New records of natural enemies of Plutella xylostella (L.) (Lepidoptera: Plutellidae) in Pernambuco, Brazil

Abstract

-We report the occurrence of natural enemies of Plutella xylostela (L.) in organically farmed kale in Pernambuco, Brazil. Seven natural enemies were observed parasitizing or preying on larvae and pupae of P. xylostella -three parasitoids: Cotesia plutellae Kurdjumov (Hym.: Braconidae), Conura pseudofulvovariegata (Becker) (Hym.: Chalcididae) and Tetrastichus howardi (Olliff) (Hym.: Eulophidae), and four predators: Cheiracanthium inclusum (Hentz) (Araneae: Miturgidae), Pheidole sp.Westwood (Hym.: Formicidae), nymphs and adults of Podisus nigrispinus (Dallas) (Hem.: Pentatomidae), and one unidentified species of solitary wasp. Beyond recording these natural enemies, data on predation of P. xylostella larvae in the field and laboratory by C. inclusum are presented.KEY WORDS: Natural biological control, Cotesia, Conura, Tetrastichus, Cheiracanthium, Podisus, PheidoleThe diamondback moth (DBM), Plutella xylostella (L.), is the most destructive pest of crucifers worldwide. The estimated average control cost for DBM is greater than one billion dollars per year (Talekar 1992, Haseeb et al 2004. Intensive insecticide use continues to be the primary method of control against P. xylostella (Barros et al 1993, França & Medeiros 1998, Cheng et al 2008. As a result of biological and behavioral traits of DBM (e.g., great ability to disperse, high fecundity and short life cycle) and conditions offered by the environmental sites (e.g., availability of various crucifers in neighbor fields and throughout the year), P. xylostella has been considered as difficult to control. Thus, use of biological control methods is important for the management of this pest, and augmentation of biological control agents already present is prominent because it has minimum or no cost to growers.In this work we report natural enemies of P. xylostella on an organic farm of kale crop (~90 days old) located in Chã Grande, Pernambuco State, Brazil (08 o 15'14.4''S and 35 o 30'0.3''W with an altitude of 505 m). To sample the natural enemies we exposed sentinel 3 rd -instar DBM larvae at the rate of 30 larvae per kale plant in the field. The exposure system consisted of 15 plants distributed along two transects marked in the study area. Selected plants were eight meters apart and distributed throughout the kale field. Eight out of 15 plants monitored were confined using cylindrical cages (50 cm diameter x 80 cm high) made with 4 mm mesh nylon fastened with wood sticks. Three days after infestation, all remaining DBM larvae were collected, and held for rearing until either an adult DBM or a parasitoid emerged. Predators observed directly preying on larvae or pupae in the field were noted.Because there were significantly fewer P. xylostella larvae recovered in the uncaged plants, and the caged plants excluded spiders and predatory wasps, a study was conducted in the field and in the laboratory to measure the predation rates of the spider species on DBM larvae. The spider species found preying upon DBM larvae in the field was identified as Cheiracanth...

Relationship between predation byPodisus nigrispinusand developmental phase and density of its prey,Plutella xylostella

“…Predators often consume leaf material when they have only access to pupae of P. xylostella , which is the least preferred prey. Recent studies have also shown that P. nigrispinus individuals can ingest the contents of phloem and intercellular spaces of plants (Silva‐Torres et al., ).…”

Interactions of Bacillus thuringiensis bioinsecticides and the predatory stink bug Podisus nigrispinus to control Plutella xylostella

“…Westwood (Hymenoptera: Formicidae) and the nymphs and adults of Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae) (Silva‐Torres et al. ).…”

“…Hence, the use of the predator P. nigrispinus , which occurs naturally in brassicas (Silva‐Torres et al. ), together with microbial control seems to be an ideal approach to address the problem of pest developing resistance and attacking the remaining survivors in treated field populations (Johnson et al. ).…”

Comparison of Eggs, Larvae, and Pupae ofPlutella xylostella(Lepidoptera: Plutellidae) as Prey forPodisus nigrispinus(Hemiptera: Pentatomidae)

“…2008, cotton (Medeiros et al 2000), eucalyptus (Torres et al 2006), ' Corresponding author, e-mail: amvacarl@gmail.com. tomato (Vivan et al 2002), and crucifers (Brassicaceae; Silva- Torres et al 2010).…”