Tetrastichus howardi(Hymenoptera: Eulophidae) in Different Densities and Periods of Parasitism onDiatraea saccharalis(Lepidoptera: Crambidae) Caterpillars

Abstract

It is important to determine the suitability of parasitoid density and the parasitism period to obtain the desired number and quality of parasitoid offspring. The aim of this study was to establish the parasitism, emergence, number of progeny, duration of the life cycle (egg to adult), and sex ratio of Tetrastichus howardi (Olliff) (Hymenoptera: Eulophidae) with two parasitoid densities and eight parasitism periods on third-instar Diatraea saccharalis (F.) (Lepidoptera: Crambidae) caterpillars. Each caterpillar of this host was exposed to one or three T. howardi females for different periods of time (0.016, 0.5, 1, 12, 24, 48, 72, and 96 h) in plastic glass (100 ml). The parasitized hosts were transferred to glass tubes (8.5 cm in height by 2.5 cm in diameter) with an artiÞcial diet and were placed in a climatic chamber at 25 Ϯ 2ЊC, 70 Ϯ 10% relative humidity, and a photoperiod of 14:10 (L:D) h until the emergence of adult parasitoids. T. howardi parasitized and developed in D. saccharalis caterpillars at all the female densities and parasitism periods tested. The emergence and progeny of T. howardi increased with the length of the parasitism period. The shortest life cycle (egg to adult) of T. howardi was 17.00 d at a density of 3:1 and 12 h of parasitism. The parasitism, emergence, and number of T. howardi progeny were highest at a density of 3:1 and at 96 h of parasitism on D. saccharalis third instars.

Development of Eulophidae (Hymenoptera) parasitoids in Diatraea saccharalis (Lepidoptera: Crambidae) pupae exposed to entomopathogenic fungi

“…This suggests that the observed variation was unrelated to treatment and maybe attributed to natural history. This, observation has been reported for these parasitoids in research conducted by Vargas et al (2011), Rodrigues et al (2013), Costa et al (2014aCosta et al ( , 2014b, Glaeser et al (2014), and Pereira et al (2015). These results differ from those found in Aphidius colemani (Viereck) (Hymenoptera: Braconidae), which displayed a decreased development time when its host, Myzus persicae (Sulzer) (Hemiptera: Aphididae), was treated with a suspension of B. bassiana (Emami et al 2013).…”

“…Frequency exceeded 0.82; 0.50 is the minimum value required by quality control processes (Navarro 1998). This high female bias increases the efficiency of parasitism in field releases, because females are responsible for subsequent generations (Rodrigues et al 2013;Costa et al 2014aCosta et al , 2014bBarbosa et al 2015). For example, a low frequency of females has been shown can to compromise the parasitism efficiency of parasitoids (Pereira et al 2009a(Pereira et al , 2009b(Pereira et al , 2010(Pereira et al , 2011.…”

Reproduction of Trichospilus diatraeae (Hymenoptera: Eulophidae) with Different Densities and Parasitism Periods in Anticarsia gemmatalis (Lepidoptera: Noctuidae) Pupae

“…The duration of the life-cycle of Palmistichus elaeisis Delvare & LaSalle, 1993 (Hymenoptera: Eulophidae) decreased with increasing density of females by pupae of A. gemmatalis (PASTORI et al 2012b). In Tetrastichus howardi (Olliff, 1893) (Hymenoptera: Eulophidae), variation of the density of females per pupae of D. saccharalis did not influence the duration of the cycle (days) of the parasitoid (COSTA et al 2014b). The period in which the host is exposed to the parasitoid is also one of the crucial factors for a parasitoid performance check (FÁVERO et al 2013).…”

“…In mass production, the survival capacity of natural enemies is one of the requirements for quality control (QUEIROZ et al 2017). Establishing the best exposure time is essential, as well as the ideal amount of parasitoid/host to guarantee greater longevity of the progeny, because, at high densities and longer contact time there will be less nutritional utilization by high competition, leading to less longevity (COSTA et al 2014b;BARBOSA et al 2016;CHEN et al 2018). In general, female parasitoids tend to present greater longevity in relation to males, since the females have the ability to feed on the host's fluid through the ovipositor.…”

“…Host density, periods of parasitism and host age affect offspring (PEREIRA et al 2010;SILVA et al 2014;BARBOSA et al 2016), sex ratio (CHAI- SAENG et al 2010), parasitism (PEREIRA et al 2010), progeny (COSTA et al 2014aSILVA et al 2015), life cycle duration and longevity of parasitoids (SILVA-TORRES & MATTHEWS 2003;COSTA et al 2014b). Increasing host exposure time should increase parasitoid offspring production, revealing the necessity to study host density and exposure period for parasitoid production (FÁVERO et al 2013).…”