BACKGROUND: The immediate lethality caused by spinosad has been widely studied on Spodoptera exigua (Hübner). However, long‐term effects can also provide valuable information on insecticide toxic action. Here, the persistence of spinosad on Capsicum annuum L. foliage and the lethal and sublethal effects of greenhouse‐aged foliar residues of this insecticide on third instars of S. exigua are reported.RESULTS: Foliage was collected at 0, 3, 5, 10, 20, 30, 40 and 50 days after application, and spinosad residues were measured. Residues decreased over time according to first‐order kinetics. The average rate constant and half‐life of disappearance were 4.44 × 10⁻³ and 156 days and 5.80 × 10⁻³ and 120 days for 60 and 120 mg L⁻¹ respectively. Larval mortality gradually decreased, corresponding to the residues, but was still appreciable (35 and 65% for 60 and 120 mg L⁻¹ respectively) when the larvae were fed with foliage collected 50 days after treatment. Subsequently, pupal development was reduced and varied between 20 and 60% and between 21 and 41% for 60 and 120 mg L⁻¹, respectively, in all ages of leaf residues that were bioassayed. At all time points, the consumption rate by the larvae was reduced between 62 and 84% for both concentrations that were bioassayed.CONCLUSION: It is concluded that, under the present greenhouse conditions, the degradation of spinosad was slower than that reported by other authors in the field, and, because of that, its residues could cause lethal and sublethal effects to S. exigua larvae. Copyright © 2011 Society of Chemical Industry

The life cycle and several life parameters of the zoophytophagous predator Engytatus varians (Distant) (Heteroptera: Miridae), including nymphal growth according to Dyar’s rule, were examined in the laboratory. The egg, nymph (five instars), and adult stages were 9.20, 17.36, and 19.02 d in length, respectively. The growth ratio for nymphs was consistent with Dyar’s rule based on the lengths of the femora of the forelegs, the tibiae and femora of the middle legs, and the antennae. Some biological characteristics of E. varians were also evaluated when the mirid was fed three different diets (B. cockerelli third instars, Sitotroga cerealella Olivier [Lepidoptera: Gelechiidae] eggs, and a mixture of both instars and eggs). The length of the nymphal stage was three days longer on a diet of only S. cerealella eggs than when the mirids were fed the third instars of B. cockerelli only or a mixture of both. The sex ratio was not affected by the type of diet. Nymphs of E. varians consumed B. cockerelli nymphs (80–85) when fed third instars only and third instars + S. cerealella eggs, respectively. The potential use of this predator as a biological control agent of B. cockerelli is discussed.

The parasitism and host feeding behavior of Tamarixia triozae (Burks) (Hymenoptera: Eulophidae) females on Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) fourth instars that have infested tomato (Lycopersicon esculentum Miller) leaflets are described and quantified. Females took approximately 31.14 ± 4.39 min to search for their first suitable host. The recognition and handling times for oviposition were 2.66 ± 0.18 and 4.26 ± 0.39 min, respectively. T. triozae parasitized 4.66 ± 0.61 nymphs in a period of 6 h. The parasitoid explored and probed its host by walking along the margins of its body while antennating and repeatedly introducing the ovipositor beneath the nymph. The handling times before and during host feeding were 8.42 ± 0.67 and 8.29 ± 0.60 min, respectively. T. triozae females consumed 1.00 ± 0.00 B. cockerelli nymph after parasitizing 3.3 ± 0.48 nymphs. EPA–a refined soybean oil—imidacloprid, and abamectin caused between ∼70 and 100% T. triozae adult mortality after a 48-h contact treatment with fresh pesticide residue and a 47–91% decrease (abamectin > imidacloprid > EPA) in adult emergence when parasitized B. cockerelli fourth instars were directly sprayed. These data suggest that the use of these insecticides in combination with T. triozae in integrated pest management programs should be carefully evaluated.