Search

The leafroller Argyrotaenia montezumae (Walsingham) (Lepidoptera: Tortricidae) was found feeding on blackberry leaves ( Rubus sp.) in three localities of Michoacan, Mexico, for the first time in 2008. Several biological parameters of this insect were assessed under laboratory conditions (25 ± 2°C, 75 ± 5% relative humidity, and a photoperiod of 16:8 [L:D] h). The egg, larval (five instars), prepupal, pupal, and adult stages lasted 7.28, 21.62, 3.89, 8.37, and 17.64 d, respectively. Larval growth of A. montezumae followed Dyar's rule, and the growth ratios for the widths between the genae and the distance between the frontal setae of the head were 1.43 and 1.54, respectively. Female and male pupae weighed 33 and 21 ± 0.56 mg, respectively. The adult sex ratio (percentage of females) was 48%. When females oviposited on the inner walls of a transparent plastic container, the cumulative number of eggs per female over a lifetime was 391, with preoviposition and oviposition periods of 3.5 and 8.1 d, respectively. Peak oviposition activity was recorded when female age ranged from 4 to 8 d (47.35 and 52.12 eggs per female, respectively). The egg hatching percentage was 92.24%. The influence of the oviposition substrate color on the fecundity of A. montezumae was assessed using high-density polyethylene of different colors. The overall number of eggs per female was higher on green (352.5), blue (327.86), and yellow (250.60) substrates than on transparent (192.22) and pink (197.00) substrates.

Lepidopteran erebid Zale phaeograpta (Hampson) has recently been found feeding on blackberry leaves (Rubus sp., cultivar “Tupi”) in two sites of Michoacan, Mexico. The life cycle and several life parameters of this insect, including parasitism, were examined in the laboratory. The egg, larva (seven instars), prepupa, pupa, and adult stages lasted 4.1, 35.9, 3.1, 14.5, and 29.1 d, respectively. Eggs are turquoise blue. The prolegs of first-instar larvae have an enlarged dark area that runs laterally. From second instar onwards, a whitish longitudinal dorsal band is observed along the entire body. Third-instar larvae wear a pair of dorsal protuberances in abdominal segment VIII. The fourth- and fifth-instar larvae are cream-colored, whereas sixth instars are entirely creamy. Pupa is covered with a waxy bloom. The apical margin of the forewings in males has two silvery bands, whereas in females, a dark band is present. Female and male pupae had the same weight (0.5 g) and measured 2.21 and 2.25 cm, respectively. The adult sex ratio of females to males was 1.1:1. The cumulative number of eggs laid by female during her lifetime was 281, with preoviposition and oviposition periods of 9.9 and 7.3 d, respectively. Maximum oviposition occurred 3.9 d after the start of oviposition (87.7 eggs per female). Larvae of Z. phaeograpta were parasitized by Microplitis sp. (Braconidae) (33%) and a currently unidentified Ichneumonidae species (9%), and pupae were parasitized by Brachymeria comitator (Walker) and another unidentified Brachymeria sp. (Chalcididae).

The toxicity and sublethal effects of methoxyfenozide were evaluated in third instars of the beet armyworm, Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae), that fed on contaminated semisynthetic diet. The LC50 value was estimated at 0.23 mg of active ingredient (AI)/kg diet (range, 95% CI: 0.17–0.37) at 264 h after treatment. The effects on development, survival, and reproduction were observed in third instars of this pest that survived exposure to an LC25 concentration of methoxyfenozide. The larvae from the insecticide treatment exhibited lower pupal weights, an increase in both larval and pupal developmental times and a higher frequency of malformations of the wings in adults than untreated larvae. Adults from the methoxyfenozide treatment did not show reduced fecundity (mean cumulative number of eggs laid per female), but fertility as measured by the percentage of eggs hatched (fertility) was significantly reduced compared with untreated control insects. No significant effects were observed on pupal sex ratio. We concluded that the lethal and sublethal effects of methoxyfenozide are likely to have a significant impact on S. exigua populations on treated crops.