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.

The life cycle of Neotropical ground beetle, Abaris basistriata (Coleoptera: Carabidae) reared on different substrates / Ciclo de vida do besouro de solo Neotropical, Abaris basistriata (Coleoptera: Carabidae) criado em diferentes substratos

Abstract Carabids are recognized worldwide as biological control agents of agricultural pests. The objective was to compare the life cycle of Abaris basistriata Chaudoir (Coleoptera: Carabidae) on three substrates: soil, fine vermiculite, or paper napkins. The biological cycle of A. basistriata presented different durations in soil and paper. The viability of eggs and larvae survival of the first and second instars were similar on all three substrates, while the third instar and pupa in the soil presented higher survival when compared with vermiculite and paper. The soil substrate was more favorable for the longevity of the carabid beetle. Abaris basistriata showed a shorter pre-oviposition period and a higher oviposition and post-oviposition period in the soil. Fecundity and fertility were higher when A. basistriata was reared on soil. The soil was most favorable substrate for rearing of A. basistriata in the laboratory. This information may make this species useful for the biological control.

Resumo Os carabídeos são reconhecidos mundialmente como agentes de controle biológico de pragas agrícolas. O objetivo foi comparar o ciclo de vida de Abaris basistriata Chaudoir (Coleoptera: Carabidae) em três substratos: solo, vermiculita fina, ou guardanapos de papel. O ciclo biológico de A. basistriata apresentou diferentes durações no solo e no papel. A viabilidade dos ovos e a sobrevivência das larvas do primeiro e segundo instares foram semelhantes nos três substratos, enquanto que o terceiro instar e a pupa apresentaram maior sobrevivência no solo quando comparados com vermiculita e papel. O substrato solo foi mais favorável à longevidade do carabídeo. Abaris basistriata mostrou menor período de pré-oviposição e maior período de oviposição e pós-oviposição no solo. A fecundidade e a fertilidade foram maiores quando A. basistriata foi criado no solo. O solo foi o substrato mais favorável para a criação de A. basistriata no laboratório. Estas informações são importantes e podem tornar essa espécie útil para o controlo biológico.

The life cycle of Neotropical ground beetle, Abaris basistriata (Coleoptera: Carabidae) reared on different substrates.

Carabids are recognized worldwide as biological control agents of agricultural pests. The objective was to compare the life cycle of Abaris basistriata Chaudoir (Coleoptera: Carabidae) on three substrates: soil, fine vermiculite, or paper napkins. The biological cycle of A. basistriata presented different durations in soil and paper. The viability of eggs and larvae survival of the first and second instars were similar on all three substrates, while the third instar and pupa in the soil presented higher survival when compared with vermiculite and paper. The soil substrate was more favorable for the longevity of the carabid beetle. Abaris basistriata showed a shorter pre-oviposition period and a higher oviposition and post-oviposition period in the soil. Fecundity and fertility were higher when A. basistriata was reared on soil. The soil was most favorable substrate for rearing of A. basistriata in the laboratory. This information may make this species useful for the biological control.

Interactions between the entomopathogenic fungi Beauveria bassiana (Ascomycota: Hypocreales) and the aphid parasitoid Diaeretiella rapae (Hymenoptera: Braconidae) on Myzus persicae (Hemiptera: Aphididae).

The interactions between the entomopathogenic fungus Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Ascomycota: Hypocreales) and the aphid parasitoid Diaeretiella rapae McIntoch (Hymenoptera: Braconidae) were evaluated under laboratory conditions. Nymphs of Myzus persicae Sulzer (Hemiptera: Aphididae) were first exposed to parasitoid females for 24 h and then 0, 24, and 48 h afterwards sprayed with a solution of B. bassiana. Likewise, aphids were also sprayed with B. bassiana and then exposed to parasitoids at 0, 24, and 48 h afterwards. Parasitism rate varied from 13 to 66.5%, and were significantly lower in treatments where the two agents were exposed within a 0-24 h time interval compared with the control (without B. bassiana). Parasitoid emergence was negatively affected in treatments with B. bassiana spraying and subsequent exposure to D. rapae. Decreases in longevity of adult females of the D. rapae F1 generation were observed in treatments with B. bassiana spraying. The application of these two biological control agents can be used in combination on the control of M. persicae, wherein this use requires effective time management to avoid antagonistic interactions.

Effect of Low-Temperature Storage on Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae).

We evaluated the effects of constant low-temperature storage on Diaeretiella rapae (McIntosh) (Braconidae, Aphidiinae). Diaeretiella rapae mummies were stored at 5 ± 1°C for 0-36 days. The percentage of D. rapae emergence varied (100-83%) after 0-32 days of storage. After 32 days, emergence reduced to 55%. According to our Probit analysis, 50% mortality (LT50) of the population of D. rapae was reached after 40 days of storage at 5°C. Storage for up to 32 days did not negatively affect emergence and survival. Cold exposure of D. rapae for 36 days did not influence morphological malformations, sex ratio, and emergence of the F1 generation. After 4-36 days of storage, D. rapae showed a gradual decrease in emergence, longevity, reproductive capacity, and F1 sex ratio. Diaeretiella rapae can be stored for up to 24 days at 5°C, at which time the percentage of parasitism and the F1 sex ratio remain above 38% and at 0.50, respectively.

Host quality of different aphid species for rearing Diaeretiella rapae (McIntosh) (Hymenoptera: Braconidae).

This study aimed to evaluate the quality of the aphid Myzus persicae (Sulzer), Lipaphis erysimi (Kaltenbach) and Brevicoryne brassicae (L.) as hosts for the parasitoid Diaeretiella rapae (McIntosh). Parasitization by D. rapae was higher on M. persicae than on L. erysimi and B. brassicae. The time of development of D. rapae from egg to mummy or egg to adult male or female were shorter on M. persicae than on L. erysimi and B. brassicae. Moreover, D. rapae showed no significant differences in the emergence rate, sex ratio and longevity when reared on the three aphid species. Myzus persicae was the largest aphid host, with B. brassicae and L. erysimi being of intermediate and of small size, respectively. Diaeretiella rapae reared on M. persicae was larger than when reared on L. erysimi and B. brassicae, and females of D. rapae were significantly larger than males on M. persicae, but males of D. rapae were larger than females when reared on L. erysimi. No difference in size was detected between males and females in parasitoids reared on B. brassicae. Among the aphid species studied, M. persicae was found to be the most suitable to D. rapae.

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% 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%, while the rate was 50.0% and 23.4% 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.