)-9-hexadecenyl acetate, (Z)-11-hexadecenyl acetate and (E)-8-hexadecenyl acetate were identified in active pheromone extracts of Elasmopalpus lignosellus. This identification was more efficient than our previous study using gas chromatography/mass spectrometry with a dimethyl disulfide derivative where we could only identify the first two acetates. The acetate composition of the pheromone gland differed from region to region in Brazil and from that from the Tifton (GA, USA) population, suggesting polymorphism or a different sub-species.

Among insects polyandrous behavior is common and plays an important role in female reproductive output. The present study aimed to evaluate the mating frequency of the moth Cerconota anonella Sepp under laboratory conditions and to verify if polyandrous behavior is common in this species. Approximately 47% of females mated more than once. However they presented differences in the mating period (early or late). In general, precocious females were more frequent than late females (P < 0.001, Binomial test). Such results suggest that polyandry in C. anonella may be common in the field.

The effect of nine insecticides used in tomato production was evaluated on adults of two Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) populations from Rive and Afonso Cláudio, Espírito Santo State, Brazil. The experiment was developed in an acclimatized chamber at 25 ± 1°C, 70 ± 10% relative humidity and 14 h photophase. Eggs of Anagasta kuehniella (Lepidoptera: Pyralidae), previously immersed in insecticides solutions were offered to females of both T. pretiosum populations. Bacillus thuringiensis, lufenuron and triflumuron had lowest negative effects on parasitism and viability of individuals of these populations; however, abamectin and pyrethroids (betacyflurin 50 and 125 g/l and esfenvalerate) insecticides reduced parasitism rates. T. pretiosum emerged from A. kuehniella eggs treated with esfenvalerate but were not able to parasitize non treated eggs of this host. B. thuringiensis, lufenuron and triflumuron may be used in integrated pest management programs to control tomato pests, because they have moderated negative effect on parasitoid wasps.

Triatoma brasiliensis Neiva is the most important vector of the Chagas' disease in the semiarid zones of North-eastern Brazil. Adult bugs have two main pairs of exocrine glands, the metasternal and the Brindley's glands, which release volatiles possibly with defense, alarm and/or mating functions. To date, anatomical and histological studies of the metasternal and the Brindley's glands in the genus Triatoma are scarce and, considering the relevance of these exocrine glands, the present work aimed at studying their morphology in T. brasiliensis. The metasternal and the Brindley's glands of T. brasiliensis consist of glandular units similar to those described for Rhodnius prolixus Stål and Panstrongylus megistus Burmeister, comprising a secretory apparatus, saccule and collector duct.

The three major pheromone components found in gland extracts of both rice and corn strain Spodoptera frugiperda virgin females were Z9-14:Ac, Z11-16:Ac and Z7-12:Ac, However, both the concentrations and relative proportions of the compounds varied significantly between strains as a function of female age and the time during the scotophase that the glands were extracted. The concentration of Z9-14:Ac found in the glands of hybrid females, coming from corn × rice and rice × corn crosses differed significantly, but in both cases did not differ significantly from that of maternal line females. The results suggest that synthesis is controlled, at least in part, by the W chromosome. Given the intraspecific variability reported in other species of Lepidoptera, both with respect to female pheromone production and male responsiveness, it would appear rather unlikely that these differences alone would be sufficient to ensure reproductive isolation of the two strains.

The effect of nine insecticides used in tomato production was evaluated on adults of two Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) populations from Rive and Afonso Cláudio, Espírito Santo State, Brazil. The experiment was developed in an acclimatized chamber at 25 ± 1°C, 70 ± 10% relative humidity and 14 h photophase. Eggs of Anagasta kuehniella (Lepidoptera: Pyralidae), previously immersed in insecticides solutions were offered to females of both T. pretiosum populations. Bacillus thuringiensis, lufenuron and triflumuron had lowest negative effects on parasitism and viability of individuals of these populations; however, abamectin and pyrethroids (betacyflurin 50 and 125 g/l and esfenvalerate) insecticides reduced parasitism rates. T. pretiosum emerged from A. kuehniella eggs treated with esfenvalerate but were not able to parasitize non treated eggs of this host. B. thuringiensis, lufenuron and triflumuron may be used in integrated pest management programs to control tomato pests, because they have moderated negative effect on parasitoid wasps.

The effect of the defense of the prey Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) on predation rates of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) females was studied. P. nigrispinus preyed 1.0, 1.4, 1.2, 3.8 and 3.0 and 0.4, 0.8, 1.6, 2.8 and 3.2 third instars of S. frugiperda larvae with and without defense, respectively, with the densities of one, two, four, six and eight larvae. The attack rate and the manipulation time were, respectively, 0.67 ± 0.39-h and 6.72 ± 2.88 h for P. nigrispinus females fed with larvae with defense and 2.51 ± 0.16-h and 0.51 ± 0.77 h for those without defense. The functional response of the predator P. nigrispinus varies with the defense and the density of the prey S. frugiperda, with larger consumption of prey without defense at higher densities.

We propose a shift in the traditional way to teach Entomology for undergraduate and postgraduate courses. We envisage a system in which undergraduate and postgraduate students interact, discussing Entomology outside the classroom. This would get them to actively seek for knowledge, rather than being paternalistically told how they should learn. Such a system does not preclude lectures as a didactic strategy, nor it rules out lecturers as responsible for instructorship. On the contrary, we believe lectures and discussion outside classroom are complementary for effective teaching. Our results show that undergraduate and postgraduate students who interact outside classroom are able to get better grades even when submitted to traditional written tests. Moreover, it seems that postgraduate students who get involved in such a system get permanent jobs faster than those postgraduates not taking part in it. Apparently, the key here was that when discussing outside classroom, students are allowed to think freely, rather than simply accumulating information taught in classroom. In doing so, they transform information into knowledge, and therefore, are able to solve even unforeseen problems.