Parasitoid Wasp

Question: How is variation in offspring size (between broods) related to brood size? Hypotheses: Variance in offspring size (between broods) should decrease with increasing brood size as predicted by Charnov and colleagues’ (Charnov and Downhower, 1995; Charnov et al., 1995) small brood invariant. The range in resources put towards reproduction (for mothers producing a certain brood size) should be invariant over brood size (Downhower and Charnov, 1998). We also test assumptions underlying these predictions. Data studied: We use previously collected data on six parasitoid wasp species. Conclusions: As predicted, variance in offspring size among broods decreased with increasing brood size. However, this decrease did not follow closely the quantitative predictions of Charnov and colleagues (Charnov and Downhower, 1995; Charnov et al., 1995). We found some support for the prediction that the range in resources invested in reproduction is invariant over brood size. The assumption that m...

The effect of nine insecticides used in tomato production was evaluated on adults of two Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) populations from Rive and Afonso Cláudio, Espírito Santo State, Brazil. The experiment was developed in an acclimatized chamber at 25 ± 1°C, 70 ± 10% relative humidity and 14 h photophase. Eggs of Anagasta kuehniella (Lepidoptera: Pyralidae), previously immersed in insecticides solutions were offered to females of both T. pretiosum populations. Bacillus thuringiensis, lufenuron and triflumuron had lowest negative effects on parasitism and viability of individuals of these populations; however, abamectin and pyrethroids (betacyflurin 50 and 125 g/l and esfenvalerate) insecticides reduced parasitism rates. T. pretiosum emerged from A. kuehniella eggs treated with esfenvalerate but were not able to parasitize non treated eggs of this host. B. thuringiensis, lufenuron and triflumuron may be used in integrated pest management programs to control tomato pests, because they have moderated negative effect on parasitoid wasps.

Th e species of the two genera of Khoikhoiinae (Hymenoptera, Braconidae) are revised. Th irteen species are recognized, of which five are new and eight were previously described: Khoikhoia anthelionSharkey , sp. n.,K. lissionMason, 1984, K. oligospilosSharkey , sp. n., K. semiadustaMason, 1983, K. solataMason, 1983, K. townesiMason, 1983, K. turneriMason, 1984, Sania browniSharkey , sp. n., S. capensisMason, 1983,

The wasp Ampulex compressa injects venom directly into the prothoracic ganglion of its cockroach host to induce a transient paralysis of the front legs. To identify the biochemical basis for this paralysis, we separated venom components according to molecular size and tested fractions for inhibition of synaptic transmission at the cockroach cercal-giant synapse. Only fractions in the low molecular weight range (<2 kDa) caused synaptic block. Dabsylation of venom components and analysis by HPLC and MALDI-TOF-MS revealed high levels of GABA (25 mM), and its receptor agonists β-alanine (18 mM), and taurine (9 mM) in the active fractions. Each component produces transient block of synaptic transmission at the cercal-giant synapse and block of efferent motor output from the prothoracic ganglion, which mimics effects produced by injection of whole venom. Whole venom evokes picrotoxin-sensitive chloride currents in cockroach central neurons, consistent with a GABAergic action. Together these data demonstrate that Ampulex utilizes GABAergic chloride channel activation as a strategy for central synaptic block to induce transient and focal leg paralysis in its host. © 2006 Wiley Periodicals, Inc. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006

The hymenopterans parasitoids represent the richest group in species within this order. This study aimed to inventory the fauna of hymenopterans parasitoids, in family level, in a fragment of Serra da Babilônia (Southwest of Minas Gerais), through sweep nets, in a period of September 2009 to October 2010. Were collected a totality of 445 specimens of hymenopterans parasitoids, distributed in 20 families, contained in seven superfamilies. In terms of superfamily, 55% were Chalcidoidea (12 families/247 specimens); 23% Ichneumonoidea (two families/104 specimens); 14% Platygastroidea (two families/64 specimens); 3% Proctrotrupoidea (one families/14 specimens); 2% Ceraphronoidea (one families/ seven specimens); 2% Cynipoidea (one families/seven specimens); 1% Chrysidoidea (one families/two specimens). The superfamilies Chalcidoidea
and Ichneumonoidea were the most representative, with a significant numerical supremacy in the first case: twelve families in all. These, two excelled in number of specimens: Eulophidae and Pteromalidae, both containing a large number of described species, with habits and habitats very diversified
and with large variety of host that certainly can explain the large number of specimens collected. About the second case, the highlight was family Braconidae, that the number of representatives found was significantly higher than the second family of the group. The study realized that the sampled
region still is very preserved, mainly in regard to the diversity of hymenopterans parasitoids present. This ensures the maintenance of ecological relationships and the strengthening of chains, and provides the underpinnings for the environmental equilibrium will not come apart.

We report evidence that helps to resolve competing explanations for stability in the classic fig-wasp mutualism. Fig trees are pollinated by wasps that lay their eggs in the tree’s ovules. Each wasp larva then develops at the expense of a fig seed. Upon maturity, the female wasps collect pollen and disperse to a new tree, continuing the cycle. Fig fitness is increased by producing both seeds and wasps, whereas short-term wasp fitness increases only with more wasps, thereby leading to a conflict of interests. We show experimentally that wasps exploit the inner layers of ovules first (biased oviposition), which is consistent with optimal-foraging theory. As oviposition increases, seeds in the middle layer are replaced on a one-to-one basis by pollinator offspring. Finally, in the outer layer of ovules, seeds disappear but are only partially replaced by pollinator offspring, which suggests high wasp mortality, perhaps due to plant defences (biased survival). We propose that selection to increase growth rate in inner ovules trades off against survivorship in outer ovules, and since there are more wasp offspring in inner ovules, biased survival is maintained. Our results suggest that both biased oviposition and biased survivorship ensure seed production in figs, thereby stabilising the mutualism. Finally, we report evidence suggesting that fig trees direct more resources to figs with more seeds, and this may help balance seed and wasp production at the level of the tree. Because an equal allocation would appear to favour the fig’s interests, the fig appears to be in control of the mutualism.

The knowledge of invertebrate diversity in Uruguay is much less as compared to bird and tetrapod fauna, but some important advances have been made within some groups of insects. The Ichneumonidae constitute one of the largest families in the animal kingdom. This family is important because their larvae can be either endo-or ectoparasitoids of larvae or pupae of holometabolous insects as well as Chelicerata. In this study ichneumonid wasps were collected from three environments near the city of Castillos, Rocha Department, Uruguay between December 2014 and December 2016. A total of 5740 Ichneumonidae specimens were collected, representing 19 subfamilies, of which 3685 specimens (64.2%) correspond to three subfamilies: Campopleginae (1533 specimens/26.7%), Ichneumoninae (1303/22.7%) and Cryptinae (849/14.8%) ; all others subfamilies together represented less than 7.0% of the total specimens. In addition, 32 genera were registered for the first time in Uruguay.