The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a widespread pest species of various cultivated plants. The pest status of FAW in cotton in the Cerrado region of Brazil has increased with the recent changes in cotton crop systems, such as double cropping and the use of cover or winter crops with non‐tillage cropping systems. In this study we investigated the performance of FAW on three major crops cultivated in the Cerrado – soybean, corn, and cotton – and millet which has been integrated into the landscape as a cover crop. Further, the damage to various reproductive structures of cotton plants by FAW larvae was determined. Both studies were conducted under field conditions. Survival of FAW larvae caged on millet plants was higher than on other hosts. The FAW reared on millet also exhibited a net reproductive rate similar to that observed on corn, which was considered the best host for FAW, and the highest intrinsic rate of increase and lowest mean generation time compared to all other hosts. In cotton, the low availability of bolls during the plant’s blooming stage resulted in higher square feeding, whereas infestation during the plant’s boll stage resulted in higher loss of bolls and lower attack on squares. The number of adults produced in a generation was higher when plants were infested in the boll stage. The results indicated that FAW is a threat to cotton when bolls are available and can cause significant loss of reproductive structures. In addition, based on the FAW performance feeding on millet, this cover crop can be among the reasons of FAW increasing pest status in subsequent crops.

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The coccinellid Tenuisvalvae notata (Mulsant) (Coleoptera: Coccinellidae) has been observed recently in association with the striped mealybug Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae) and the false cochineal scale Dactylopius opuntiae Cockerell (Hemiptera: Dactylopiidae) in the semiarid region of Pernambuco, Brazil. The latter species are important pests of cotton and prickly pear, respectively. In this study, we tested the two scale insects as prey for T. notata. In addition, eggs of Anagasta kuehniella Zeller (Lepidoptera: Pyralidae) were tested as possible alternative prey for rearing T. notata. In this work, the survivorship, reproduction, and predation of T. notata were investigated. The coccinellid T. notata was able to complete development only on F. virgata with 83% larval and pupal viability. Females of T. notata fed F. virgata produced 7.6 eggs a day with an eclosion rate of 61.9%. No oviposition occurred while feeding on A. kuehniella eggs. The highest consumption rate of F. virgata occurred during the last larval instar. Our results support the use of T. notata as an agent for the biological control of F. virgata, a highly polyphagous pest worldwide.

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ABSTRACT. Population growth and within-plant distribution of the striped mealybug Ferrisia virgata (Cockerell) (Hemiptera, Pseudococcidae) on cotton. The striped mealybug, Ferrisia virgata (Cockerell) (Hemiptera, Pseudococcidae), is a widely distributed and polyphagous pest species, which naturally occurs on cotton plants in Brazil. This study evaluated the establishment and population growth as well as the within-plant distribution of F. virgata on four cotton cultivars: CNPA 7H (white fibers), BRS Verde, BRS Safira, and BRS Rubi (colored fibers). The experiment was conducted in a complete randomized design with four treatments (cultivars) and 18 replications of each. Thus, cotton plants of each cultivar were infested with 100 newly hatched nymphs of F. virgata. The number of adult female mealybugs and the total number of mealybugs per plant were quantified, respectively, at 25 and 50 days after infestation. The developmental and pre-reproductive periods were also determined. Furthermore, we verified the distribution of F. virgata on the plant parts at 25 and 50 days after infestation. Ferrisia virgata showed similar growth of 412-fold in the four cotton cultivars studied. Also, the nymphs were spread on infested leaves; the secondgeneration nymphs were spread and established in all plant parts. Our results characterize F. virgata as having much potential as an important cotton pest in Brazil.

Mealybugs have strong associations with their host plants due to their limitations for dispersal. Thus, environmental conditions and host quality may impact the biological traits of mealybugs. To the best of our knowledge, we are the first to report on the biology of a Brazilian population of the striped mealybug Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae), which has recently been reported to infest cotton in Brazil. We evaluated the development and reproductive performance of F. virgata reared under different temperatures (25, 27, and 28°C) and mating status. The type of reproduction was also studied with insects reared on a factitious host and on cotton plants. Shorter development was obtained at 28°C as follows: nymphs generating males and females exhibited three and four instars with a mean duration of 19.1 and 20.5 days, respectively. The nymphal viability ranged from 77 to 96%, and was highest at 25°C. Females reared at 28°C initiated reproduction earlier (16.4 days), but the reproductive period was similar in all temperatures (∼16.2 days). Females produced more nymphs at 27 and 28°C (440 and 292 neonates) than at 25°C (277 neonates), although they lived longer at 25°C (63 days). Ferrisia virgata females exhibited only sexual reproduction. Thus, only mated females produced offspring, whereas unmated females died without reproducing. Therefore, the studied population of F. virgata exhibited only sexual reproduction with high survival and offspring production when fed cotton. Furthermore, pumpkin is a feasible host for mass rearing this mealybug species in the laboratory, an opening avenue for future studies.

Sap-sucking sessile insects depend on their selected host plant for their development; hence, they are influenced by the nutritional quality of the plant, especially the available nitrogen (N) and water content in the plants. The levels of N in the plant sap can vary as function of the N fertilization applied to enhance crop yield, while deficit of water takes place during drought periods. The performance of the striped mealybug on cotton plants subjected to N fertilization and water stress (=deficit of water) was evaluated. Potted cotton plants grown in a greenhouse were subjected to N fertilization and two irrigation regimes considering regular irrigation and water stress. Cotton plants were infested with 150 newly hatched nymphs. The survival was measured as the percentage of mealybugs alive 25 days after infestation. The biological traits of duration of development ? the pre-reproductive period, and the number and sex ratio of the offspring were determined. The survival of nymphs was similar across all treatments and averaged 38 %. Likewise, the developmental times were similar across treatments averaging 47 days, with 84 % of female offspring. However, offspring production was nearly twofold higher for waterstressed plants with successive N fertilizations. Offspring production was increased by 37 % as a function of water stress, and by 18 % as a function of N fertilization. Therefore, we conclude that the striped mealybug performance is enhanced on cotton plants under N fertilization and water stress. Based on the results, proper fertilization and irrigation management relieving plant from stress can be helpful in avoiding generalized infestations of striped mealybug on cotton.