Morphological characterization of pollens from three Apiaceae species and their ingestion by twelve-spotted lady beetle (Coleoptera: Coccinellidae) / Caracterização morfológica de três espécies de Apiaceae e sua ingestão pela joaninha de doze pintas (Coleoptera: Coccinellidae)

Abstract Larvae and adults of certain species of predator lady beetles feed on pollen, guaranteeing their survival, and at times, reproduction in the absence of preferred prey. Palynology, therefore, may contribute in the investigation of botanical families visited by these predators in order to obtain this floral resource. There are records of the visitation of Apiaceae flowers by Coleomegilla maculata DeGeer, 1775 (Coleoptera, Coccinellidae), but not the ingestion of their pollen grains by this lady beetle. The external morphology of pollen grains of three Apiaceae aromatic species (Anethum graveolens L., Coriandrum sativum L., Foeniculum vulgare Mill.) was characterized, and it was evaluated the ingestion of these pollens by fourth instar larvae and adults of C. maculata upon confinement along with flowers of these Apiaceae for 24 and 48 hours. The pollen grains of those species presented similar external morphology. In the two times of exposure, the larvae ingested the same amount of pollen from the three Apiaceae species, and the amount of C. sativum pollen ingested was the same between larvae and adults. The amount of A. graveolens pollen grains ingested by the adults was significantly greater than the pollens of C. sativum and F. vulgare, in 24 hours, with the opposite occurring in 48 hours. In the first 24 hours, the adults ingested more A. graveolens pollen than the larvae, with the opposite occurring with F. vulgare. There was no significant difference in the amount of Apiaceae pollen ingested between larvae and adults in 48 hours. The results suggest that the pollen-eating habits of certain aphidophagous lady beetles may be crucial in their preservation within agro-ecosystems.

Resumo Larvas e adultos de certas espécies de joaninhas predadoras podem se alimentar de pólen, garantindo a sua sobrevivência, e, às vezes, a reprodução na ausência da presa preferencial. Palinologia, portanto, pode contribuir na investigação de famílias botânicas visitadas por estes predadores a fim de obter esse recurso floral. Há registros da visitação de flores de Apiaceae por Coleomegilla maculata DeGeer, 1775 (Coleoptera, Coccinellidae), mas não da ingestão de seus grãos de pólen por essa joaninha. A morfologia externa de grãos de pólen de três espécies aromáticas de Apiaceae (Anethum graveolens L., Coriandrum sativum L., Foeniculum vulgare Mill.) foi caracterizada e avaliou-se a ingestão desses polens por larvas de quarto instar e adultos de C. maculata em confinamento com flores dessas Apiaceae por 24 e 48 horas. Os grãos de pólen dessas espécies apresentaram morfologia externa semelhante. Nos dois tempos de exposição, as larvas ingeriram a mesma quantidade de pólen das três espécies de Apiaceae, e a quantidade de pólen de C. sativum ingerida foi semelhante entre as larvas e adultos. A quantidade de grãos de pólen de A. graveolens ingerida pelos adultos foi significativamente maior do que a dos polens de C. sativum e F. vulgare, em 24 horas, com o oposto ocorrendo em 48 horas. Nas primeiras 24 horas, os adultos ingeriram mais pólen de A. graveolens do que as larvas, ocorrendo o oposto com F. vulgare. Não houve diferença significativa na quantidade de pólen de Apiaceae ingerida entre as larvas e adultos em 48 horas. Os resultados sugerem que o hábito de alimentar de pólen de certas joaninhas afidófagas pode ser crucial para a sua preservação dentro dos agroecossistemas.

Effects of Food Deprivation on the Development of Coleomegilla maculata (De Geer) (Coleoptera: Coccinellidae)

The lady beetle Coleomegilla maculata (De Geer) is a natural enemy of several insect pests and feeds on pollen and nectar to survive periods when prey is scarce. The effect of the feeding interval on the development, survival, fecundity, and longevity of C. maculata was determined. Newly hatched larvae of C. maculata were reared individually and fed with eggs of the Mediterranean flour moth Anagasta kuehniella (Zeller) at intervals of one, two, and three days under controlled conditions (23 ± 1ºC; 60 ± 10 percent RH; 12 h phtophase). The duration of larval instars and the total larval stage was prolonged as the feeding interval increased. The larval period lasted on average 9.2 ± 0.19 days when the larvae were fed daily with prey, and 14.6 ± 0.48 days when food was offered at three-day intervals. There was an inverse relationship between food intervals, survival, and weight of larvae and adults of the coccinellid. Survival rate of larvae fed daily was 76.8 percent, while the rate was 50.0 percent and 23.4 percent for larvae fed every two and three days, respectively. Coleomegilla maculata showed fecundity of 781.1 ± 149.02, 563.4 ± 80.81 and 109.0 ± 103.0 eggs when fed daily and at intervals of two and three days, respectively.

Evaluation of hot saline solution and restriction endonuclease techniques in cytogenetic studies of Cycloneda sanguinea L. (Coccinellidae)

The goal of the present study was to determine if simple methods, especially hot saline solution (HSS) and MspI and HaeIII restriction endonucleases, which do not require special equipments, may be helpful in studies of genetic variability in the lady beetle, Cycloneda sanguinea. The HSS method extracted the heterochromatin region, suggesting that it is composed mostly of DNA rich in A-T base pairs. However, the X and y chromosomes were resistant to HSS banding. These bands facilitated the identification of each chromosome. In this study, we used the restriction endonucleases with different G-C base target sequences: MspI C/GGC and HaeIII GG/CC. The use of restriction enzyme MspI did not show an effect on the autosomal chromosomes. On the other hand, the sex pair showed a pale staining, to help in the recognition of these chromosomes. HaeIII produced characteristic bands which were identified all along the chromosomes, facilitating the identification of each chromosome. Based on these results, we can consider the heterochromatin being heterogeneous. The findings obtained here, using different chromosomal banding techniques, may be useful in the identification of intraspecific chomosome variability, specifically in Coccinellidae (Coleoptera) chromosomes, even without special equipment.

Population dynamics of animals in unpredictably-changing tropical environments.

We studied population dynamics of a solitary phytophagous beetle, Epilachna viqintioctopunctata and a social stingless bee, Trigona minangkabau, in Sumatra, Indonesia for 5 years from 1981. Population increase of Epilachna vigintioctopunctata was suppressed in months of normal rainfall (≥300mm) but was released in the 1982-1983 El Nino-Southern. Oscillation when rainfall dropped to 50% of the long-term average. Mechanisms might be direct; rainfall lowered egg hatchability and the time of adult's residence on host plants. When dry weather continued for more than three generations, the Epilachna vigintioctopunctata population reached a density at which food shortage due to defoliation occurred. Although parasitism of immature stages was high, it was not a populationregulating factor. Thus, there were two types of ecological crunch: competition for food resources at the end of favourable dry periods and high mortality during heavy rainfall periods that usually followed El Nino-Southern Oscillation dry conditions. By an experimental addition of artificial nest sites, colony density of Trigona minangkabau increased 2·5 times the original density of natural colonies. One-half of artificial nest sites were occupied by arboreal ants and thus competition for nest sites with ants suppressed further increase of Trigona minangkabau. Intermediate rainfall was favourable for Trigona minangkabau because the rate of colony foundation decreased both during dry El Nino-Southern Oscillation months and months with heavy rain. Colony death was independent from rainfall. Many colonies that survived for 6 months persisted for >2 years and colony density was quite stable. Trigona minangkabau colonies could survive even under unfavourable periods, by hoarding resources in the nest. There was no significant ecological crunch during the study period and colony density almost always tracked the carrying capacity of the habitat, which was basically determined by nest-site abundance. Climatic conditions, especially rainfall, changed with various periodicities, 4-5 years for El Nino-Southern Oscillation, and 2 years for the monsoon and other shorter periods. The contribution of periodicities of 1 and 0·5 years, that were linked to movement of the sun, were weak, indicating that animals could not use seasonal changes of environments, e.g. daylength, to predict environmental changes. We discuss traits adaptive to such unpredictably-changing tropical environments. Separation of predictability of temporal environmental change and synchronous changes among patches improves our understanding. Low oviposition rate and resulting prolonged life-span of Epilachna vigintioctopunctata, usually associated with K-selected traits of life history, seem to be adaptations for unpredictable environmental changes.