Morforlogía y biología de Hyalochloria denticornis predator de los huevos de Anomis texana

Abstract

This paper deals with studies on Hyalochloria denticornis Tsai Yu-Hsiao (Miri-dae), conducted between July, 1958 and April, 1960 at La Molina Experiment Station, Lima, Peru. It presents: 1) descriptions of the different developmental stages and sexual dimorphism of adults; 2) the life history in winter and summer upon two different preys, adjusted to actual conditions observed in the fields: Aphis gossypii Glov. (winter prey) and Anomis texana Riley eggs (summer prey); 3) studies or the food regimen and predatory capacity upon Anomis eggs, 4) summary of observations on the influence of ecological factors such as temperatme and relative humidity, and 5) studies on the reproductive capacity Results obtained may be summed up as follows: 1) Sexes are easily distinguis-

bable because of the differentiated male antennae; this diferentiation being functional because the antennae are used by the male to hold the female at the beginning of the copulatory act, 2) the life history takes 30-45 days in winter and 20-29 days in sum-met, from egg to adult stage. Incubation lasts 10-7 (8-13 days in winter and 8.5 (6-13) days in summer Adults live up to 47 (females) and 53 (males) in winter or 32 (females) and 36 (males) days in summer, averaging 247 and 17.0 days in winter and summer respectively, disregarding sexes. Nymphs develop in 27 4 (24-32) days in winter and in 14.55 (13-16) days in summer. mev. All data are referred to room temperature of 19°C (winter) and 27°C (summer), 3) first instar nymphs never prey unless they are in their fourth day of life (usually a four day old nymph is in the second stage). After the first molt (three days) a mixed diet starts, predation upon Anomis eggs averaging 0.89 eggs daily, if account is taken of the first three days or 1.03 if these days are disregarded Adult females devom an average of 4.64 eggs daily against an average of only 1.9 in the case of males. A single female, long lived (32 days) devoured 169 eggs (average of 5 28 eggs every day). As this insect is often found in numbers of 30 or more per group of plants (two or three stalks in each group), even up to 80 (April 1959), it is no wonder that it is such an important enemy of Anomis texana The food regimen is of a mixed diet, usual preys are Aphis gossypii in winter and Anomis eggs in summer. The cotton leaf plays an important sole, as it was shown statistically The use of the cotton plant as food plant explains the marked susceptibility of Hyalochloria to some systemic insecticides. Apparently Hyalochloria is partially restricted to the cotton plant for food and for reproduction. This dependence on the cotton plant for food together with its preference for the lower surface of leaves located in the low and middle part of the plants, the same being chosen by Anomis females for oviposition, accounts for the near specificity in predation. 4) This insect does not seem to be influenced in its chronological distribution by factors such as temperature and relative humidity as existing in the central coast of Peru, but rather by the seasonal cutting (vatooting) or destruction of cotton plants due to dependence on this plant. Most certainly, as the author had observed in 1958-59, suppression of ratooning reduces this insect almost to extinction or to a level of population where it no longer plays any important role as an enemy of Anomis texana. 5) Data on the reproductive capacity of Hyalochloria as shown by unmated females under laboratory conditions are also included. Although all females under observation were reared with males for all or part of their lives no copulation occurred for unknown reasons, the eggs being consequently sterile. The maximum number of eggs laid by one female was 209, laid through an oviposition period of 33 days (length of life 47 days) This was an exceptional record, for several other females living as long or longer, and laying eggs for a longer time (from 35 to 48 days), laid only from 74 to 123 eggs. With females surviving less than twenty days, oviposition drops to less than 20 days depending partially upon the length of their lives No oviposition occurs unless females feed upon lepidopterous eggs, the length of the preoviposition period depends upon when such food is available. Accordingly, seventeen females fed with Aphis gossypii Glov as prey laid no eggs. All of the life stages of this mirid bave been found only in cotton and Sida panniculata (Malvaceae) although adults have been found often on bean and potato plants.