Biological development of Euborellia annulipes reared with artificial diets and Ephestia kuehniella eggs 1

related with production of natural enemies, nutritional requirements studies, production of sterile insects, pheromone and semiochemical tests, as well as educational purposes (Parra 2001). ABSTRACT Among the biological agents with appropriate characteristics to be inserted in integrated pest management programs, the Euborellia annulipes 1847 (Dermaptera: Carcinophoridae) species has a great due to its high capacity of preying large prey and of rearing it in the laboratory One of the forms of integrated pest management is the rearing of insects using artificial diets. The Euborellia annulipes species has gained prominence for being voracious with its preys, demonstrating a potential for use in biological control programs. This study aimed to evaluate the biological development of the E. annulipes predator fed with artificial diets and E. kuehniella eggs. Newly hatched predator nymphs were separated into an experimental unit consisting of 5 insects, 10 replicates and 7 treatments. The instars duration, nymphal period and viability, postures, number of eggs per posture, period of pre-oviposition and egg incubation and egg viability were evaluated. There was no difference for the periods nymphal, pre-oviposition and incubation of E. annulipes eggs. Oviposition ranged from 23.8 to 73.0 eggs/posture, as a function of diet. Artificial diets based on E. kuehniella eggs can be used for rearing E. annulipes . However, reared eggs fed with rice flour should be avoided, because they reduce oviposition and influence the E. annulipes development.


INTRODUCTION
The biological control of pests, in recent years, has been widely used in Brazil, with significant examples in integrated pest management (Pinto et al. 2005). One of the tools within integrated pest management is the possibility of insect rearing with artificial diets, with the same characteristics as those found in nature, aiming at studies related to plant resistance to insects, bioassays with insecticides, production of natural enemies, nutritional requirements studies, production of sterile insects, pheromone and semiochemical tests, as well as educational purposes (Parra 2001 One of the forms of integrated pest management is the rearing of insects using artificial diets. The Euborellia annulipes species has gained prominence for being voracious with its preys, demonstrating a potential for use in biological control programs. This study aimed to evaluate the biological development of the E. annulipes predator fed with artificial diets and E. kuehniella eggs. Newly hatched predator nymphs were separated into an experimental unit consisting of 5 insects, 10 replicates and 7 treatments. The instars duration, nymphal period and viability, postures, number of eggs per posture, period of preoviposition and egg incubation and egg viability were evaluated. There was no difference for the periods nymphal, pre-oviposition and incubation of E. annulipes eggs. Oviposition ranged from 23.8 to 73.0 eggs/posture, as a function of diet. Artificial diets based on E. kuehniella eggs can be used for rearing E. annulipes. However, reared eggs fed with rice flour should be avoided, because they reduce oviposition and influence the E. annulipes development.  (Silva et al. 2009b).

KEYWORDS
This predator constitutes a terrestrial group of insects of nocturnal habits, which are easily recognized by the presence of cornea tweezers at the extremity of the abdomen, which differentiates sexual dimorphism. They are known as "scissors" or "spiders" and hide, during the day, under very narrow cracks, under rocks and in humid places. At night, they are very active, moving with the tip of the abdomen facing upwards and the forceps very approximated. They are insects with chewing-type mouthparts and most of them feed on different types of prey (Guimarães et al. 1992, Gallo et al. 2002. Due to their diversified food habits, these predators present a high potential, being a possibility to use them in biological control programs, on different pests and in several crops, besides being possible to be used along with other control measures, encouraging the production of crops with less chemical residues and compatible with the purpose of integrated pest management (Silva et al. 2009b).
It is indispensable that studies related to its biology are developed. Thus, this research aimed at evaluating the biological development of Euborellia annulipes (Lucas) reared with artificial diets and Ephestia kuehniella Zeller eggs.
For the accomplishment of all the experimental tests, insects reared in laboratory were used. Nymphs and adults of E. annulipes were individualized in Petri dishes (9.0 cm in diameter x 1.5 cm in height), containing absorbent paper moistened daily and feed composed of a standard diet (5 g) used to feed the scissors (Lemos et al. 1997) and E. kuehniella eggs (0.02 g) from different diets ( Table 1). The diet was supplied in plastic containers of 5.5 cm in diameter and 0.5 cm in height, replenished every two days. At three-day intervals, plaque papers were exchanged to control the incidence of microorganisms. To evaluate the biological development of the predator, seven treatments, with ten replicates, composed of five insects of E. annulipes, were used.
Observations were made daily, quantifying the duration of the nymphal phase and the instar change, registered in intervals of days, between ecdysis (presence of exuviae in the breeding vessel), or by observing the coloration of the nymphs. In some cases, individuals may feed on their own exudation after ecdysis. The estimated biological parameters were duration and survival of the immature stages.
In the adult phase, 10 couples of each treatment were separated in Petri dishes and kept with the same methods used for nymphs (diet of each treatment and environmental conditions). After verifying the occurrence of postures, the males were removed from the plates and the females were kept together with their eggs. Daily evaluations were carried out, measuring the female reproductive capacity by counting deposited eggs, pre-oviposition period, egg incubation period and viability of eggs (hatched eggs).
The experimental design was completely randomized, in a factorial scheme, with 7 diets x 4 instars, with 10 replicates per treatment. Data were submitted to analysis of variance (Anova) and the means were compared by the Tukey test (p ≤ 0.05). The data obtained were analyzed by the statistical software SAS.9.1.3.

RESULTS AND DISCUSSION
It can be noted that, for the nymphal period of the E. annulipes scissors, there was no statistical difference among treatments, during the first, second and third instars. However, for the duration of the fourth instar, it was found that the treatment 3 had a significantly longer duration of nymphal status, if compared to the treatments 2, 5 and 6. The duration of the fourth instar nymph was greater than that of the rest in all treatments, except for the treatment 6, while the first and second instars were lower for the treatments 4 and 5 (Table 2).
No difference was observed for the nymphal period duration of E. annulipes, in relation to the diets tested, ranging from 41.2 to 50.6 days (Table 3). Silva et al. (2010a), considering Hemiptera: Aphididae from the first-second, third and fourth instars as preys, observed a nymphal period of 53.2, 59.5 and 63.2 days, respectively, and between 49.8 and 61.7 days, when fed with S. frugiperda eggs.
As for nymphal viability, the treatments 5 and 6, i.e., those fed with E. kuehniella eggs from rice flour, presented a survival rate of about 50 %, while all other treatments presented viability between 70 % and 80 %. There were significant differences between the treatments 2 and 7 (Table 3). The low survival of the nymphs fed with eggs of this Crambidae from diets 5 and 6 makes this food a restricted source for laboratory rearing.
The pre-oviposition period varied from 9.4 days, in the treatment 2, to 11.6 days, in the treatment 6 (Table 3), and there was no significant difference between the diets tested. However, for the number of eggs per posture, the treatment 5 had a lower number of eggs (23.8 eggs/posture), differing significantly from the treatments 1 and 6, with 71.6 and 73.0 eggs/ laying. Pinto et al. (2005), when testing E. kuehniella eggs for this predator, obtained an average of 52.1 eggs/posture, every three days. This indicates that the diet that is used in the mass rearing of the eggs that are supplied to the predators influence directly in the development of the adult phase and, consequently, in its oviposition.
The mean egg incubation period ranged from 9.6 (treatment 3) to 11.0 (treatment 2) days and did not differ significantly among treatments. Regarding egg viability, the treatment 5 presented * Means followed by the same letter, lowercase in the column and upper case in the row, do not differ from each other by the Tukey test at 5 % of probability.
* Means followed by the same letter do not differ by the Tukey test at 5 % of probability. a viability of 60 %, differing statistically from the treatments 1 and 7, with a viability greater than 95 % (Table 3). These results were close to the data found by Pinto et al. (2005), who observed an average incubation period of 8.2 days for E. annulipes on Anagasta Kueniella Zeller eggs. Similar results were found by Silva et al. (2009c), who observed a mean incubation period of 13.3 days for E. annulipes fed with S. frugiperda (Smith, 1797) (Lepidoptera: Noctuidae), with a viability of 94.5 %. This predator showed a mean incubation period of 12.9 days, when it was fed with Hyadaphis foeniculi Passerini (Hemiptera: Aphididae) (Silva et al. 2010a).
Studies conducted by Drankin et al. (1995) and Silva et al. (2010a) reported that, during the incubation period, E. annulipes females protect both the eggs and first instar nymphs after hatching, positioning themselves on or around them, and even moving the eggs with their jaws, rotating them by means of fast movements to the original position. This procedure is a form of asepsis or cleaning of the eggs to avoid the attack of fungi or mites, in its absence.

The development time and biological parameters
related to the reproduction of Euborellia annulipes may vary as a function of the Ephestia kuehniella feeding, whose eggs are used for the mass rearing of this Dermaptera; 2. E. kuehniella eggs originated from rearing with rice flour reduce the oviposition and negatively influence the biological development of E. annulipes.