Biological control of insect pests of strawberry (Fragariax ananassa Duch.) in Irapuato, Guanajuato, Mexico

Abstract

Strawberry is one of the main crops in the state of Guanajuato, Mexico. The main insect pests are: Tetranychus urticae (Koch.) , Trialeurodes vaporariorum (Westwood) and, Chaetosiphon fragaefolii (Cockerell) . In order to evaluate the impact of different natural enemies on these pests, two treatments were compared. The first treatment (T 1 ) consisted in pesticide application, the second treatment (T 2 ) was composed of the liberation of two natural enemies of these insect pests: Chrysoperla carnea (Stephens) and Hippodamia convergens (Guérin-Méneville). Coriander ( Coriandrumsativum L.) was planted on the side of the fields where the natural enemies were released. The adults of T. urticae were more abundant in T 1 than T 2 , by contrast,there were lower number of nymphs and adults of Ch. fragaefolii in T 1 ; nymphs and pupae of T. vaporariorum there were not significantly different between treatments. The populations of T. urticae and Ch. fragaefolii followed a similar pattern, appearing since the end of November and reaching a peak in April, whereas the population of T. vaporariorum showed three population peaks (December, February and June). The presence of C. carnea and H. covergens was similar between T. urticae and T. vaporariorum , but significant and different with respect of Ch. fragaefolii . The average number of T. urticae ’s eggs per leaf in the treatment with the release of natural enemies was of 130, compared with 1000 eggs/leaf in the conventional treatment. The population of whiteflies was lower in the biological control treatment. There was an effective pest control with the biocontrol treatment.