Biology and fertility life table of Eriopis connexa, Harmonia axyridis and Olla v-nigrum (Coleoptera: Coccinellidae)

Life tables of the ladybird beetles Harmonia axyridis, Cycloneda sanguinea and Hippodamia convergens reared on the greenbug Schizaphis graminum

The Asian lady beetle Harmonia axyridis (Coleoptera: Coccinellidae) is a biological control agent that also may adversely impact other coccinellid species. Life table parameters were used to assess the population growth potential and the effects of interspecific competition between the invasive lady beetle H. axyridis and the native coccinellids Hippodamia convergens and Cycloneda sanguinea (Coleoptera: Coccinellidae) under laboratory conditions at 25 °C, using Schizaphis graminum (Hemiptera: Aphididae) as prey. The effects of the abiotic factors air temperature and humidity on these coccinellids by conducting a survey in a sorghum crop under average conditions of 18.1 °C and 53.5%, respectively, were also assessed. Fecundity was higher in C. sanguinea (1021.0 eggs per female) and H. axyridis (1029.2 eggs per female) than in H. convergens (484.5 eggs per female). The majority of the life table parameters showed no significant differences. The instantaneous rates of population increase (rm) of C. sanguinea, H. axyridis, and H. convergens were 0.195, 0.198, and 0.194 d-1, respectively. Based on the life table parameters obtained in this study, all three species of Coccinellidae showed a similar capacity to control a S. graminum population.

Suitability of spider mites and green peach aphids as prey for Eriopis connexa (Germar) (Coleoptera: Coccinellidae)

The ladybird Eriopis connexa is an important natural enemy of several pest arthropods in agroecosystems. High population of this predator is frequently observed in strawberry and soybean crops associated with spider mites. We used two-sex life table parameters to evaluate under laboratory conditions, the suitability of three species of spider mites (Tetranychus evansi, Tetranychus urticae, Tetranychus ogmophallos), and a species of aphid (Myzus persicae) as a prey for the predator E. connexa. Eriopis connexa completed immature development on all prey species except on T. evansi, in which all individuals of predator died before reaching the pupal stage. Among prey species that allowed the immature development of E. connexa, T. urticae and M. persicae provided a faster development time to the predator. Oviposition days, longevity and fecundity of E. connexa on T. urticae and M. persicae were substantially longer/higher than on T. ogmophallos. Net reproductive rate (R₀), intrinsic rate of increase (r), and finite rate of increase (λ) of E. connexa feeding on T. urticae and M. persicae were also higher than those on T. ogmophallos. Based on the overall performance of the ladybird, the order of suitability of prey species was M. persicae > T. urticae > T. ogmophallos > T. evansi.

Effect of Spatiotemporal Association and Trophic Interactions Between Aphidophagous Coccinellids Toward Aphid Control

Predator diversity in a system can have different results on the biological control of pests. Positive results can arise if natural enemies have niche complementarity, whereas negative effects can occur when one enemy interferes with heterospecifics-e.g., via intraguild predation-resulting in weaker pest suppression. Nevertheless, a coexistence is possible if enemies use the resource differentially leading to resource partitioning, and/or if the intraguild prey has some competitive advantage over the intraguild predator-i.e., is better at exploiting the shared resource or exhibits avoidance behavior. In this study, we conducted a series of field-sampling and semifield experiments to elucidate the spatiotemporal association patterns of the coccinellids Eriopis connexa (Germar) and Cycloneda sanguinea L. (Coleoptera: Coccinellidae) and determine how the trophic interactions between them could affect the biological control of aphids. We found that both coccinellid species coexist in sweet-pepper crops over time, and this coexistence could be explained by a temporal niche complementarity. Despite cooccurring spatially, they were segregated at the leaf level, which segregation can be explained by an avoidance behavior to prevent negative trophic interactions, such as cannibalism and intraguild predation. Under semifield conditions, the possible negative trophic interactions did not affect the control of aphids when both species were present, but the density of C. sanguinea was reduced at the end of the experiment. These results suggest that biological control strategies that include both species would be positive for the control of aphids on the basis of these considerations.

The way to maturity: taxonomic study on immatures of Southern Brazilian Coccinellini (Coleoptera: Coccinellidae) species important in biological control

Among the predatory ladybird beetles (Coccinellidae: Coleoptera), members of the Coccinellini, predators of aphids and psyllids, stand out. Although the beneficial status of these beetles has been acknowledged by biological control researchers, there are no keys or detailed studies on the immature stages of South American Coccinellidae, especially Coccinellini. We provide descriptions and illustrations of the immatures and adults of major predatory Coccinellini species in southern Brazil along with an identification key for fourth instar larvae and pupae. The following species are included: Cycloneda sanguinea (Linnaeus, 1763), Eriopis connexa (Germar, 1824), Harmonia axyridis (Pallas, 1773), Hippodamia convergens Guérin-Méneville, 1842 and Olla v-nigrum (Mulsant, 1866). The morphological study, which included the use of scanning electron microscopy, revealed new characters such as the type of tarsal claws, spiracles, chalazae, parascoli and strumae. The identification key provided here may be useful in biological control programs.

The Effect of Different Dietary Sugars on the Development and Fecundity of Harmonia axyridis

The aim of this study was to screen synergistic substances included in existing artificial feeds in order to improve the fertility and survival rate of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), an efficient pest predator. To this end, we analyzed the potential effects of glucose and trehalose on the growth, development, and reproduction of H. axyridis and evaluated the effect of three different artificial feeds on the energy stress of H. axyridis. The artificial diets contained fresh pork liver, honey, sucrose, vitamin C, and royal jelly, which was marked it as Diet1. The glucose was added to diet1, which was marked it as diet2, while adding trehalose to diet1 was marked as diet3. The pre-oviposition period of H. axyridis on Diet 1 was slower than that of Diet 2 and Diet 3. Additionally, the spawning quantity and incubation rate of insects on Diet 2 and Diet 3 were significantly higher than that of those on Diet 1. Finally, the larval developmental time on Diet 1 was significantly slower than that of Diet 2 and Diet 3. These results indicate that the addition of an appropriate amount of glucose or trehalose may affect positively the growth, development, and reproduction of H. axyridis. In addition, further studies showed that ATP, amino acids and fatty acids content in the H. axyridis also increased after the addition of the synergistic substance. All these results show that proper adjustment of stored energy anabolic and catabolism is important to maintain the metabolic balance of the insect’s entire life cycle and the addition of glucose or trehalose has a certain effect on the life indicators of H. axyridis.

Survival, development and reproduction of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on kaolin-treated cotton

The mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is a cotton pest widespread in several cotton growing regions of Brazil, particularly in the semi-arid region of southwestern Bahia. The impact of kaolin on survival, development and reproduction of P. solenopsis was evaluated in the laboratory. The experiment was developed in a completely randomized design with two treatments: immature or newly emerged adults of P. solenopsis sprayed with kaolin and fed with cotton leaf discs treated with kaolin suspension (with kaolin) (T1) and immature or newly emerged adults of P. solenopsis sprayed with distilled water and fed with cotton leaf discs treated with distilled water (without kaolin) (T2). The kaolin suspension shortens the life cycle, increases the reproductive potential and population growth of the cotton mealybug, P. solenopsis and, therefore, it should be used with caution on cotton plants in regions with a history of occurrence of this pest.

Alternative food sources for the ladybird Brumoides foudrasii (Mulsant) (Coleoptera: Coccinellidae)

The predator Brumoides foudrasii (Mulsant) (Coleoptera, Coccinellidae) has been naturally found in plants infested by mealybugs. In this study, the striped mealybug Ferrisia dasylirii (Cockerell) (Hemiptera, Pseudococcidae) and Anagasta kuehniella Zeller (Lepidoptera, Pyralidae) eggs were evaluated as diets for the development and reproduction of B. foudrasii. Brumoides foudrasii immatures developed faster when fed with A. kuehniella eggs than when fed with F. dasylirii. However, the survival and longevity of B. foudrasii adults were not affected by the diets. Oviposition was more frequent when B. foudrasii females were fed with F. dasylirii (95%) than those fed with A. kuehniella eggs (65%). Brumoides foudrasii females fed with F. dasylirii were 2.5 times more fecund than those fed with A. kuehniella eggs. Although both diets may be considered proper for B. foudrasii, A. kuehniella eggs were more suitable for immature development, while F. darsyrili provided more nutritious resources for adult biological parameters as oviposition period, egg viability and fecundity. These results suggests that this predator can play an important role in regulating populations of the stripped mealybug F. dasylirii in the field.