Desenvolvimento e sobrevivência de Euborellia annulipes com dieta vegetal, animal e mista

Abstract

The Dermaptera order is composed by species considered generalist predators, much used in the biological control of several insect pests. The earwigs, Euborellia annulipes (Dermaptera: Anisolabididae) is an omnivorous species, considered an important controlling agent for larvae and pupae of boll weevil and other insect pests of economic importance. However, a few studies claim that this earwig is predominantly phytophagous, with the potential to become a secondary pest in protected crops. Therefore, the objective of this research was to determine the development and survival of E. annulipes with cotton leaves and/or cotton boll weevil larvae. The experiment was conducted at the Entomology Laboratory of the Embrapa Cotton, municipality of Campina Grande, Paraiba, Brazil. The experimental design was completely random, with three treatments and 50 replicates. The treatments consisted of nymphs of the earwigs fed with: (1) disc of cotton leaves and water (vegetable diet); (2) third instar larvae of boll weevil and water (animal diet) and (3) larvae of boll weevil, cotton leaf and water (mixed diet). The nymphs of the earwigs were fed 'ad libitum' with one of the three diets mentioned and kept in climatic chambers of type B.O.D. at 25 °C, relative humidity of the 60 ± 10% and 12 hours of the photoperiod until the end of the bioassay. Subsequently, adults of the earwigs were sexed, grouped into couples for copulation and after mating individualized in plastic pots and fed with the three types of diet mentioned and kept in a climatic chamber until death. The survival and duration of each instar and nymphal stage of E. annulipes were determined by recording the interval in days between ecdises, as well as sexual ratio, adult longevity and the following morphometric data: body length, number of antenomers and abdominal segments. The results obtained in this research indicate that only the consumption of vegetable diet by E. annulipes is not enough to meet the nutritional requirements of its immature stages. Nymphs of early stages of development prefer to feed on an animal diet, while the more advanced stages of development and adults prefer to feed on mixed diet, exhibiting zoophytophagous behavior. Nymphs of E. annulipes fed with mixed diet presented higher number of antenomers in the third, fourth and fifth instars, originating a larger number of females. Regardless of the diet consumed, fifth and sixth instars of E. annulipes were longer than the fourth instar adults.